diff --git a/.gitignore b/.gitignore
index 2822a599b..8ad48cdeb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,16 @@
 out
+
+# IDEA
 .idea
+*.iml
+local.properties
+
+# Gradle
 .gradle
 build
-local.properties
-*.iml
+
+# Eclipse
+bin
+.settings
+.project
+.classpath
diff --git a/README.md b/README.md
index 594be3332..d09aee3ef 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,8 @@
-[![official JetBrains project](http://jb.gg/badges/official-plastic.svg)](https://confluence.jetbrains.com/display/ALL/JetBrains+on+GitHub)
+[![obsolete JetBrains project](https://jb.gg/badges/obsolete-plastic.svg)](https://confluence.jetbrains.com/display/ALL/JetBrains+on+GitHub)
+
+### This project is obsolete.
+### For the last version of Koans, check [the course](https://www.jetbrains.com/help/education/learner-start-guide.html?section=Kotlin%20Koans) in [the EduTools plugin](https://www.jetbrains.com/help/education/install-edutools-plugin.html?section=IntelliJ%20IDEA) or [online version](https://play.kotlinlang.org/koans/overview).
+### The task content can be found at https://github.com/Kotlin/kotlin-koans-edu.
 
 Kotlin Koans
 ===========
@@ -80,6 +84,6 @@ You can find [here](https://www.jetbrains.com/help/idea/navigating-to-action.htm
 You can solve the similar tasks using Educational Plugin or in the browser:
 
 - EduTools Plugin https://www.jetbrains.com/help/education/learner-start-guide.html?section=Kotlin%20Koans
-- online version of koans http://try.kotl.in
+- online version of koans https://try.kotl.in
 
 The koans tasks for web-demo and educational plugin can be found here: https://github.com/Kotlin/kotlin-koans-edu
diff --git a/build.gradle b/build.gradle
index 5376b74d5..ea0bbf3cc 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1,5 +1,5 @@
 buildscript {
-    ext.kotlin_version = '1.2.10'
+    ext.kotlin_version = '1.3.21'
 
     repositories {
         mavenCentral()
@@ -23,6 +23,10 @@ repositories {
 
 dependencies {
     compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
-    compile 'com.google.guava:guava:16.0'
-    testCompile 'junit:junit:4.12'
+    compile 'com.google.guava:guava:28.0-jre'
+    testCompile 'org.junit.jupiter:junit-jupiter:5.4.0'
 }
+
+test {
+    useJUnitPlatform()
+}
\ No newline at end of file
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 15b8ed9a8..440702935 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.2.1-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.2.1-all.zip
diff --git a/src/i_introduction/_0_Hello_World/n00Start.kt b/src/i_introduction/_0_Hello_World/n00Start.kt
index 352ca5bfc..febe6b0ad 100644
--- a/src/i_introduction/_0_Hello_World/n00Start.kt
+++ b/src/i_introduction/_0_Hello_World/n00Start.kt
@@ -3,6 +3,21 @@ package i_introduction._0_Hello_World
 import util.TODO
 import util.doc0
 
+/*
+
+Note that this project is obsolete.
+For the last version of Koans, check either
+online version
+  - https://play.kotlinlang.org/koans/overview
+or
+the course in the EduTools plugin
+ - https://www.jetbrains.com/help/education/learner-start-guide.html?section=Kotlin%20Koans
+ - https://www.jetbrains.com/help/education/install-edutools-plugin.html?section=IntelliJ%20IDEA
+
+The task content can be found at https://github.com/Kotlin/kotlin-koans-edu.
+
+ */
+
 fun todoTask0(): Nothing = TODO(
     """
         Task 0.
diff --git a/src/i_introduction/_5_String_Templates/n05StringTemplates.kt b/src/i_introduction/_5_String_Templates/n05StringTemplates.kt
index e8bfc187b..7b7f9b625 100644
--- a/src/i_introduction/_5_String_Templates/n05StringTemplates.kt
+++ b/src/i_introduction/_5_String_Templates/n05StringTemplates.kt
@@ -4,15 +4,15 @@ import util.TODO
 import util.doc5
 
 fun example1(a: Any, b: Any) =
-        "This is some text in which variables ($a, $b) appear."
+    "This is some text in which variables ($a, $b) appear."
 
 fun example2(a: Any, b: Any) =
-        "You can write it in a Java way as well. Like this: " + a + ", " + b + "!"
+    "You can write it in a Java way as well. Like this: " + a + ", " + b + "!"
 
 fun example3(c: Boolean, x: Int, y: Int) = "Any expression can be used: ${if (c) x else y}"
 
 fun example4() =
-        """
+    """
 You can use raw strings to write multiline text.
 There is no escaping here, so raw strings are useful for writing regex patterns,
 you don't need to escape a backslash by a backslash.
diff --git a/src/i_introduction/_7_Nullable_Types/n07NullableTypes.kt b/src/i_introduction/_7_Nullable_Types/n07NullableTypes.kt
index 2bb3171b7..1d0109436 100644
--- a/src/i_introduction/_7_Nullable_Types/n07NullableTypes.kt
+++ b/src/i_introduction/_7_Nullable_Types/n07NullableTypes.kt
@@ -23,13 +23,13 @@ fun todoTask7(client: Client?, message: String?, mailer: Mailer): Nothing = TODO
 )
 
 fun sendMessageToClient(
-        client: Client?, message: String?, mailer: Mailer
+    client: Client?, message: String?, mailer: Mailer
 ) {
     todoTask7(client, message, mailer)
 }
 
-class Client (val personalInfo: PersonalInfo?)
-class PersonalInfo (val email: String?)
+class Client(val personalInfo: PersonalInfo?)
+class PersonalInfo(val email: String?)
 
 interface Mailer {
     fun sendMessage(email: String, message: String)
diff --git a/src/i_introduction/_8_Smart_Casts/n08SmartCasts.kt b/src/i_introduction/_8_Smart_Casts/n08SmartCasts.kt
index 16db662f3..6f3a6675e 100644
--- a/src/i_introduction/_8_Smart_Casts/n08SmartCasts.kt
+++ b/src/i_introduction/_8_Smart_Casts/n08SmartCasts.kt
@@ -6,14 +6,15 @@ import util.doc8
 // 'sealed' modifier restricts the type hierarchy:
 // all the subclasses must be declared in the same file
 sealed class Expr
+
 class Num(val value: Int) : Expr()
 class Sum(val left: Expr, val right: Expr) : Expr()
 
 fun eval(e: Expr): Int =
-        when (e) {
-            is Num -> todoTask8(e)
-            is Sum -> todoTask8(e)
-        }
+    when (e) {
+        is Num -> todoTask8(e)
+        is Sum -> todoTask8(e)
+    }
 
 fun todoTask8(expr: Expr): Nothing = TODO(
     """
diff --git a/src/ii_collections/n16FlatMap.kt b/src/ii_collections/n16FlatMap.kt
index 8601e523b..22f9b92f4 100644
--- a/src/ii_collections/n16FlatMap.kt
+++ b/src/ii_collections/n16FlatMap.kt
@@ -7,12 +7,14 @@ fun example() {
     result == listOf('a', 'b', 'c', '1', '2')
 }
 
-val Customer.orderedProducts: Set<Product> get() {
-    // Return all products this customer has ordered
-    todoCollectionTask()
-}
+val Customer.orderedProducts: Set<Product>
+    get() {
+        // Return all products this customer has ordered
+        todoCollectionTask()
+    }
 
-val Shop.allOrderedProducts: Set<Product> get() {
-    // Return all products that were ordered by at least one customer
-    todoCollectionTask()
-}
+val Shop.allOrderedProducts: Set<Product>
+    get() {
+        // Return all products that were ordered by at least one customer
+        todoCollectionTask()
+    }
diff --git a/src/ii_collections/n19Sum.kt b/src/ii_collections/n19Sum.kt
index 5704a29cc..bfd89c56b 100644
--- a/src/ii_collections/n19Sum.kt
+++ b/src/ii_collections/n19Sum.kt
@@ -7,6 +7,6 @@ fun example6() {
 
 fun Customer.getTotalOrderPrice(): Double {
     // Return the sum of prices of all products that a customer has ordered.
-    // Note: a customer may order the same product for several times.
+    // Note: a customer may order the same product several times.
     todoCollectionTask()
 }
diff --git a/src/ii_collections/n22Fold.kt b/src/ii_collections/n22Fold.kt
index ddfc0461c..2fd2f2fcb 100644
--- a/src/ii_collections/n22Fold.kt
+++ b/src/ii_collections/n22Fold.kt
@@ -8,14 +8,13 @@ fun example9() {
 // The same as
 fun whatFoldDoes(): Int {
     var result = 1
-    listOf(1, 2, 3, 4).forEach { element -> result = element * result}
+    listOf(1, 2, 3, 4).forEach { element -> result = element * result }
     return result
 }
 
 fun Shop.getSetOfProductsOrderedByEachCustomer(): Set<Product> {
     // Return the set of products that were ordered by each of the customers
-    return customers.fold(allOrderedProducts, {
-        orderedByAll, customer ->
+    return customers.fold(allOrderedProducts, { orderedByAll, customer ->
         todoCollectionTask()
     })
 }
diff --git a/src/ii_collections/n24ExtensionsOnCollections.kt b/src/ii_collections/n24ExtensionsOnCollections.kt
index 1d7cc64dd..3188c180e 100644
--- a/src/ii_collections/n24ExtensionsOnCollections.kt
+++ b/src/ii_collections/n24ExtensionsOnCollections.kt
@@ -8,7 +8,7 @@ fun todoTask24(): Nothing = TODO(
         The function should do the same as '_24_JavaCode.doSomethingStrangeWithCollection'.
         Replace all invocations of 'todoTask24()' with the appropriate code.
     """,
-        references = { c: Collection<String> -> _24_JavaCode().doSomethingStrangeWithCollection(c) }
+    references = { c: Collection<String> -> _24_JavaCode().doSomethingStrangeWithCollection(c) }
 )
 
 fun doSomethingStrangeWithCollection(collection: Collection<String>): Collection<String>? {
diff --git a/src/ii_collections/todoUtil.kt b/src/ii_collections/todoUtil.kt
index fdeea5754..ce8e75f16 100644
--- a/src/ii_collections/todoUtil.kt
+++ b/src/ii_collections/todoUtil.kt
@@ -3,10 +3,10 @@ package ii_collections
 import util.TODO
 
 fun todoCollectionTask(): Nothing = TODO(
-        """
+    """
            Common task for working with collections.
            Look through the Shop API, which all the tasks are using.
            Each individual task is described in the function name and the comment.
         """,
-        references = { shop: Shop -> shop.customers }
+    references = { shop: Shop -> shop.customers }
 )
diff --git a/src/iii_conventions/MyDateUtil.kt b/src/iii_conventions/MyDateUtil.kt
index 1e97d97ec..dfa7d1f99 100644
--- a/src/iii_conventions/MyDateUtil.kt
+++ b/src/iii_conventions/MyDateUtil.kt
@@ -1,6 +1,6 @@
 package iii_conventions
 
-import iii_conventions.TimeInterval.*
+import iii_conventions.TimeInterval.DAY
 import java.util.*
 
 fun MyDate.nextDay() = addTimeIntervals(DAY, 1)
diff --git a/src/iii_conventions/n28ForLoop.kt b/src/iii_conventions/n28ForLoop.kt
index 520b4297f..1f4369566 100644
--- a/src/iii_conventions/n28ForLoop.kt
+++ b/src/iii_conventions/n28ForLoop.kt
@@ -4,18 +4,22 @@ import util.TODO
 import util.doc28
 
 fun iterateOverCollection(collection: Collection<Int>) {
-    for (element in collection) {}
+    for (element in collection) {
+    }
 }
 
 fun iterateOverString() {
     // You can iterate over anything that has an 'iterator' method, member or extension.
-    for (c in "abcd") {}
+    for (c in "abcd") {
+    }
     "abcd".iterator() //library extension method
 }
 
 fun iterateOverRange() {
-    for (i in 1..10) {}
-    for (c in 'a'..'z') {}
+    for (i in 1..10) {
+    }
+    for (c in 'a'..'z') {
+    }
 }
 
 fun todoTask28(): Nothing = TODO(
diff --git a/src/iii_conventions/n29OperatorsOverloading.kt b/src/iii_conventions/n29OperatorsOverloading.kt
index 5dcd71615..3f96b416f 100644
--- a/src/iii_conventions/n29OperatorsOverloading.kt
+++ b/src/iii_conventions/n29OperatorsOverloading.kt
@@ -1,7 +1,7 @@
 package iii_conventions
 
-import util.TODO
 import iii_conventions.TimeInterval.*
+import util.TODO
 
 fun todoTask29(): Nothing = TODO(
     """
diff --git a/src/iv_properties/n35HowDelegatesWork.kt b/src/iv_properties/n35HowDelegatesWork.kt
index 8f409f971..0462f5556 100644
--- a/src/iv_properties/n35HowDelegatesWork.kt
+++ b/src/iv_properties/n35HowDelegatesWork.kt
@@ -16,7 +16,7 @@ fun todoTask35(): Nothing = TODO(
         Store only the time in milliseconds in 'timeInMillis' property.
         Use the extension functions 'MyDate.toMillis' and 'Long.toDate'.
     """,
-    references = { date: MyDate -> date.toMillis().toDate()}
+    references = { date: MyDate -> date.toMillis().toDate() }
 )
 
 class D {
diff --git a/src/util/kotlinUtil.kt b/src/util/kotlinUtil.kt
index e70e5e60a..3e3704fbf 100644
--- a/src/util/kotlinUtil.kt
+++ b/src/util/kotlinUtil.kt
@@ -2,9 +2,9 @@ package util
 
 @Suppress("UNUSED_PARAMETER")
 fun TODO(
-        task: String,
-        documentation: Unit = Unit,
-        references: Function<Any?> = {}
+    task: String,
+    documentation: Unit = Unit,
+    references: Function<Any?> = {}
 ): Nothing = throw NotImplementedException(task)
 
 class NotImplementedException(message: String) : Exception(message)
\ No newline at end of file
diff --git a/src/v_builders/data.kt b/src/v_builders/data.kt
index becd3dbdb..8e089bd68 100644
--- a/src/v_builders/data.kt
+++ b/src/v_builders/data.kt
@@ -20,4 +20,4 @@ val crocodile = Product("crocodile", 20000.2, 1)
 val cushion = Product("cushion", 131.0, 0)
 
 fun getProducts() = listOf(cactus, cake, camera, car, carrot, cellPhone, chimney, certificate, cigar, coffee, coffeeMaker,
-        cola, cranberry, crocs, crocodile, cushion)
\ No newline at end of file
+    cola, cranberry, crocs, crocodile, cushion)
\ No newline at end of file
diff --git a/src/v_builders/html.kt b/src/v_builders/html.kt
index 7cdd04925..680bef9e4 100644
--- a/src/v_builders/html.kt
+++ b/src/v_builders/html.kt
@@ -14,40 +14,40 @@ open class Tag(val name: String) {
     }
 }
 
-class Attribute(val name : String, val value : String) {
+class Attribute(val name: String, val value: String) {
     override fun toString() = """$name="$value""""
 }
 
-fun <T: Tag> T.set(name: String, value: String?): T {
+fun <T : Tag> T.set(name: String, value: String?): T {
     if (value != null) {
         attributes.add(Attribute(name, value))
     }
     return this
 }
 
-fun <T: Tag> Tag.doInit(tag: T, init: T.() -> Unit): T {
+fun <T : Tag> Tag.doInit(tag: T, init: T.() -> Unit): T {
     tag.init()
     children.add(tag)
     return tag
 }
 
-class Html: Tag("html")
-class Table: Tag("table")
-class Center: Tag("center")
-class TR: Tag("tr")
-class TD: Tag("td")
-class Text(val text: String): Tag("b") {
+class Html : Tag("html")
+class Table : Tag("table")
+class Center : Tag("center")
+class TR : Tag("tr")
+class TD : Tag("td")
+class Text(val text: String) : Tag("b") {
     override fun toString() = text
 }
 
 fun html(init: Html.() -> Unit): Html = Html().apply(init)
 
-fun Html.table(init : Table.() -> Unit) = doInit(Table(), init)
-fun Html.center(init : Center.() -> Unit) = doInit(Center(), init)
+fun Html.table(init: Table.() -> Unit) = doInit(Table(), init)
+fun Html.center(init: Center.() -> Unit) = doInit(Center(), init)
 
-fun Table.tr(color: String? = null, init : TR.() -> Unit) = doInit(TR(), init).set("bgcolor", color)
+fun Table.tr(color: String? = null, init: TR.() -> Unit) = doInit(TR(), init).set("bgcolor", color)
 
-fun TR.td(color: String? = null, align : String = "left", init : TD.() -> Unit) = doInit(TD(), init).set("align", align).set("bgcolor", color)
+fun TR.td(color: String? = null, align: String = "left", init: TD.() -> Unit) = doInit(TD(), init).set("align", align).set("bgcolor", color)
 
-fun Tag.text(s : Any?) = doInit(Text(s.toString()), {})
+fun Tag.text(s: Any?) = doInit(Text(s.toString()), {})
 
diff --git a/src/v_builders/htmlDemo.kt b/src/v_builders/htmlDemo.kt
index e45ab7d18..59ba4feb7 100644
--- a/src/v_builders/htmlDemo.kt
+++ b/src/v_builders/htmlDemo.kt
@@ -8,7 +8,7 @@ import javax.swing.SwingConstants.CENTER
 
 
 fun main(args: Array<String>) {
-    with (JFrame("Product popularity")) {
+    with(JFrame("Product popularity")) {
         setSize(600, 600)
         defaultCloseOperation = JFrame.EXIT_ON_CLOSE
         add(JScrollPane(JLabel(renderProductTable(), CENTER)))
diff --git a/src/v_builders/n37StringAndMapBuilders.kt b/src/v_builders/n37StringAndMapBuilders.kt
index acf976b2c..76e554f5a 100644
--- a/src/v_builders/n37StringAndMapBuilders.kt
+++ b/src/v_builders/n37StringAndMapBuilders.kt
@@ -1,7 +1,6 @@
 package v_builders
 
 import util.TODO
-import java.util.*
 
 fun buildStringExample(): String {
     fun buildString(build: StringBuilder.() -> Unit): String {
diff --git a/src/v_builders/n39HtmlBuilders.kt b/src/v_builders/n39HtmlBuilders.kt
index 8a50a6e19..578d50521 100644
--- a/src/v_builders/n39HtmlBuilders.kt
+++ b/src/v_builders/n39HtmlBuilders.kt
@@ -6,7 +6,7 @@ import v_builders.data.getProducts
 import v_builders.htmlLibrary.*
 
 fun getTitleColor() = "#b9c9fe"
-fun getCellColor(row: Int, column: Int) = if ((row + column) %2 == 0) "#dce4ff" else "#eff2ff"
+fun getCellColor(row: Int, column: Int) = if ((row + column) % 2 == 0) "#dce4ff" else "#eff2ff"
 
 fun todoTask39(): Nothing = TODO(
     """
diff --git a/src/v_builders/n40BuildersHowItWorks.kt b/src/v_builders/n40BuildersHowItWorks.kt
index ca7e53930..95a8a705e 100644
--- a/src/v_builders/n40BuildersHowItWorks.kt
+++ b/src/v_builders/n40BuildersHowItWorks.kt
@@ -32,7 +32,7 @@ fun task40() = linkedMapOf<Int, Answer>(
     b. function declaration
     c. function invocation
  */
-        1 to insertAnswerHere(),
+    1 to insertAnswerHere(),
 
 /*
 2. In the Kotlin code
@@ -49,7 +49,7 @@ fun task40() = linkedMapOf<Int, Answer>(
   b. argument name
   c. argument value
  */
-        2 to insertAnswerHere(),
+    2 to insertAnswerHere(),
 
 /*
 3. The block
@@ -62,7 +62,7 @@ from the previous question is:
   c. something mysterious
 
  */
-        3 to insertAnswerHere(),
+    3 to insertAnswerHere(),
 
 /*
 4. For the code
@@ -84,5 +84,5 @@ which of the following is true:
                   }
             }
  */
-        4 to insertAnswerHere()
+    4 to insertAnswerHere()
 )
diff --git a/src/vi_generics/n41GenericFunctions.kt b/src/vi_generics/n41GenericFunctions.kt
index 4a58b02aa..38d333c9c 100644
--- a/src/vi_generics/n41GenericFunctions.kt
+++ b/src/vi_generics/n41GenericFunctions.kt
@@ -13,10 +13,10 @@ fun task41(): Nothing = TODO(
         You should write a function that splits the collection into two collections given as arguments.
         The signature of the 'toCollection()' function from the standard library may help you.
     """,
-        references = { l: List<Int> ->
-            l.partition { it > 0 }
-            l.toCollection(HashSet<Int>())
-        }
+    references = { l: List<Int> ->
+        l.partition { it > 0 }
+        l.toCollection(HashSet<Int>())
+    }
 )
 
 fun List<String>.partitionWordsAndLines(): Pair<List<String>, List<String>> {
diff --git a/test/i_introduction/_0_Hello_World/N00StartKtTest.kt b/test/i_introduction/_0_Hello_World/N00StartKtTest.kt
index fba012b64..c54f2945e 100644
--- a/test/i_introduction/_0_Hello_World/N00StartKtTest.kt
+++ b/test/i_introduction/_0_Hello_World/N00StartKtTest.kt
@@ -1,10 +1,11 @@
 package i_introduction._0_Hello_World
 
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N00StartKtTest {
-    @Test fun testOk() {
+    @Test
+    fun testOk() {
         assertEquals("OK", task0())
     }
 }
\ No newline at end of file
diff --git a/test/i_introduction/_10_Object_Expressions/N10ObjectExpressionsKtTest.kt b/test/i_introduction/_10_Object_Expressions/N10ObjectExpressionsKtTest.kt
index e4109778c..0e1924707 100644
--- a/test/i_introduction/_10_Object_Expressions/N10ObjectExpressionsKtTest.kt
+++ b/test/i_introduction/_10_Object_Expressions/N10ObjectExpressionsKtTest.kt
@@ -1,10 +1,11 @@
 package i_introduction._10_Object_Expressions
 
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N10ObjectExpressionsKtTest {
-    @Test fun testSort() {
+    @Test
+    fun testSort() {
         assertEquals(listOf(5, 2, 1), task10())
     }
 }
diff --git a/test/i_introduction/_11_SAM_Conversions/N11SAMConversionsKtTest.kt b/test/i_introduction/_11_SAM_Conversions/N11SAMConversionsKtTest.kt
index e8ea97fce..f07bf41d3 100644
--- a/test/i_introduction/_11_SAM_Conversions/N11SAMConversionsKtTest.kt
+++ b/test/i_introduction/_11_SAM_Conversions/N11SAMConversionsKtTest.kt
@@ -1,10 +1,11 @@
 package i_introduction._11_SAM_Conversions
 
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N11SAMConversionsKtTest {
-    @Test fun testSort() {
+    @Test
+    fun testSort() {
         assertEquals(listOf(5, 2, 1), task11())
     }
 }
diff --git a/test/i_introduction/_12_Extensions_On_Collections/N12ExtensionsOnCollectionsKtTest.kt b/test/i_introduction/_12_Extensions_On_Collections/N12ExtensionsOnCollectionsKtTest.kt
index 3c15f1764..801a0c0ba 100644
--- a/test/i_introduction/_12_Extensions_On_Collections/N12ExtensionsOnCollectionsKtTest.kt
+++ b/test/i_introduction/_12_Extensions_On_Collections/N12ExtensionsOnCollectionsKtTest.kt
@@ -1,10 +1,11 @@
 package i_introduction._12_Extensions_On_Collections
 
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N12ExtensionsOnCollectionsKtTest {
-    @Test fun testSort() {
+    @Test
+    fun testSort() {
         assertEquals(listOf(5, 2, 1), task12())
     }
 }
diff --git a/test/i_introduction/_1_Java_To_Kotlin_Converter/N01JavaToKotlinConverterKtTest.kt b/test/i_introduction/_1_Java_To_Kotlin_Converter/N01JavaToKotlinConverterKtTest.kt
index 8ec1046bf..c6a27b920 100644
--- a/test/i_introduction/_1_Java_To_Kotlin_Converter/N01JavaToKotlinConverterKtTest.kt
+++ b/test/i_introduction/_1_Java_To_Kotlin_Converter/N01JavaToKotlinConverterKtTest.kt
@@ -1,10 +1,11 @@
 package i_introduction._1_Java_To_Kotlin_Converter
 
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N01JavaToKotlinConverterKtTest {
-    @Test fun collection() {
+    @Test
+    fun collection() {
         assertEquals("{1, 2, 3, 42, 555}", task1(listOf(1, 2, 3, 42, 555)))
     }
 }
diff --git a/test/i_introduction/_2_Named_Arguments/N02NamedArgumentsKtTest.kt b/test/i_introduction/_2_Named_Arguments/N02NamedArgumentsKtTest.kt
index 4fe3a86c7..0463722d5 100644
--- a/test/i_introduction/_2_Named_Arguments/N02NamedArgumentsKtTest.kt
+++ b/test/i_introduction/_2_Named_Arguments/N02NamedArgumentsKtTest.kt
@@ -1,10 +1,12 @@
 package i_introduction._2_Named_Arguments
 
-import org.junit.Assert.assertEquals
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N02NamedArgumentsKtTest {
 
-    @org.junit.Test fun testJoinToString() {
+    @Test
+    fun testJoinToString() {
         assertEquals("{1, 2, 3, 42, 555}", task2(listOf(1, 2, 3, 42, 555)))
     }
 
diff --git a/test/i_introduction/_3_Default_Arguments/N03DefaultArgumentsKtTest.kt b/test/i_introduction/_3_Default_Arguments/N03DefaultArgumentsKtTest.kt
index 5e2c142e4..1a23ff522 100644
--- a/test/i_introduction/_3_Default_Arguments/N03DefaultArgumentsKtTest.kt
+++ b/test/i_introduction/_3_Default_Arguments/N03DefaultArgumentsKtTest.kt
@@ -1,11 +1,12 @@
 package i_introduction._3_Default_Arguments
 
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N03DefaultArgumentsKtTest {
 
-    @Test fun testDefaultAndNamedParams() {
+    @Test
+    fun testDefaultAndNamedParams() {
         assertEquals("a42b1C42D2", task3())
     }
 }
\ No newline at end of file
diff --git a/test/i_introduction/_4_Lambdas/N04LambdasKtTest.kt b/test/i_introduction/_4_Lambdas/N04LambdasKtTest.kt
index 341cf671b..ae198252e 100644
--- a/test/i_introduction/_4_Lambdas/N04LambdasKtTest.kt
+++ b/test/i_introduction/_4_Lambdas/N04LambdasKtTest.kt
@@ -1,15 +1,17 @@
 package i_introduction._4_Lambdas
 
-import org.junit.Assert.assertFalse
-import org.junit.Assert.assertTrue
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertFalse
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.Test
 
 class N04LambdasKtTest {
-    @Test fun contains() {
+    @Test
+    fun contains() {
         assertTrue(task4(listOf(1, 2, 3)))
     }
 
-    @Test fun notContains() {
+    @Test
+    fun notContains() {
         assertFalse(task4(listOf(1, 3, 5)))
     }
 }
\ No newline at end of file
diff --git a/test/i_introduction/_5_String_Templates/N05StringTemplatesKtTest.kt b/test/i_introduction/_5_String_Templates/N05StringTemplatesKtTest.kt
index 98466b32e..80f4099a5 100644
--- a/test/i_introduction/_5_String_Templates/N05StringTemplatesKtTest.kt
+++ b/test/i_introduction/_5_String_Templates/N05StringTemplatesKtTest.kt
@@ -1,20 +1,22 @@
 package i_introduction._5_String_Templates
 
-import org.junit.Assert.assertFalse
-import org.junit.Assert.assertTrue
-import org.junit.Test
-import java.util.regex.Pattern
+import org.junit.jupiter.api.Assertions.assertFalse
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.Test
 
 class N05StringTemplatesKtTest {
-    @Test fun match() {
+    @Test
+    fun match() {
         assertTrue("11 MAR 1952".matches(task5().toRegex()))
     }
 
-    @Test fun match1() {
+    @Test
+    fun match1() {
         assertTrue("24 AUG 1957".matches(task5().toRegex()))
     }
 
-    @Test fun doNotMatch() {
+    @Test
+    fun doNotMatch() {
         assertFalse("24 RRR 1957".matches(task5().toRegex()))
     }
 }
diff --git a/test/i_introduction/_6_Data_Classes/N06DataClassesKtTest.kt b/test/i_introduction/_6_Data_Classes/N06DataClassesKtTest.kt
index 17e1e11a6..942bdfdfb 100644
--- a/test/i_introduction/_6_Data_Classes/N06DataClassesKtTest.kt
+++ b/test/i_introduction/_6_Data_Classes/N06DataClassesKtTest.kt
@@ -1,11 +1,12 @@
 package i_introduction._6_Data_Classes
 
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 
 class N06DataClassesKtTest {
-    @Test fun testListOfPeople() {
+    @Test
+    fun testListOfPeople() {
         assertEquals("[Person(name=Alice, age=29), Person(name=Bob, age=31)]", task6().toString())
     }
 }
\ No newline at end of file
diff --git a/test/i_introduction/_7_Nullable_Types/N07NullableTypesKtTest.kt b/test/i_introduction/_7_Nullable_Types/N07NullableTypesKtTest.kt
index 5f10d1b47..c0b3967d3 100644
--- a/test/i_introduction/_7_Nullable_Types/N07NullableTypesKtTest.kt
+++ b/test/i_introduction/_7_Nullable_Types/N07NullableTypesKtTest.kt
@@ -1,49 +1,52 @@
 package i_introduction._7_Nullable_Types
 
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N07NullableTypesKtTest {
-    fun testSendMessageToClient(
-            client: Client?,
-            message: String?,
-            email: String? = null,
-            shouldBeInvoked: Boolean = false
+    private fun testSendMessageToClient(
+        client: Client?,
+        message: String?,
+        email: String? = null,
+        shouldBeInvoked: Boolean = false
     ) {
         var invoked = false
         sendMessageToClient(client, message, object : Mailer {
             override fun sendMessage(actualEmail: String, actualMessage: String) {
                 invoked = true
-                assertEquals("The message is not as expected:",
-                        message, actualMessage)
-                assertEquals("The email is not as expected:",
-                        email, actualEmail)
+                assertEquals(message, actualMessage, "The message is not as expected:")
+                assertEquals(email, actualEmail, "The email is not as expected:")
             }
         })
-        assertEquals("The function 'sendMessage' should${if (shouldBeInvoked) "" else "n't"} be invoked",
-                shouldBeInvoked, invoked)
+        assertEquals(shouldBeInvoked, invoked,
+            "The function 'sendMessage' should${if (shouldBeInvoked) "" else "n't"} be invoked")
     }
 
-    @Test fun everythingIsOk() {
+    @Test
+    fun everythingIsOk() {
         testSendMessageToClient(Client(PersonalInfo("bob@gmail.com")),
-                "Hi Bob! We have an awesome proposition for you...",
-                "bob@gmail.com",
-                true)
+            "Hi Bob! We have an awesome proposition for you...",
+            "bob@gmail.com",
+            true)
     }
 
-    @Test fun noMessage() {
+    @Test
+    fun noMessage() {
         testSendMessageToClient(Client(PersonalInfo("bob@gmail.com")), null)
     }
 
-    @Test fun noEmail() {
+    @Test
+    fun noEmail() {
         testSendMessageToClient(Client(PersonalInfo(null)), "Hi Bob! We have an awesome proposition for you...")
     }
 
-    @Test fun noPersonalInfo() {
+    @Test
+    fun noPersonalInfo() {
         testSendMessageToClient(Client(null), "Hi Bob! We have an awesome proposition for you...")
     }
 
-    @Test fun noClient() {
+    @Test
+    fun noClient() {
         testSendMessageToClient(null, "Hi Bob! We have an awesome proposition for you...")
     }
 }
\ No newline at end of file
diff --git a/test/i_introduction/_8_Smart_Casts/N08SmartCastsKtTest.kt b/test/i_introduction/_8_Smart_Casts/N08SmartCastsKtTest.kt
index 59bb54fdc..53ca9f368 100644
--- a/test/i_introduction/_8_Smart_Casts/N08SmartCastsKtTest.kt
+++ b/test/i_introduction/_8_Smart_Casts/N08SmartCastsKtTest.kt
@@ -1,18 +1,21 @@
 package i_introduction._8_Smart_Casts
 
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N08SmartCastsKtTest {
-    @Test fun testNum() {
-        assertEquals("'eval' on Num should work:", 2, eval(Num(2)))
+    @Test
+    fun testNum() {
+        assertEquals(2, eval(Num(2)), "'eval' on Num should work:")
     }
 
-    @Test fun testSum() {
-        assertEquals("'eval' on Sum should work:", 3, eval(Sum(Num(2), Num(1))))
+    @Test
+    fun testSum() {
+        assertEquals(3, eval(Sum(Num(2), Num(1))), "'eval' on Sum should work:")
     }
 
-    @Test fun testRecursion() {
-        assertEquals("'eval' should work recursively:", 6, eval(Sum(Sum(Num(1), Num(2)), Num(3))))
+    @Test
+    fun testRecursion() {
+        assertEquals(6, eval(Sum(Sum(Num(1), Num(2)), Num(3))), "'eval' should work recursively:")
     }
 }
\ No newline at end of file
diff --git a/test/i_introduction/_9_Extension_Functions/N09ExtensionFunctionsKtTest.kt b/test/i_introduction/_9_Extension_Functions/N09ExtensionFunctionsKtTest.kt
index 2f9a93ca5..cd27b1b44 100644
--- a/test/i_introduction/_9_Extension_Functions/N09ExtensionFunctionsKtTest.kt
+++ b/test/i_introduction/_9_Extension_Functions/N09ExtensionFunctionsKtTest.kt
@@ -1,14 +1,16 @@
 package i_introduction._9_Extension_Functions
 
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N09ExtensionFunctionsKtTest {
-    @Test fun testIntExtension() {
-        assertEquals("Rational number creation error: ", RationalNumber(4, 1), 4.r())
+    @Test
+    fun testIntExtension() {
+        assertEquals(RationalNumber(4, 1), 4.r(), "Rational number creation error: ")
     }
 
-    @Test fun testPairExtension() {
-        assertEquals("Rational number creation error: ", RationalNumber(2, 3), Pair(2, 3).r())
+    @Test
+    fun testPairExtension() {
+        assertEquals(RationalNumber(2, 3), Pair(2, 3).r(), "Rational number creation error: ")
     }
 }
\ No newline at end of file
diff --git a/test/ii_collections/N13IntroductionKtTest.kt b/test/ii_collections/N13IntroductionKtTest.kt
index f2afddde8..4aa961c15 100644
--- a/test/ii_collections/N13IntroductionKtTest.kt
+++ b/test/ii_collections/N13IntroductionKtTest.kt
@@ -2,11 +2,12 @@ package ii_collections
 
 import ii_collections.data.customers
 import ii_collections.data.shop
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N13IntroductionKtTest {
-    @Test fun testSetOfCustomers() {
+    @Test
+    fun testSetOfCustomers() {
         assertEquals(customers.values.toSet(), shop.getSetOfCustomers())
     }
 }
diff --git a/test/ii_collections/N14FilterMapKtTest.kt b/test/ii_collections/N14FilterMapKtTest.kt
index 7d1ef617b..85aa5f7b1 100644
--- a/test/ii_collections/N14FilterMapKtTest.kt
+++ b/test/ii_collections/N14FilterMapKtTest.kt
@@ -1,18 +1,20 @@
 package ii_collections
 
 import ii_collections.data.*
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N14FilterMapKtTest {
-    @Test fun testCitiesCustomersAreFrom() {
+    @Test
+    fun testCitiesCustomersAreFrom() {
         assertEquals(setOf(Canberra, Vancouver, Budapest, Ankara, Tokyo), shop.getCitiesCustomersAreFrom())
     }
 
     /**
      * Returns the list of the customers who live in the city 'city'
      */
-    @Test fun testCustomersFromCity() {
+    @Test
+    fun testCustomersFromCity() {
         assertEquals(listOf(customers[lucas], customers[cooper]), shop.getCustomersFrom(Canberra))
     }
 }
diff --git a/test/ii_collections/N15AllAnyAndOtherPredicatesKtTest.kt b/test/ii_collections/N15AllAnyAndOtherPredicatesKtTest.kt
index 66762b54c..cf11b0458 100644
--- a/test/ii_collections/N15AllAnyAndOtherPredicatesKtTest.kt
+++ b/test/ii_collections/N15AllAnyAndOtherPredicatesKtTest.kt
@@ -1,28 +1,33 @@
 package ii_collections
 
 import ii_collections.data.*
-import org.junit.Assert.*
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.*
+import org.junit.jupiter.api.Test
 
 class N15AllAnyAndOtherPredicatesKtTest {
-    @Test fun testCustomerIsFromCity() {
+    @Test
+    fun testCustomerIsFromCity() {
         assertTrue(customers[lucas]!!.isFrom(Canberra))
         assertFalse(customers[lucas]!!.isFrom(Budapest))
     }
 
-    @Test fun testAllCustomersAreFromCity() {
+    @Test
+    fun testAllCustomersAreFromCity() {
         assertFalse(shop.checkAllCustomersAreFrom(Canberra))
     }
 
-    @Test fun testAnyCustomerIsFromCity() {
+    @Test
+    fun testAnyCustomerIsFromCity() {
         assertTrue(shop.hasCustomerFrom(Canberra))
     }
 
-    @Test fun testCountCustomersFromCity() {
+    @Test
+    fun testCountCustomersFromCity() {
         assertEquals(2, shop.countCustomersFrom(Canberra))
     }
 
-    @Test fun testFirstCustomerFromCity() {
+    @Test
+    fun testFirstCustomerFromCity() {
         assertEquals(customers[lucas], shop.findFirstCustomerFrom(Canberra))
         assertEquals(null, shop.findFirstCustomerFrom(City("Chicago")))
     }
diff --git a/test/ii_collections/N16FlatMapKtTest.kt b/test/ii_collections/N16FlatMapKtTest.kt
index 6e30e2e9c..8a4b5b627 100644
--- a/test/ii_collections/N16FlatMapKtTest.kt
+++ b/test/ii_collections/N16FlatMapKtTest.kt
@@ -1,15 +1,17 @@
 package ii_collections
 
 import ii_collections.data.*
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N16FlatMapKtTest {
-    @Test fun testGetOrderedProductsSet() {
+    @Test
+    fun testGetOrderedProductsSet() {
         assertEquals(setOf(idea), customers[reka]!!.orderedProducts)
     }
 
-    @Test fun testGetAllOrderedProducts() {
+    @Test
+    fun testGetAllOrderedProducts() {
         assertEquals(orderedProducts, shop.allOrderedProducts)
     }
 }
diff --git a/test/ii_collections/N17MaxMinKtTest.kt b/test/ii_collections/N17MaxMinKtTest.kt
index f4b92f9a7..25ddecfdf 100644
--- a/test/ii_collections/N17MaxMinKtTest.kt
+++ b/test/ii_collections/N17MaxMinKtTest.kt
@@ -1,15 +1,17 @@
 package ii_collections
 
 import ii_collections.data.*
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N17MaxMinKtTest {
-    @Test fun testCustomerWithMaximumNumberOfOrders() {
+    @Test
+    fun testCustomerWithMaximumNumberOfOrders() {
         assertEquals(customers[reka], shop.getCustomerWithMaximumNumberOfOrders())
     }
 
-    @Test fun testTheMostExpensiveOrderedProduct() {
+    @Test
+    fun testTheMostExpensiveOrderedProduct() {
         assertEquals(rubyMine, customers[nathan]!!.getMostExpensiveOrderedProduct())
     }
 }
diff --git a/test/ii_collections/N18SortKtTest.kt b/test/ii_collections/N18SortKtTest.kt
index 1cb9ecb25..8bdb04f14 100644
--- a/test/ii_collections/N18SortKtTest.kt
+++ b/test/ii_collections/N18SortKtTest.kt
@@ -2,11 +2,12 @@ package ii_collections
 
 import ii_collections.data.shop
 import ii_collections.data.sortedCustomers
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N18SortKtTest {
-    @Test fun testGetCustomersSortedByNumberOfOrders() {
+    @Test
+    fun testGetCustomersSortedByNumberOfOrders() {
         assertEquals(sortedCustomers, shop.getCustomersSortedByNumberOfOrders())
     }
 }
diff --git a/test/ii_collections/N19SumKtTest.kt b/test/ii_collections/N19SumKtTest.kt
index 50d25ed0d..5f7882f5b 100644
--- a/test/ii_collections/N19SumKtTest.kt
+++ b/test/ii_collections/N19SumKtTest.kt
@@ -3,15 +3,17 @@ package ii_collections
 import ii_collections.data.customers
 import ii_collections.data.lucas
 import ii_collections.data.nathan
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N19SumKtTest {
-    @Test fun testGetTotalOrderPrice() {
+    @Test
+    fun testGetTotalOrderPrice() {
         assertEquals(148.0, customers[nathan]!!.getTotalOrderPrice(), 0.001)
     }
 
-    @Test fun testTotalPriceForRepeatedProducts() {
+    @Test
+    fun testTotalPriceForRepeatedProducts() {
         assertEquals(586.0, customers[lucas]!!.getTotalOrderPrice(), 0.001)
     }
 }
diff --git a/test/ii_collections/N20GroupByKtTest.kt b/test/ii_collections/N20GroupByKtTest.kt
index dca8e6a53..a8b2e543c 100644
--- a/test/ii_collections/N20GroupByKtTest.kt
+++ b/test/ii_collections/N20GroupByKtTest.kt
@@ -2,11 +2,12 @@ package ii_collections
 
 import ii_collections.data.groupedByCities
 import ii_collections.data.shop
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N20GroupByKtTest {
-    @Test fun testGroupCustomersByCity() {
+    @Test
+    fun testGroupCustomersByCity() {
         assertEquals(groupedByCities, shop.groupCustomersByCity())
     }
 }
diff --git a/test/ii_collections/N21PartitionKtTest.kt b/test/ii_collections/N21PartitionKtTest.kt
index 256050fc2..0a9347549 100644
--- a/test/ii_collections/N21PartitionKtTest.kt
+++ b/test/ii_collections/N21PartitionKtTest.kt
@@ -3,11 +3,12 @@ package ii_collections
 import ii_collections.data.customers
 import ii_collections.data.reka
 import ii_collections.data.shop
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N21PartitionKtTest {
-    @Test fun testGetCustomersWhoHaveMoreUndeliveredOrdersThanDelivered() {
+    @Test
+    fun testGetCustomersWhoHaveMoreUndeliveredOrdersThanDelivered() {
         assertEquals(setOf(customers[reka]), shop.getCustomersWithMoreUndeliveredOrdersThanDelivered())
     }
 }
diff --git a/test/ii_collections/N22FoldKtTest.kt b/test/ii_collections/N22FoldKtTest.kt
index 5b182a80e..1b0494761 100644
--- a/test/ii_collections/N22FoldKtTest.kt
+++ b/test/ii_collections/N22FoldKtTest.kt
@@ -1,21 +1,22 @@
 package ii_collections
 
 import ii_collections.data.*
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 
 class N22FoldKtTest {
-    @Test fun testGetProductsOrderedByAllCustomers() {
+    @Test
+    fun testGetProductsOrderedByAllCustomers() {
         val testShop = shop("test shop for 'fold'",
-                customer(lucas, Canberra,
-                        order(idea),
-                        order(webStorm)
-                ),
-                customer(reka, Budapest,
-                        order(idea),
-                        order(youTrack)
-                )
+            customer(lucas, Canberra,
+                order(idea),
+                order(webStorm)
+            ),
+            customer(reka, Budapest,
+                order(idea),
+                order(youTrack)
+            )
         )
         assertEquals(setOf(idea), testShop.getSetOfProductsOrderedByEachCustomer())
     }
diff --git a/test/ii_collections/N23CompoundTasksKtTest.kt b/test/ii_collections/N23CompoundTasksKtTest.kt
index b2f341161..f0c0df107 100644
--- a/test/ii_collections/N23CompoundTasksKtTest.kt
+++ b/test/ii_collections/N23CompoundTasksKtTest.kt
@@ -1,35 +1,38 @@
 package ii_collections
 
 import ii_collections.data.*
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N23CompoundTasksKtTest {
-    @Test fun testGetCustomersWhoOrderedProduct() {
+    @Test
+    fun testGetCustomersWhoOrderedProduct() {
         assertEquals(setOf(customers[reka], customers[asuka]), shop.getCustomersWhoOrderedProduct(idea))
     }
 
-    @Test fun testMostExpensiveDeliveredProduct() {
+    @Test
+    fun testMostExpensiveDeliveredProduct() {
         val testShop = shop("test shop for 'most expensive delivered product'",
-                customer(lucas, Canberra,
-                        order(idea, isDelivered = false),
-                        order(reSharper)
-                )
+            customer(lucas, Canberra,
+                order(idea, isDelivered = false),
+                order(reSharper)
+            )
         )
         assertEquals(reSharper, testShop.customers[0].getMostExpensiveDeliveredProduct())
     }
 
-    @Test fun testNumberOfTimesEachProductWasOrdered() {
+    @Test
+    fun testNumberOfTimesEachProductWasOrdered() {
         assertEquals(4, shop.getNumberOfTimesProductWasOrdered(idea))
     }
 
-    @Test fun testNumberOfTimesEachProductWasOrderedForRepeatedProduct() {
-        assertEquals("A customer may order a product for several times",
-                3, shop.getNumberOfTimesProductWasOrdered(reSharper))
+    @Test
+    fun testNumberOfTimesEachProductWasOrderedForRepeatedProduct() {
+        assertEquals(3, shop.getNumberOfTimesProductWasOrdered(reSharper), "A customer may order a product for several times")
     }
 
-    @Test fun testNumberOfTimesEachProductWasOrderedForRepeatedInOrderProduct() {
-        assertEquals("An order may contain a particular product more than once",
-                3, shop.getNumberOfTimesProductWasOrdered(phpStorm))
+    @Test
+    fun testNumberOfTimesEachProductWasOrderedForRepeatedInOrderProduct() {
+        assertEquals(3, shop.getNumberOfTimesProductWasOrdered(phpStorm), "An order may contain a particular product more than once")
     }
 }
diff --git a/test/ii_collections/N24ExtensionsOnCollectionsKtTest.kt b/test/ii_collections/N24ExtensionsOnCollectionsKtTest.kt
index 1b363a9cc..e3fd8862f 100644
--- a/test/ii_collections/N24ExtensionsOnCollectionsKtTest.kt
+++ b/test/ii_collections/N24ExtensionsOnCollectionsKtTest.kt
@@ -1,31 +1,35 @@
 package ii_collections
 
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N24ExtensionsOnCollectionsKtTest {
-    @Test fun testCollectionOfOneElement() {
+    @Test
+    fun testCollectionOfOneElement() {
         doTest(listOf("a"), listOf("a"))
     }
 
-    @Test fun testEmptyCollection() {
+    @Test
+    fun testEmptyCollection() {
         doTest(null, listOf())
     }
 
-    @Test fun testSimpleCollection() {
+    @Test
+    fun testSimpleCollection() {
         doTest(listOf("a", "c"), listOf("a", "bb", "c"))
     }
 
-    @Test fun testCollectionWithEmptyStrings() {
+    @Test
+    fun testCollectionWithEmptyStrings() {
         doTest(listOf("", "", "", ""), listOf("", "", "", "", "a", "bb", "ccc", "dddd"))
     }
 
-    @Test fun testCollectionWithTwoGroupsOfMaximalSize() {
+    @Test
+    fun testCollectionWithTwoGroupsOfMaximalSize() {
         doTest(listOf("a", "c"), listOf("a", "bb", "c", "dd"))
     }
 
     private fun doTest(expected: Collection<String>?, argument: Collection<String>) {
-        assertEquals("The function 'doSomethingStrangeWithCollection' should do at least something with a collection:",
-                expected, doSomethingStrangeWithCollection(argument))
+        assertEquals(expected, doSomethingStrangeWithCollection(argument), "The function 'doSomethingStrangeWithCollection' should do at least something with a collection:")
     }
 }
\ No newline at end of file
diff --git a/test/ii_collections/TestShop.kt b/test/ii_collections/TestShop.kt
index e7abbe849..c706716b1 100644
--- a/test/ii_collections/TestShop.kt
+++ b/test/ii_collections/TestShop.kt
@@ -37,34 +37,33 @@ fun order(vararg products: Product, isDelivered: Boolean = true) = Order(product
 fun shop(name: String, vararg customers: Customer) = Shop(name, customers.toList())
 
 val shop = shop("jb test shop",
-        customer(lucas, Canberra,
-                order(reSharper),
-                order(reSharper, dotMemory, dotTrace)
-        ),
-        customer(cooper, Canberra),
-        customer(nathan, Vancouver,
-                order(rubyMine, webStorm)
-        ),
-        customer(reka, Budapest,
-                order(idea, isDelivered = false),
-                order(idea, isDelivered = false),
-                order(idea)
-        ),
-        customer(bajram, Ankara,
-                order(reSharper)
-        ),
-        customer(asuka, Tokyo,
-                order(idea)
-        ),
-        customer(riku, Tokyo,
-                order(phpStorm, phpStorm),
-                order(phpStorm)
-        )
+    customer(lucas, Canberra,
+        order(reSharper),
+        order(reSharper, dotMemory, dotTrace)
+    ),
+    customer(cooper, Canberra),
+    customer(nathan, Vancouver,
+        order(rubyMine, webStorm)
+    ),
+    customer(reka, Budapest,
+        order(idea, isDelivered = false),
+        order(idea, isDelivered = false),
+        order(idea)
+    ),
+    customer(bajram, Ankara,
+        order(reSharper)
+    ),
+    customer(asuka, Tokyo,
+        order(idea)
+    ),
+    customer(riku, Tokyo,
+        order(phpStorm, phpStorm),
+        order(phpStorm)
+    )
 
 )
 
-val customers: Map<String, Customer> = shop.customers.fold(hashMapOf(), {
-    map, customer ->
+val customers: Map<String, Customer> = shop.customers.fold(hashMapOf(), { map, customer ->
     map[customer.name] = customer
     map
 })
@@ -74,9 +73,9 @@ val orderedProducts = setOf(idea, reSharper, dotTrace, dotMemory, rubyMine, webS
 val sortedCustomers = listOf(cooper, nathan, bajram, asuka, lucas, riku, reka).map { customers[it] }
 
 val groupedByCities = mapOf(
-        Canberra to listOf(lucas, cooper),
-        Vancouver to listOf(nathan),
-        Budapest to listOf(reka),
-        Ankara to listOf(bajram),
-        Tokyo to listOf(asuka, riku)
+    Canberra to listOf(lucas, cooper),
+    Vancouver to listOf(nathan),
+    Budapest to listOf(reka),
+    Ankara to listOf(bajram),
+    Tokyo to listOf(asuka, riku)
 ).mapValues { it.value.map { name -> customers[name] } }
diff --git a/test/iii_conventions/N25ComparisonKtTest.kt b/test/iii_conventions/N25ComparisonKtTest.kt
index 4031bc681..61a4870bd 100644
--- a/test/iii_conventions/N25ComparisonKtTest.kt
+++ b/test/iii_conventions/N25ComparisonKtTest.kt
@@ -1,25 +1,28 @@
 package iii_conventions
 
 import iii_conventions.test.s
-import org.junit.Assert.assertTrue
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.Test
 
 class N25ComparisonKtTest {
     /* Month numbering starts with 0 (0-Jan, 1-Feb, ... 11-Dec) */
-    @Test fun testDateComparison() {
+    @Test
+    fun testDateComparison() {
         assertTrue(task25(MyDate(2014, 1, 1), MyDate(2014, 1, 2)))
     }
 
-    @Test fun testBefore() {
+    @Test
+    fun testBefore() {
         val first = MyDate(2014, 5, 10)
         val second = MyDate(2014, 7, 11)
-        assertTrue("The date ${first.s} should be before ${second.s}", first < second)
+        assertTrue(first < second, "The date ${first.s} should be before ${second.s}")
     }
 
-    @Test fun testAfter() {
+    @Test
+    fun testAfter() {
         val first = MyDate(2014, 10, 20)
         val second = MyDate(2014, 7, 11)
-        assertTrue("The date ${first.s} should be after ${second.s}", first > second)
+        assertTrue(first > second, "The date ${first.s} should be after ${second.s}")
     }
 
     /* If you declare 'compareTo' as an extension function, remove this one to make the code compile */
diff --git a/test/iii_conventions/N26InRangeKtTest.kt b/test/iii_conventions/N26InRangeKtTest.kt
index e531b8a4e..71bda3ce0 100644
--- a/test/iii_conventions/N26InRangeKtTest.kt
+++ b/test/iii_conventions/N26InRangeKtTest.kt
@@ -1,49 +1,58 @@
 package iii_conventions
 
 import iii_conventions.test.s
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N26InRangeKtTest {
     fun doTest(date: MyDate, first: MyDate, last: MyDate, shouldBeInRange: Boolean) {
         val message = "The date ${date.s} should${if (shouldBeInRange) "" else "n't"} be in range: ${first.s}..${last.s}"
-        assertEquals(message, shouldBeInRange, checkInRange(date, first, last))
+        assertEquals(shouldBeInRange, checkInRange(date, first, last), message)
     }
 
     /* Month numbering starts with 0 (0-Jan, 1-Feb, ... 11-Dec) */
-    @Test fun testInRange() {
+    @Test
+    fun testInRange() {
         doTest(MyDate(2014, 3, 22), MyDate(2014, 1, 1), MyDate(2015, 1, 1), shouldBeInRange = true)
     }
 
-    @Test fun testBefore() {
+    @Test
+    fun testBefore() {
         doTest(MyDate(2013, 3, 22), MyDate(2014, 1, 1), MyDate(2015, 1, 1), shouldBeInRange = false)
     }
 
-    @Test fun testAfter() {
+    @Test
+    fun testAfter() {
         doTest(MyDate(2015, 3, 22), MyDate(2014, 1, 1), MyDate(2015, 1, 1), shouldBeInRange = false)
     }
 
-    @Test fun testEqualsToBegin() {
+    @Test
+    fun testEqualsToBegin() {
         doTest(MyDate(2014, 3, 22), MyDate(2014, 3, 22), MyDate(2015, 1, 1), shouldBeInRange = true)
     }
 
-    @Test fun testEqualsToEnd() {
+    @Test
+    fun testEqualsToEnd() {
         doTest(MyDate(2015, 1, 1), MyDate(2014, 3, 22), MyDate(2015, 1, 1), shouldBeInRange = true)
     }
 
-    @Test fun testInOneDayRange() {
+    @Test
+    fun testInOneDayRange() {
         doTest(MyDate(2015, 1, 1), MyDate(2015, 1, 1), MyDate(2015, 1, 1), shouldBeInRange = true)
     }
 
-    @Test fun testInvalidRange() {
+    @Test
+    fun testInvalidRange() {
         doTest(MyDate(2014, 2, 1), MyDate(2015, 1, 1), MyDate(2014, 1, 1), shouldBeInRange = false)
     }
 
-    @Test fun testInvalidRangeEqualsToBegin() {
+    @Test
+    fun testInvalidRangeEqualsToBegin() {
         doTest(MyDate(2015, 1, 1), MyDate(2015, 1, 1), MyDate(2014, 1, 1), shouldBeInRange = false)
     }
 
-    @Test fun testInvalidRangeEqualsToEnd() {
+    @Test
+    fun testInvalidRangeEqualsToEnd() {
         doTest(MyDate(2014, 1, 1), MyDate(2015, 1, 1), MyDate(2014, 1, 1), shouldBeInRange = false)
     }
 }
\ No newline at end of file
diff --git a/test/iii_conventions/N27RangeToKtTest.kt b/test/iii_conventions/N27RangeToKtTest.kt
index 761b4937f..1ec48e08a 100644
--- a/test/iii_conventions/N27RangeToKtTest.kt
+++ b/test/iii_conventions/N27RangeToKtTest.kt
@@ -1,25 +1,28 @@
 package iii_conventions
 
 import iii_conventions.test.s
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N27RangeToKtTest {
     fun doTest(date: MyDate, first: MyDate, last: MyDate, shouldBeInRange: Boolean) {
         val message = "The date ${date.s} should${if (shouldBeInRange) "" else "n't"} be in range: ${first.s}..${last.s}"
-        assertEquals(message, shouldBeInRange, checkInRange2(date, first, last))
+        assertEquals(shouldBeInRange, checkInRange2(date, first, last), message)
     }
 
     /* Month numbering starts with 0 (0-Jan, 1-Feb, ... 11-Dec) */
-    @Test fun testInRange() {
+    @Test
+    fun testInRange() {
         doTest(MyDate(2014, 3, 22), MyDate(2014, 1, 1), MyDate(2015, 1, 1), shouldBeInRange = true)
     }
 
-    @Test fun testBefore() {
+    @Test
+    fun testBefore() {
         doTest(MyDate(2013, 3, 22), MyDate(2014, 1, 1), MyDate(2015, 1, 1), shouldBeInRange = false)
     }
 
-    @Test fun testAfter() {
+    @Test
+    fun testAfter() {
         doTest(MyDate(2015, 3, 22), MyDate(2014, 1, 1), MyDate(2015, 1, 1), shouldBeInRange = false)
     }
 }
\ No newline at end of file
diff --git a/test/iii_conventions/N28ForLoopKtTest.kt b/test/iii_conventions/N28ForLoopKtTest.kt
index 8bde75d74..00620955e 100644
--- a/test/iii_conventions/N28ForLoopKtTest.kt
+++ b/test/iii_conventions/N28ForLoopKtTest.kt
@@ -1,49 +1,50 @@
 package iii_conventions
 
-import org.junit.Assert.assertEquals
-import org.junit.Assert.assertFalse
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertFalse
+import org.junit.jupiter.api.Test
 import java.util.*
 
 class N28ForLoopKtTest {
     /* Month numbering starts with 0 (0-Jan, 1-Feb, ... 11-Dec) */
 
-    @Test fun testIterateOverDateRange() {
+    @Test
+    fun testIterateOverDateRange() {
         val actualDateRange = ArrayList<MyDate>()
-        iterateOverDateRange(MyDate(2014, 5, 1), MyDate(2014, 5, 5), {
-            date: MyDate -> actualDateRange.add(date)
-        })
+        iterateOverDateRange(MyDate(2014, 5, 1), MyDate(2014, 5, 5)) { date: MyDate ->
+            actualDateRange.add(date)
+        }
         val expectedDateRange = arrayListOf(
-                MyDate(2014, 5, 1), MyDate(2014, 5, 2), MyDate(2014, 5, 3), MyDate(2014, 5, 4), MyDate(2014, 5, 5))
-        assertEquals("Incorrect iteration over five nice spring dates",
-                expectedDateRange, actualDateRange)
+            MyDate(2014, 5, 1), MyDate(2014, 5, 2), MyDate(2014, 5, 3), MyDate(2014, 5, 4), MyDate(2014, 5, 5))
+        assertEquals(expectedDateRange, actualDateRange, "Incorrect iteration over five nice spring dates")
     }
 
-    @Test fun testIterateOverEmptyRange() {
+    @Test
+    fun testIterateOverEmptyRange() {
         var invoked = false
         iterateOverDateRange(MyDate(2014, 1, 1), MyDate(2013, 1, 1), { invoked = true })
-        assertFalse("Handler was invoked on an empty range", invoked)
+        assertFalse(invoked, "Handler was invoked on an empty range")
     }
 
-    @Test fun testIterateOverLeapYearEndOfFebruary() {
+    @Test
+    fun testIterateOverLeapYearEndOfFebruary() {
         val actualDateRange = ArrayList<MyDate>()
-        iterateOverDateRange(MyDate(2016, 1, 26), MyDate(2016, 2, 1), {
-            date: MyDate -> actualDateRange.add(date)
-        })
+        iterateOverDateRange(MyDate(2016, 1, 26), MyDate(2016, 2, 1)) { date: MyDate ->
+            actualDateRange.add(date)
+        }
         val expectedDateRange = arrayListOf(
-                MyDate(2016, 1, 26), MyDate(2016, 1, 27), MyDate(2016, 1, 28), MyDate(2016, 1, 29), MyDate(2016, 2, 1))
-        assertEquals("Incorrect iteration over nice end of February of Leap-Year",
-                expectedDateRange, actualDateRange)
+            MyDate(2016, 1, 26), MyDate(2016, 1, 27), MyDate(2016, 1, 28), MyDate(2016, 1, 29), MyDate(2016, 2, 1))
+        assertEquals(expectedDateRange, actualDateRange, "Incorrect iteration over nice end of February of Leap-Year")
     }
 
-    @Test fun testIterateOverTheNewYear() {
+    @Test
+    fun testIterateOverTheNewYear() {
         val actualDateRange = ArrayList<MyDate>()
-        iterateOverDateRange(MyDate(2016, 11, 31), MyDate(2017, 0, 1), {
-            date: MyDate -> actualDateRange.add(date)
-        })
+        iterateOverDateRange(MyDate(2016, 11, 31), MyDate(2017, 0, 1)) { date: MyDate ->
+            actualDateRange.add(date)
+        }
         val expectedDateRange = arrayListOf(
-                MyDate(2016, 11, 31), MyDate(2017, 0, 1))
-        assertEquals("Incorrect iteration over the end of the year",
-                expectedDateRange, actualDateRange)
+            MyDate(2016, 11, 31), MyDate(2017, 0, 1))
+        assertEquals(expectedDateRange, actualDateRange, "Incorrect iteration over the end of the year")
     }
 }
\ No newline at end of file
diff --git a/test/iii_conventions/N29OperatorsOverloadingKtTest.kt b/test/iii_conventions/N29OperatorsOverloadingKtTest.kt
index d9629b7ed..90d52e72d 100644
--- a/test/iii_conventions/N29OperatorsOverloadingKtTest.kt
+++ b/test/iii_conventions/N29OperatorsOverloadingKtTest.kt
@@ -1,26 +1,30 @@
 package iii_conventions
 
 import iii_conventions.TimeInterval.*
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N29OperatorsOverloadingKtTest {
     /* Month numbering starts with 0 (0-Jan, 1-Feb, ... 11-Dec) */
-    @Test fun testAddTimeIntervals() {
+    @Test
+    fun testAddTimeIntervals() {
         assertEquals(MyDate(2014, 5, 22), MyDate(1983, 5, 22).addTimeIntervals(YEAR, 31))
         assertEquals(MyDate(1983, 5, 29), MyDate(1983, 5, 22).addTimeIntervals(DAY, 7))
         assertEquals(MyDate(1983, 5, 29), MyDate(1983, 5, 22).addTimeIntervals(WEEK, 1))
     }
 
-    @Test fun testAddOneTimeInterval() {
+    @Test
+    fun testAddOneTimeInterval() {
         assertEquals(MyDate(2015, 5, 8), task29_1(MyDate(2014, 5, 1)))
     }
 
-    @Test fun testOneMonth() {
+    @Test
+    fun testOneMonth() {
         assertEquals(MyDate(2016, 0, 27), task29_2(MyDate(2014, 0, 1)))
     }
 
-    @Test fun testMonthChange() {
+    @Test
+    fun testMonthChange() {
         assertEquals(MyDate(2016, 1, 20), task29_2(MyDate(2014, 0, 25)))
     }
 }
\ No newline at end of file
diff --git a/test/iii_conventions/N30DestructuringDeclarationsKtTest.kt b/test/iii_conventions/N30DestructuringDeclarationsKtTest.kt
index 51278ee06..71c9b8ff9 100644
--- a/test/iii_conventions/N30DestructuringDeclarationsKtTest.kt
+++ b/test/iii_conventions/N30DestructuringDeclarationsKtTest.kt
@@ -1,11 +1,12 @@
 package iii_conventions.multiAssignemnt
 
-import org.junit.Assert.assertFalse
-import org.junit.Assert.assertTrue
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertFalse
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.Test
 
 class N30DestructuringDeclarationsKtTest {
-    @Test fun testIsLeapDay() {
+    @Test
+    fun testIsLeapDay() {
         assertTrue(isLeapDay(MyDate(2016, 1, 29)))
         assertFalse(isLeapDay(MyDate(2015, 1, 29)))
     }
diff --git a/test/iii_conventions/N31InvokeKtTest.kt b/test/iii_conventions/N31InvokeKtTest.kt
index e732455e7..c4f995ad4 100644
--- a/test/iii_conventions/N31InvokeKtTest.kt
+++ b/test/iii_conventions/N31InvokeKtTest.kt
@@ -1,18 +1,20 @@
 package iii_conventions
 
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N31InvokeKtTest {
-    @Test fun testTask17() {
+    @Test
+    fun testTask17() {
         assertEquals(4, task31(Invokable()))
     }
 
-    @Test fun testNumberOfInvocations() {
+    @Test
+    fun testNumberOfInvocations() {
         val message = "The number of invocations is incorrect"
         fun testInvokable(numberOfInvocations: Int, invokeSeveralTimes: (Invokable) -> Invokable) {
             val invokable = Invokable()
-            assertEquals(message, numberOfInvocations, invokeSeveralTimes(invokable).getNumberOfInvocations())
+            assertEquals(numberOfInvocations, invokeSeveralTimes(invokable).getNumberOfInvocations(), message)
         }
 
         testInvokable(1) { it() }
diff --git a/test/iv_properties/N32PropertiesKtTest.kt b/test/iv_properties/N32PropertiesKtTest.kt
index 6bfbc2f4a..0a19ba676 100644
--- a/test/iv_properties/N32PropertiesKtTest.kt
+++ b/test/iv_properties/N32PropertiesKtTest.kt
@@ -1,18 +1,18 @@
 package iv_properties
 
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N32PropertiesKtTest {
-    @Test fun testPropertyWithCounter() {
+    @Test
+    fun testPropertyWithCounter() {
         val q = PropertyExample()
         q.propertyWithCounter = 14
         q.propertyWithCounter = 21
         q.propertyWithCounter = 32
-        assertEquals("The property q.counter should contain the number of assignments to q.propertyWithCounter:",
-                3, q.counter)
+        assertEquals(3, q.counter, "The property q.counter should contain the number of assignments to q.propertyWithCounter:")
         // Here we have to use !! due to false smart cast impossible
-        assertEquals("The property q.propertyWithCounter should be set:", 32, q.propertyWithCounter!!)
+        assertEquals(32, q.propertyWithCounter!!, "The property q.propertyWithCounter should be set:")
     }
 
 }
\ No newline at end of file
diff --git a/test/iv_properties/N33LazyPropertyKtTest.kt b/test/iv_properties/N33LazyPropertyKtTest.kt
index 32bf4e6bf..c54eb2096 100644
--- a/test/iv_properties/N33LazyPropertyKtTest.kt
+++ b/test/iv_properties/N33LazyPropertyKtTest.kt
@@ -1,24 +1,26 @@
 package iv_properties
 
-import org.junit.Assert.*
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.*
+import org.junit.jupiter.api.Test
 
 class N33LazyPropertyKtTest {
-    @Test fun testLazy() {
+    @Test
+    fun testLazy() {
         var initialized = false
-        val lazyProperty = LazyProperty({ initialized = true; 42 })
-        assertFalse("Property shouldn't be initialized before access", initialized)
+        val lazyProperty = LazyProperty { initialized = true; 42 }
+        assertFalse(initialized, "Property shouldn't be initialized before access")
         val result: Int = lazyProperty.lazy
-        assertTrue("Property should be initialized after access", initialized)
+        assertTrue(initialized, "Property should be initialized after access")
         assertEquals(42, result)
     }
 
-    @Test fun initializedOnce() {
+    @Test
+    fun initializedOnce() {
         var initialized = 0
-        val lazyProperty = LazyProperty( { initialized++; 42 })
+        val lazyProperty = LazyProperty({ initialized++; 42 })
         lazyProperty.lazy
         lazyProperty.lazy
-        assertEquals("Lazy property should be initialized once", 1, initialized)
+        assertEquals(1, initialized, "Lazy property should be initialized once")
 
     }
 }
diff --git a/test/iv_properties/N34DelegatesExamplesKtTest.kt b/test/iv_properties/N34DelegatesExamplesKtTest.kt
index 8f2ecdf68..812a3b23b 100644
--- a/test/iv_properties/N34DelegatesExamplesKtTest.kt
+++ b/test/iv_properties/N34DelegatesExamplesKtTest.kt
@@ -1,24 +1,26 @@
 package iv_properties
 
-import org.junit.Assert.*
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.*
+import org.junit.jupiter.api.Test
 
 class N34DelegatesExamplesKtTest {
-    @Test fun testLazy() {
+    @Test
+    fun testLazy() {
         var initialized = false
-        val lazyProperty = LazyPropertyUsingDelegates({ initialized = true; 42 })
-        assertFalse("Property shouldn't be initialized before access", initialized)
+        val lazyProperty = LazyPropertyUsingDelegates { initialized = true; 42 }
+        assertFalse(initialized, "Property shouldn't be initialized before access")
         val result: Int = lazyProperty.lazyValue
-        assertTrue("Property should be initialized after access", initialized)
+        assertTrue(initialized, "Property should be initialized after access")
         assertEquals(42, result)
     }
 
-    @Test fun initializedOnce() {
+    @Test
+    fun initializedOnce() {
         var initialized = 0
-        val lazyProperty = LazyPropertyUsingDelegates( { initialized++; 42 })
+        val lazyProperty = LazyPropertyUsingDelegates { initialized++; 42 }
         lazyProperty.lazyValue
         lazyProperty.lazyValue
-        assertEquals("Lazy property should be initialized once", 1, initialized)
+        assertEquals(1, initialized, "Lazy property should be initialized once")
 
     }
 }
\ No newline at end of file
diff --git a/test/iv_properties/N35HowDelegatesWorkKtTest.kt b/test/iv_properties/N35HowDelegatesWorkKtTest.kt
index 24321527e..492b6e6b8 100644
--- a/test/iv_properties/N35HowDelegatesWorkKtTest.kt
+++ b/test/iv_properties/N35HowDelegatesWorkKtTest.kt
@@ -1,11 +1,12 @@
 package iv_properties
 
 import iii_conventions.MyDate
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N35HowDelegatesWorkKtTest {
-    @Test fun testDate() {
+    @Test
+    fun testDate() {
         val d = D()
         /* Month numbering starts with 0 (0-Jan, 1-Feb, ... 11-Dec) */
         d.date = MyDate(2014, 1, 13)
diff --git a/test/util/AdditionalTest.kt b/test/util/AdditionalTest.kt
index 53a729d40..204005aa0 100644
--- a/test/util/AdditionalTest.kt
+++ b/test/util/AdditionalTest.kt
@@ -6,28 +6,29 @@ import i_introduction._4_Lambdas.N04LambdasKtTest
 import i_introduction._7_Nullable_Types.N07NullableTypesKtTest
 import i_introduction._8_Smart_Casts.N08SmartCastsKtTest
 import ii_collections.N24ExtensionsOnCollectionsKtTest
-import org.junit.Assert.assertTrue
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.Test
 
 class AdditionalTest {
-    @Test fun test() {
+    @Test
+    fun test() {
         invokeTests(
-                { N01JavaToKotlinConverterKtTest().collection() },
-                { N03DefaultArgumentsKtTest().testDefaultAndNamedParams() },
-                { N04LambdasKtTest().contains() },
-                { N07NullableTypesKtTest().everythingIsOk() },
-                { N08SmartCastsKtTest().testNum() },
-                { N24ExtensionsOnCollectionsKtTest().testCollectionOfOneElement() }
+            { N01JavaToKotlinConverterKtTest().collection() },
+            { N03DefaultArgumentsKtTest().testDefaultAndNamedParams() },
+            { N04LambdasKtTest().contains() },
+            { N07NullableTypesKtTest().everythingIsOk() },
+            { N08SmartCastsKtTest().testNum() },
+            { N24ExtensionsOnCollectionsKtTest().testCollectionOfOneElement() }
         )
-        assertTrue("${JavaCode.set}", JavaCode.set.isEmpty())
+        assertTrue(JavaCode.set.isEmpty(), "${JavaCode.set}")
     }
 
     private fun invokeTests(vararg tests: () -> Unit) {
         for (test in tests) {
             try {
                 test()
+            } catch (e: NotImplementedException) {
             }
-            catch (e: NotImplementedException) {}
         }
     }
 }
diff --git a/test/v_builders/N36ExtensionFunctionLiteralsKtTest.kt b/test/v_builders/N36ExtensionFunctionLiteralsKtTest.kt
index bcf60fe92..48b95e514 100644
--- a/test/v_builders/N36ExtensionFunctionLiteralsKtTest.kt
+++ b/test/v_builders/N36ExtensionFunctionLiteralsKtTest.kt
@@ -1,13 +1,13 @@
 package v_builders
 
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N36ExtensionFunctionLiteralsKtTest {
-    @Test fun testIsOddAndIsEven() {
+    @Test
+    fun testIsOddAndIsEven() {
         val result = task36()
-        assertEquals("The functions 'isOdd' and 'isEven' should be implemented correctly",
-                listOf(false, true, true), result)
+        assertEquals(listOf(false, true, true), result, "The functions 'isOdd' and 'isEven' should be implemented correctly")
 
     }
 }
\ No newline at end of file
diff --git a/test/v_builders/N37StringAndMapBuildersKtTest.kt b/test/v_builders/N37StringAndMapBuildersKtTest.kt
index 5afed6f47..5c2a4700e 100644
--- a/test/v_builders/N37StringAndMapBuildersKtTest.kt
+++ b/test/v_builders/N37StringAndMapBuildersKtTest.kt
@@ -1,16 +1,17 @@
 package v_builders
 
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 import java.util.*
 
 class N37StringAndMapBuildersKtTest {
-    @Test fun testBuildMap() {
+    @Test
+    fun testBuildMap() {
         val map = task37()
         val expected = HashMap<Int, String>()
         for (i in 0..10) {
             expected[i] = "$i"
         }
-        assertEquals("Map should be filled with the right values", expected, map)
+        assertEquals(expected, map, "Map should be filled with the right values")
     }
 }
\ No newline at end of file
diff --git a/test/v_builders/N38TheFunctionApplyKtTest.kt b/test/v_builders/N38TheFunctionApplyKtTest.kt
index 222a3d2a5..2c939e935 100644
--- a/test/v_builders/N38TheFunctionApplyKtTest.kt
+++ b/test/v_builders/N38TheFunctionApplyKtTest.kt
@@ -1,11 +1,12 @@
 package v_builders.examples
 
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 import java.util.*
 
 class N38TheFunctionApplyKtTest {
-    @Test fun testBuildString() {
+    @Test
+    fun testBuildString() {
         val expected = StringBuilder().apply {
             append("Numbers: ")
             for (i in 1..10) {
@@ -13,10 +14,11 @@ class N38TheFunctionApplyKtTest {
             }
         }.toString()
         val actual = buildString()
-        assertEquals("String should be built:", expected, actual)
+        assertEquals(expected, actual, "String should be built:")
     }
 
-    @Test fun testBuildMap() {
+    @Test
+    fun testBuildMap() {
         val expected = HashMap<Int, String>().apply {
             put(0, "0")
             for (i in 1..10) {
@@ -24,6 +26,6 @@ class N38TheFunctionApplyKtTest {
             }
         }
         val actual = buildMap()
-        assertEquals("Map should be filled with the right values", expected, actual)
+        assertEquals(expected, actual, "Map should be filled with the right values")
     }
 }
diff --git a/test/v_builders/N39HtmlBuildersKtTest.kt b/test/v_builders/N39HtmlBuildersKtTest.kt
index 806b47932..58c3b09f1 100644
--- a/test/v_builders/N39HtmlBuildersKtTest.kt
+++ b/test/v_builders/N39HtmlBuildersKtTest.kt
@@ -1,16 +1,18 @@
 package v_builders
 
-import org.junit.Assert.assertTrue
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.Test
 
 class N39HtmlBuildersKtTest {
-    @Test fun productTableIsFilled() {
+    @Test
+    fun productTableIsFilled() {
         val result = renderProductTable()
-        assertTrue("Product table should contain corresponding data", result.contains("cactus"))
+        assertTrue(result.contains("cactus"), "Product table should contain corresponding data")
     }
 
-    @Test fun productTableIsColored() {
+    @Test
+    fun productTableIsColored() {
         val result = renderProductTable()
-        assertTrue("Product table should be colored", result.contains("bgcolor"))
+        assertTrue(result.contains("bgcolor"), "Product table should be colored")
     }
 }
diff --git a/test/v_builders/N40BuildersHowItWorksKtTest.kt b/test/v_builders/N40BuildersHowItWorksKtTest.kt
index 525b172a3..7a50d8092 100644
--- a/test/v_builders/N40BuildersHowItWorksKtTest.kt
+++ b/test/v_builders/N40BuildersHowItWorksKtTest.kt
@@ -1,13 +1,14 @@
 package v_builders
 
-import org.junit.Assert.fail
-import org.junit.Test
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.fail
 import util.questions.Answer.b
 import util.questions.Answer.c
 import v_builders.builders.task40
 
 class N40BuildersHowItWorksKtTest {
-    @Test fun testBuildersQuiz() {
+    @Test
+    fun testBuildersQuiz() {
         val answers = task40()
         if (answers.values.toSet() == setOf(null)) {
             fail("Please specify your answers!")
diff --git a/test/vi_generics/N41GenericFunctionsKtTest.kt b/test/vi_generics/N41GenericFunctionsKtTest.kt
index bacab18b3..329573c91 100644
--- a/test/vi_generics/N41GenericFunctionsKtTest.kt
+++ b/test/vi_generics/N41GenericFunctionsKtTest.kt
@@ -1,16 +1,18 @@
 package vi_generics
 
-import org.junit.Assert.assertEquals
-import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 
 class N41GenericFunctionsKtTest {
-    @Test fun testPartitionWordsAndLines() {
+    @Test
+    fun testPartitionWordsAndLines() {
         val (words, lines) = listOf("a", "a b", "c", "d e").partitionWordsAndLines()
         assertEquals(listOf("a", "c"), words)
         assertEquals(listOf("a b", "d e"), lines)
     }
 
-    @Test fun testPartitionLettersAndOtherSymbols() {
+    @Test
+    fun testPartitionLettersAndOtherSymbols() {
         val (letters, other) = setOf('a', '%', 'r', '}').partitionLettersAndOtherSymbols()
         assertEquals(setOf('a', 'r'), letters)
         assertEquals(setOf('%', '}'), other)