Add LRUMapExamples

Author: robertsmieja

src/test/java/com/robertsmieja/example/apache/commons/collections4/LRUMapExamples.java

@@ -0,0 +1,93 @@
+package com.robertsmieja.example.apache.commons.collections4;
+
+import org.apache.commons.collections4.map.LRUMap;
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+
+/**
+ * Examples demonstrating the LRUMap
+ */
+public class LRUMapExamples {
+    LRUMap<Integer, String> lruMap;
+
+    @Before
+    public void setup(){
+        lruMap = new LRUMap<>(2);
+    }
+
+    @Test
+    public void maxSize(){
+        assertEquals(lruMap.size(), 0);
+        assertEquals(lruMap.maxSize(), 2);
+    }
+
+    @Test
+    public void anythingUnderTheMaxSizeStaysInTheMap(){
+        lruMap.put(1, "foo");
+        lruMap.put(2, "bar");
+
+        assertEquals(lruMap.get(1), "foo");
+        assertEquals(lruMap.get(2), "bar");
+    }
+
+    @Test
+    public void goingOverTheMaxKicksOutTheOldestEntry(){
+        lruMap.put(1, "foo");
+        lruMap.put(2, "bar");
+
+        assertEquals(lruMap.get(1), "foo");
+        assertEquals(lruMap.get(2), "bar");
+
+        //A put now show remove the entry (1, "foo")
+        lruMap.put(3, "is it gone?");
+
+        assertFalse(lruMap.containsKey(1));
+        assertNull(lruMap.get(1));
+        assertEquals(lruMap.size(), 2);
+
+        assertEquals(lruMap.get(2), "bar");
+        assertEquals(lruMap.get(3), "is it gone?");
+    }
+
+    @Test
+    public void goingOverTheMaxKicksOutTheOldestEntry_exceptThisTimeWithTheSecondEntry(){
+        lruMap.put(1, "foo");
+        lruMap.put(2, "bar");
+
+        assertEquals(lruMap.get(2), "bar");
+        assertEquals(lruMap.get(1), "foo");
+
+        //A put now show remove the entry (1, "foo")
+        lruMap.put(3, "is it gone?");
+
+        assertFalse(lruMap.containsKey(2));
+        assertNull(lruMap.get(2));
+        assertEquals(lruMap.size(), 2);
+
+        assertEquals(lruMap.get(1), "foo");
+        assertEquals(lruMap.get(3), "is it gone?");
+    }
+
+    @Test
+    public void passingInFalseDoesntUpdateTheInternalMru(){
+        lruMap.put(1, "foo");
+        lruMap.put(2, "bar");
+
+        assertEquals(lruMap.get(2), "bar");
+        assertEquals(lruMap.get(1, false), "foo");
+
+        //A put now show remove the entry (1, "foo")
+        lruMap.put(3, "is it gone?");
+
+        assertFalse(lruMap.containsKey(1));
+        assertNull(lruMap.get(1));
+        assertEquals(lruMap.size(), 2);
+
+        assertEquals(lruMap.get(2), "bar");
+        assertEquals(lruMap.get(3), "is it gone?");
+    }
+}