Add unit test target for JavaScriptEventLoopTestSupport

Author: kateinoigakukun

Diff for: Package.swift

@@ -31,9 +31,16 @@ let package = Package(
             name: "JavaScriptEventLoopTestSupport",
             dependencies: [
                 "_CJavaScriptEventLoopTestSupport",
-                .product(name: "JavaScriptEventLoop", package: "JavaScriptKit"),
+                "JavaScriptEventLoop",
             ]
         ),
         .target(name: "_CJavaScriptEventLoopTestSupport"),
+        .testTarget(
+          name: "JavaScriptEventLoopTestSupportTests",
+          dependencies: [
+            "JavaScriptKit",
+            "JavaScriptEventLoopTestSupport"
+          ]
+        ),
     ]
 )

Diff for: Tests/JavaScriptEventLoopTestSupportTests/JavaScriptEventLoopTestSupportTests.swift

@@ -0,0 +1,15 @@
+import XCTest
+import JavaScriptKit
+
+final class JavaScriptEventLoopTestSupportTests: XCTestCase {
+    func testAwaitMicrotask() async {
+        let _: () = await withCheckedContinuation { cont in
+            JSObject.global.queueMicrotask.function!(
+                JSOneshotClosure { _ in
+                    cont.resume(returning: ())
+                    return .undefined
+                }
+            )
+        }
+    }
+}

Diff for: scripts/test-harness.js

@@ -0,0 +1,10 @@
+Error.stackTraceLimit = Infinity;
+
+const { startWasiTask, WASI } = require("../IntegrationTests/lib");
+
+const handleExitOrError = (error) => {
+  console.log(error);
+  process.exit(1);
+}
+
+startWasiTask(process.argv[2]).catch(handleExitOrError);