Add test for detached ArrayBuffer (swiftwasm#154)

Author: yonihemi

Diff for: IntegrationTests/TestSuites/Package.swift

@@ -23,7 +23,11 @@ let package = Package(
     ],
     dependencies: [.package(name: "JavaScriptKit", path: "../../")],
     targets: [
-        .target(name: "PrimaryTests", dependencies: ["JavaScriptKit"]),
+        .target(name: "CHelpers"),
+        .target(name: "PrimaryTests", dependencies: [
+            "JavaScriptKit",
+            "CHelpers",
+        ]),
         .target(
             name: "ConcurrencyTests",
             dependencies: [

Diff for: IntegrationTests/TestSuites/Sources/CHelpers/helpers.c

@@ -0,0 +1,4 @@
+int growMemory(int pages) {
+    return __builtin_wasm_memory_grow(0, pages);
+}
+

Diff for: IntegrationTests/TestSuites/Sources/CHelpers/include/helpers.h

@@ -0,0 +1,5 @@
+/// Ask host to grow WebAssembly module's allocated memory
+///
+/// @param pages Number of memory pages to increase memory by.
+int growMemory(int pages);
+

Diff for: IntegrationTests/TestSuites/Sources/CHelpers/include/module.modulemap

@@ -0,0 +1,4 @@
+module CHelpers {
+    header "helpers.h"
+    export *
+}

Diff for: IntegrationTests/TestSuites/Sources/PrimaryTests/main.swift

@@ -1,5 +1,5 @@
 import JavaScriptKit
-
+import CHelpers
 
 try test("Literal Conversion") {
     let global = JSObject.global
@@ -735,4 +735,15 @@ try test("Exception") {
     try expectNotNil(errorObject3)
 }
 
+/// If WebAssembly.Memory is not accessed correctly (i.e. creating a new view each time),
+/// this test will fail with `TypeError: Cannot perform Construct on a detached ArrayBuffer`,
+/// since asking to grow memory will detach the backing ArrayBuffer.
+/// See https://github.com/swiftwasm/JavaScriptKit/pull/153
+try test("Grow Memory") {
+    let string = "Hello"
+    let jsString = JSValue.string(string)
+    growMemory(1)
+    try expectEqual(string, jsString.description)
+}
+
 Expectation.wait(expectations)