From 7d78e4e0fcb513ab290cf53687e81461394a3354 Mon Sep 17 00:00:00 2001
From: Rikito Taniguchi <rikiriki1238@gmail.com>
Date: Fri, 15 Mar 2024 15:57:11 +0900
Subject: [PATCH] test: Remove `@JSExportTopLevel` from test-suites functions

Previously, the resulting Wasm module contained all the code for every test-suite package,
which made debugging test results harder because
(1) the resulting Wasm module contained a lot of irrelevant code, and
(2) if one of the test-suites was compiled to invalid Wasm code, all the tests would be affected, rendering all modules unable to instantiate.

This issue caused because each Scala.js package in the test-suites containing
`@JSExportTopLevel`, which served as a root node for reachability analysis.
Thus, all the code under test-suites remained alive after linking.

To address this, this commit removes all `@JSExportTopLevel` from the test-suites.
Instead, we added a function call to the `ModuleInitializer` methods into
the start function of Wasm
If a test fails, Wasm will execute unreachable, causing instantiation to fail and the test to fail accordingly.
---
 cli/src/main/scala/Main.scala                 |  10 +-
 cli/src/main/scala/TestSuites.scala           |  23 ++--
 .../src/main/scala/testsuite/Assert.scala     |  17 +++
 .../src/main/scala/testsuite/core/Add.scala   |  10 +-
 .../testsuite/core/AsInstanceOfTest.scala     |  17 ++-
 .../core/HijackedClassesDispatchTest.scala    |  67 +++++-----
 .../core/HijackedClassesMonoTest.scala        |  17 ++-
 .../core/HijackedClassesUpcastTest.scala      |  32 ++---
 .../scala/testsuite/core/InterfaceCall.scala  |  11 +-
 .../scala/testsuite/core/JSInteropTest.scala  | 115 +++++++++---------
 .../main/scala/testsuite/core/Simple.scala    |  10 +-
 .../scala/testsuite/core/ToStringTest.scala   |  77 ++++++------
 .../testsuite/core/VirtualDispatch.scala      |  21 ++--
 tests/src/test/scala/tests/CoreTests.scala    |  19 ++-
 wasm/src/main/scala/Compiler.scala            |   2 +-
 wasm/src/main/scala/wasm4s/WasmContext.scala  |  53 ++++++--
 16 files changed, 272 insertions(+), 229 deletions(-)
 create mode 100644 test-suite/src/main/scala/testsuite/Assert.scala

diff --git a/cli/src/main/scala/Main.scala b/cli/src/main/scala/Main.scala
index 708a41b6..a0d84d68 100644
--- a/cli/src/main/scala/Main.scala
+++ b/cli/src/main/scala/Main.scala
@@ -28,17 +28,11 @@ object Main {
 
     val result =
       if (mode == "testsuite") {
-        val className = TestSuites.suites.map(_.className)
-        val moduleInitializers = className
-          .map { clazz =>
-            ModuleInitializer.mainMethod(clazz, "main")
-          }
-          .zip(className)
-
         for {
           irFiles <- new CliReader(classpath).irFiles
           _ <- Future.sequence {
-            moduleInitializers.map { case (moduleInitializer, className) =>
+            TestSuites.suites.map { case TestSuites.TestSuite(className, methodName) =>
+              val moduleInitializer = ModuleInitializer.mainMethod(className, methodName)
               Compiler.compileIRFiles(
                 irFiles,
                 List(moduleInitializer),
diff --git a/cli/src/main/scala/TestSuites.scala b/cli/src/main/scala/TestSuites.scala
index cdd45a3c..86631719 100644
--- a/cli/src/main/scala/TestSuites.scala
+++ b/cli/src/main/scala/TestSuites.scala
@@ -1,18 +1,17 @@
 package cli
 
 object TestSuites {
-  case class TestSuite(className: String, methodName: String)
+  case class TestSuite(className: String, methodName: String = "main")
   val suites = List(
-    TestSuite("testsuite.core.simple.Simple", "simple"),
-    TestSuite("testsuite.core.add.Add", "add"),
-    TestSuite("testsuite.core.add.Add", "add"),
-    TestSuite("testsuite.core.virtualdispatch.VirtualDispatch", "virtualDispatch"),
-    TestSuite("testsuite.core.interfacecall.InterfaceCall", "interfaceCall"),
-    TestSuite("testsuite.core.asinstanceof.AsInstanceOfTest", "asInstanceOf"),
-    TestSuite("testsuite.core.jsinterop.JSInteropTest", "jsInterop"),
-    TestSuite("testsuite.core.hijackedclassesdispatch.HijackedClassesDispatchTest", "hijackedClassesDispatch"),
-    TestSuite("testsuite.core.hijackedclassesmono.HijackedClassesMonoTest", "hijackedClassesMono"),
-    TestSuite("testsuite.core.hijackedclassesupcast.HijackedClassesUpcastTest", "hijackedClassesUpcast"),
-    TestSuite("testsuite.core.tostring.ToStringTest", "toStringConversions")
+    TestSuite("testsuite.core.Simple"),
+    TestSuite("testsuite.core.Add"),
+    TestSuite("testsuite.core.VirtualDispatch"),
+    TestSuite("testsuite.core.InterfaceCall"),
+    TestSuite("testsuite.core.AsInstanceOfTest"),
+    TestSuite("testsuite.core.JSInteropTest"),
+    TestSuite("testsuite.core.HijackedClassesDispatchTest"),
+    TestSuite("testsuite.core.HijackedClassesMonoTest"),
+    TestSuite("testsuite.core.HijackedClassesUpcastTest"),
+    TestSuite("testsuite.core.ToStringTest")
   )
 }
diff --git a/test-suite/src/main/scala/testsuite/Assert.scala b/test-suite/src/main/scala/testsuite/Assert.scala
new file mode 100644
index 00000000..fb0467fe
--- /dev/null
+++ b/test-suite/src/main/scala/testsuite/Assert.scala
@@ -0,0 +1,17 @@
+package testsuite
+
+/** Temporary assertion method on Scala for Wasm. `ok` method generates `unreachable` if the given
+  * condition is false, trapping at runtime.
+  *
+  * While it's desirable to eventually utilize Scala's assertion, it's currently unavailable because
+  * we cannot compile Throwable to wasm yet, thus throw new (Throwable) is unusable. and making
+  * assert unavailable as well.
+  *
+  * Using JS's assert isn't feasible either; `console.assert` merely displays a message when
+  * assertion failure, and Node's assert module is unsupported for Wasm due to current
+  * unavailability of `JSImport` and module.
+  */
+object Assert {
+  def ok(cond: Boolean): Unit =
+    if (!cond) null.toString() // Apply to Null should compile to unreachable
+}
diff --git a/test-suite/src/main/scala/testsuite/core/Add.scala b/test-suite/src/main/scala/testsuite/core/Add.scala
index 57fcc238..53e6399a 100644
--- a/test-suite/src/main/scala/testsuite/core/Add.scala
+++ b/test-suite/src/main/scala/testsuite/core/Add.scala
@@ -1,11 +1,9 @@
-package testsuite.core.add
+package testsuite.core
 
-import scala.scalajs.js.annotation._
+import testsuite.Assert.ok
 
 object Add {
-  def main(): Unit = { val _ = test() }
-  @JSExportTopLevel("add")
-  def test(): Boolean = {
-    1 + 1 == 2
+  def main(): Unit = {
+    ok(1 + 1 == 2)
   }
 }
diff --git a/test-suite/src/main/scala/testsuite/core/AsInstanceOfTest.scala b/test-suite/src/main/scala/testsuite/core/AsInstanceOfTest.scala
index a3f0c06e..f48ba454 100644
--- a/test-suite/src/main/scala/testsuite/core/AsInstanceOfTest.scala
+++ b/test-suite/src/main/scala/testsuite/core/AsInstanceOfTest.scala
@@ -1,15 +1,14 @@
-package testsuite.core.asinstanceof
+package testsuite.core
 
-import scala.scalajs.js.annotation._
+import testsuite.Assert.ok
 
 object AsInstanceOfTest {
-  def main(): Unit = { val _ = test() }
-
-  @JSExportTopLevel("asInstanceOf")
-  def test(): Boolean = {
-    testInt(5) &&
-      testClasses(new Child()) &&
-      testString("foo", true)
+  def main(): Unit = {
+    ok(
+      testInt(5) &&
+        testClasses(new Child()) &&
+        testString("foo", true)
+    )
   }
 
   def testClasses(c: Child): Boolean = {
diff --git a/test-suite/src/main/scala/testsuite/core/HijackedClassesDispatchTest.scala b/test-suite/src/main/scala/testsuite/core/HijackedClassesDispatchTest.scala
index 91f1ce3f..9f273b7b 100644
--- a/test-suite/src/main/scala/testsuite/core/HijackedClassesDispatchTest.scala
+++ b/test-suite/src/main/scala/testsuite/core/HijackedClassesDispatchTest.scala
@@ -1,44 +1,43 @@
-package testsuite.core.hijackedclassesdispatch
+package testsuite.core
 
-import scala.scalajs.js.annotation._
+import testsuite.Assert.ok
 
 object HijackedClassesDispatchTest {
-  def main(): Unit = { val _ = test() }
-
-  @JSExportTopLevel("hijackedClassesDispatch")
-  def test(): Boolean = {
+  def main(): Unit = {
     val obj = new Test()
     val otherObj = new Test()
     val obj2 = new Test2()
     val otherObj2 = new Test2()
-    testToString(true, "true") &&
-      testToString(54321, "54321") &&
-      testToString(obj, "Test class") &&
-      testToString(obj2, "[object]") &&
-      testToString('A', "A") &&
-      testHashCode(true, 1231) &&
-      testHashCode(54321, 54321) &&
-      testHashCode("foo", 101574) &&
-      testHashCode(obj, 123) &&
-      testHashCode(obj2, 42) &&
-      testHashCode('A', 65) &&
-      testIntValue(Int.box(5), 5) &&
-      testIntValue(Long.box(6L), 6) &&
-      testIntValue(Double.box(7.5), 7) &&
-      testIntValue(new CustomNumber(), 789) &&
-      testLength("foo", 3) &&
-      testLength(new CustomCharSeq(), 54) &&
-      testCharAt("foobar", 3, 'b') &&
-      testCharAt(new CustomCharSeq(), 3, 'A') &&
-      testEquals(true, 1, false) &&
-      testEquals(1.0, 1, true) &&
-      testEquals("foo", "foo", true) &&
-      testEquals("foo", "bar", false) &&
-      testEquals(obj, obj2, false) &&
-      testEquals(obj, otherObj, true) &&
-      testEquals(obj2, otherObj2, false) &&
-      testNotifyAll(true) &&
-      testNotifyAll(obj)
+    ok(
+      testToString(true, "true") &&
+        testToString(54321, "54321") &&
+        testToString(obj, "Test class") &&
+        testToString(obj2, "[object]") &&
+        testToString('A', "A") &&
+        testHashCode(true, 1231) &&
+        testHashCode(54321, 54321) &&
+        testHashCode("foo", 101574) &&
+        testHashCode(obj, 123) &&
+        testHashCode(obj2, 42) &&
+        testHashCode('A', 65) &&
+        testIntValue(Int.box(5), 5) &&
+        testIntValue(Long.box(6L), 6) &&
+        testIntValue(Double.box(7.5), 7) &&
+        testIntValue(new CustomNumber(), 789) &&
+        testLength("foo", 3) &&
+        testLength(new CustomCharSeq(), 54) &&
+        testCharAt("foobar", 3, 'b') &&
+        testCharAt(new CustomCharSeq(), 3, 'A') &&
+        testEquals(true, 1, false) &&
+        testEquals(1.0, 1, true) &&
+        testEquals("foo", "foo", true) &&
+        testEquals("foo", "bar", false) &&
+        testEquals(obj, obj2, false) &&
+        testEquals(obj, otherObj, true) &&
+        testEquals(obj2, otherObj2, false) &&
+        testNotifyAll(true) &&
+        testNotifyAll(obj)
+    )
   }
 
   def testToString(x: Any, expected: String): Boolean =
diff --git a/test-suite/src/main/scala/testsuite/core/HijackedClassesMonoTest.scala b/test-suite/src/main/scala/testsuite/core/HijackedClassesMonoTest.scala
index 45f2106b..a915ea4c 100644
--- a/test-suite/src/main/scala/testsuite/core/HijackedClassesMonoTest.scala
+++ b/test-suite/src/main/scala/testsuite/core/HijackedClassesMonoTest.scala
@@ -1,14 +1,13 @@
-package testsuite.core.hijackedclassesmono
+package testsuite.core
 
-import scala.scalajs.js.annotation._
+import testsuite.Assert.ok
 
 object HijackedClassesMonoTest {
-  def main(): Unit = { val _ = test() }
-
-  @JSExportTopLevel("hijackedClassesMono")
-  def test(): Boolean = {
-    testInteger(5) &&
-      testString("foo")
+  def main(): Unit = {
+    ok(
+      testInteger(5) &&
+        testString("foo")
+    )
   }
 
   def testInteger(x: Int): Boolean = {
@@ -17,6 +16,6 @@ object HijackedClassesMonoTest {
 
   def testString(foo: String): Boolean = {
     foo.length() == 3 &&
-      foo.hashCode() == 101574
+    foo.hashCode() == 101574
   }
 }
diff --git a/test-suite/src/main/scala/testsuite/core/HijackedClassesUpcastTest.scala b/test-suite/src/main/scala/testsuite/core/HijackedClassesUpcastTest.scala
index 09830703..f6015a98 100644
--- a/test-suite/src/main/scala/testsuite/core/HijackedClassesUpcastTest.scala
+++ b/test-suite/src/main/scala/testsuite/core/HijackedClassesUpcastTest.scala
@@ -1,18 +1,18 @@
-package testsuite.core.hijackedclassesupcast
+package testsuite.core
 
-import scala.scalajs.js.annotation._
+import testsuite.Assert.ok
 
 object HijackedClassesUpcastTest {
-  def main(): Unit = { val _ = test() }
+  def main(): Unit = {
+    ok(
+      testBoolean(true) &&
+        testInteger(5) &&
+        testIntegerNull(null) &&
+        testString("foo") &&
+        testStringNull(null) &&
+        testCharacter('A')
+    )
 
-  @JSExportTopLevel("hijackedClassesUpcast")
-  def test(): Boolean = {
-    testBoolean(true) &&
-      testInteger(5) &&
-      testIntegerNull(null) &&
-      testString("foo") &&
-      testStringNull(null) &&
-      testCharacter('A')
   }
 
   def testBoolean(x: Boolean): Boolean = {
@@ -39,11 +39,11 @@ object HijackedClassesUpcastTest {
 
   def testIntegerNull(x: Any): Boolean = {
     !x.isInstanceOf[Int] &&
-      !x.isInstanceOf[java.lang.Integer] &&
-      (x.asInstanceOf[Int] == 0) && {
-        val x2 = x.asInstanceOf[java.lang.Integer]
-        x2 == null
-      }
+    !x.isInstanceOf[java.lang.Integer] &&
+    (x.asInstanceOf[Int] == 0) && {
+      val x2 = x.asInstanceOf[java.lang.Integer]
+      x2 == null
+    }
   }
 
   def testString(x: String): Boolean = {
diff --git a/test-suite/src/main/scala/testsuite/core/InterfaceCall.scala b/test-suite/src/main/scala/testsuite/core/InterfaceCall.scala
index 609ae970..ffda1505 100644
--- a/test-suite/src/main/scala/testsuite/core/InterfaceCall.scala
+++ b/test-suite/src/main/scala/testsuite/core/InterfaceCall.scala
@@ -1,14 +1,11 @@
-package testsuite.core.interfacecall
+package testsuite.core
 
-import scala.scalajs.js.annotation._
+import testsuite.Assert.ok
 
 object InterfaceCall {
-  def main(): Unit = { val _ = test() }
-
-  @JSExportTopLevel("interfaceCall")
-  def test(): Boolean = {
+  def main(): Unit = {
     val c = new Concrete()
-    c.plus(c.zero, 1) == 1 && c.minus(1, c.zero) == 1
+    ok(c.plus(c.zero, 1) == 1 && c.minus(1, c.zero) == 1)
   }
 
   class Concrete extends AddSub with Zero {
diff --git a/test-suite/src/main/scala/testsuite/core/JSInteropTest.scala b/test-suite/src/main/scala/testsuite/core/JSInteropTest.scala
index 26754794..a4d3a5a8 100644
--- a/test-suite/src/main/scala/testsuite/core/JSInteropTest.scala
+++ b/test-suite/src/main/scala/testsuite/core/JSInteropTest.scala
@@ -1,55 +1,54 @@
-package testsuite.core.jsinterop
+package testsuite.core
 
 import scala.scalajs.js
-import scala.scalajs.js.annotation._
+import testsuite.Assert.ok
 
 object JSInteropTest {
-  def main(): Unit = { val _ = test() }
-
-  @JSExportTopLevel("jsInterop")
-  def test(): Boolean = {
-    testBasicTopLevel() &&
-      testBasicStatic() &&
-      testBasicInstance() &&
-      testArray() &&
-      testObject() &&
-      testOperators() &&
-      testLinkingInfo()
+  def main(): Unit = {
+    ok(
+      testBasicTopLevel() &&
+        testBasicStatic() &&
+        testBasicInstance() &&
+        testArray() &&
+        testObject() &&
+        testOperators() &&
+        testLinkingInfo()
+    )
   }
 
   def testBasicTopLevel(): Boolean = {
     ("" + js.undefined) == "undefined" &&
-      js.eval("3 + 4").asInstanceOf[Int] == 7 &&
-      js.isUndefined(())
+    js.eval("3 + 4").asInstanceOf[Int] == 7 &&
+    js.isUndefined(())
   }
 
   def testBasicStatic(): Boolean = {
     js.Math.PI == 3.1415926535897932 &&
-      js.Math.abs(-5.6) == 5.6 &&
-      js.Math.clz32(6548) == 19 &&
-      js.Math.min(5, 8, 2, 12, 3) == 2
+    js.Math.abs(-5.6) == 5.6 &&
+    js.Math.clz32(6548) == 19 &&
+    js.Math.min(5, 8, 2, 12, 3) == 2
   }
 
   def testBasicInstance(): Boolean = {
     val d = new js.Date(1710190169564.0)
     d.getTime() == 1710190169564.0 &&
-      d.getUTCFullYear() == 2024 && {
-        d.setTime(0.0)
-        d.getTime() == 0.0
-      }
+    d.getUTCFullYear() == 2024 && {
+      d.setTime(0.0)
+      d.getTime() == 0.0
+    }
   }
 
   def testArray(): Boolean = {
     val a = js.Array(1, 5, 3)
     a.length == 3 &&
-      a(0) == 1 &&
-      a(2) == 3 && {
-        a(0) = 65
-        a.push(78)
-        a.length == 4 &&
-          a(0) == 65 &&
-          a(3) == 78
-      }
+    a(0) == 1 &&
+    a(2) == 3 && {
+      a(0) = 65
+      a.push(78)
+      a.length == 4 &&
+      a(0) == 65 &&
+      a(3) == 78
+    }
   }
 
   def testObject(): Boolean = {
@@ -57,10 +56,10 @@ object JSInteropTest {
     js.isUndefined(o.foo) && {
       o.foo = 5
       o.hasOwnProperty("foo").asInstanceOf[Boolean] &&
-        o.foo.asInstanceOf[Int] == 5 && {
-          js.special.delete(o, "foo")
-          !o.hasOwnProperty("foo").asInstanceOf[Boolean]
-        }
+      o.foo.asInstanceOf[Int] == 5 && {
+        js.special.delete(o, "foo")
+        !o.hasOwnProperty("foo").asInstanceOf[Boolean]
+      }
     }
   }
 
@@ -68,35 +67,35 @@ object JSInteropTest {
     val x = 5.asInstanceOf[js.Dynamic]
     val y = 11.asInstanceOf[js.Dynamic]
     same(+x, 5) &&
-      same(-x, -5) &&
-      same(~x, -6) &&
-      same(!x, false) &&
-      same(js.typeOf(x), "number") && // regular typeof
-      same(js.typeOf(js.Dynamic.global.Date), "function") && // typeof global ref
-      same(x + y, 16) &&
-      same(x - y, -6) &&
-      same(x * y, 55) &&
-      same(x / y, 0.45454545454545453) &&
-      same(y % x, 1) &&
-      same(x << 3.asInstanceOf[js.Dynamic], 40) &&
-      same(x >> 1.asInstanceOf[js.Dynamic], 2) &&
-      same(x >>> 2.asInstanceOf[js.Dynamic], 1) &&
-      same(x & y, 1) &&
-      same(x | y, 15) &&
-      same(x ^ y, 14) &&
-      same(x < y, true) &&
-      same(x <= y, true) &&
-      same(x > y, false) &&
-      same(x >= y, false) &&
-      same(x && y, 11) &&
-      same(x || y, 5) &&
-      same(x ** 3.asInstanceOf[js.Dynamic], 125)
+    same(-x, -5) &&
+    same(~x, -6) &&
+    same(!x, false) &&
+    same(js.typeOf(x), "number") && // regular typeof
+    same(js.typeOf(js.Dynamic.global.Date), "function") && // typeof global ref
+    same(x + y, 16) &&
+    same(x - y, -6) &&
+    same(x * y, 55) &&
+    same(x / y, 0.45454545454545453) &&
+    same(y % x, 1) &&
+    same(x << 3.asInstanceOf[js.Dynamic], 40) &&
+    same(x >> 1.asInstanceOf[js.Dynamic], 2) &&
+    same(x >>> 2.asInstanceOf[js.Dynamic], 1) &&
+    same(x & y, 1) &&
+    same(x | y, 15) &&
+    same(x ^ y, 14) &&
+    same(x < y, true) &&
+    same(x <= y, true) &&
+    same(x > y, false) &&
+    same(x >= y, false) &&
+    same(x && y, 11) &&
+    same(x || y, 5) &&
+    same(x ** 3.asInstanceOf[js.Dynamic], 125)
   }
 
   def testLinkingInfo(): Boolean = {
     val linkingInfo = scala.scalajs.runtime.linkingInfo
     linkingInfo.esVersion >= 6 &&
-      linkingInfo.assumingES6 == true
+    linkingInfo.assumingES6 == true
   }
 
   def same(a: js.Any, b: js.Any): Boolean = js.special.strictEquals(a, b)
diff --git a/test-suite/src/main/scala/testsuite/core/Simple.scala b/test-suite/src/main/scala/testsuite/core/Simple.scala
index 5c46855e..1668bdc7 100644
--- a/test-suite/src/main/scala/testsuite/core/Simple.scala
+++ b/test-suite/src/main/scala/testsuite/core/Simple.scala
@@ -1,11 +1,9 @@
-package testsuite.core.simple
+package testsuite.core
 
-import scala.scalajs.js.annotation._
+import testsuite.Assert.ok
 
 object Simple {
-  def main(): Unit = { val _ = test() }
-  @JSExportTopLevel("simple")
-  def test(): Boolean = {
-    true
+  def main(): Unit = {
+    ok(true)
   }
 }
diff --git a/test-suite/src/main/scala/testsuite/core/ToStringTest.scala b/test-suite/src/main/scala/testsuite/core/ToStringTest.scala
index 434de3fb..90cefa99 100644
--- a/test-suite/src/main/scala/testsuite/core/ToStringTest.scala
+++ b/test-suite/src/main/scala/testsuite/core/ToStringTest.scala
@@ -1,45 +1,44 @@
-package testsuite.core.tostring
+package testsuite.core
 
-import scala.scalajs.js.annotation._
+import testsuite.Assert.ok
 
 object ToStringTest {
-  def main(): Unit = { val _ = test() }
-
-  @JSExportTopLevel("toStringConversions")
-  def test(): Boolean = {
-    testBoolean(true, "true") &&
-      testBoolean(false, "false") &&
-      !testBoolean(true, "tru") && // confidence test
-      testAny(true, "true") &&
-      testAny(false, "false") &&
-      testChar('A', "A") &&
-      testAny('A', "A") &&
-      testByte(54.toByte, "54") &&
-      testAny(54.toByte, "54") &&
-      testShort(6543.toShort, "6543") &&
-      testAny(6543.toShort, "6543") &&
-      testInt(-3423456, "-3423456") &&
-      testAny(-3423456, "-3423456") &&
-      testLong(1234567891011L, "1234567891011") &&
-      testAny(1234567891011L, "1234567891011") &&
-      testFloat(1.5f, "1.5") &&
-      testAny(1.5f, "1.5") &&
-      testDouble(1.4, "1.4") &&
-      testAny(1.4, "1.4") &&
-      testString("foo", "foo") &&
-      testAny("foo", "foo") &&
-      testString(null, "null") &&
-      testAny(null, "null") &&
-      testUndef((), "undefined") &&
-      testAny((), "undefined") &&
-      testMyToString(new MyToString(), "my toString") &&
-      testMyToString(null, "null") &&
-      testAny(new MyToString(), "my toString") &&
-      testToStringNull(new ToStringNull(), "null") &&
-      testToStringNull(null, "null") &&
-      testAny(new ToStringNull(), "null") &&
-      testConcat(1, "foo", "1foo") &&
-      testConcat(2, null, "2null")
+  def main(): Unit = {
+    ok(
+      testBoolean(true, "true") &&
+        testBoolean(false, "false") &&
+        !testBoolean(true, "tru") && // confidence test
+        testAny(true, "true") &&
+        testAny(false, "false") &&
+        testChar('A', "A") &&
+        testAny('A', "A") &&
+        testByte(54.toByte, "54") &&
+        testAny(54.toByte, "54") &&
+        testShort(6543.toShort, "6543") &&
+        testAny(6543.toShort, "6543") &&
+        testInt(-3423456, "-3423456") &&
+        testAny(-3423456, "-3423456") &&
+        testLong(1234567891011L, "1234567891011") &&
+        testAny(1234567891011L, "1234567891011") &&
+        testFloat(1.5f, "1.5") &&
+        testAny(1.5f, "1.5") &&
+        testDouble(1.4, "1.4") &&
+        testAny(1.4, "1.4") &&
+        testString("foo", "foo") &&
+        testAny("foo", "foo") &&
+        testString(null, "null") &&
+        testAny(null, "null") &&
+        testUndef((), "undefined") &&
+        testAny((), "undefined") &&
+        testMyToString(new MyToString(), "my toString") &&
+        testMyToString(null, "null") &&
+        testAny(new MyToString(), "my toString") &&
+        testToStringNull(new ToStringNull(), "null") &&
+        testToStringNull(null, "null") &&
+        testAny(new ToStringNull(), "null") &&
+        testConcat(1, "foo", "1foo") &&
+        testConcat(2, null, "2null")
+    )
   }
 
   def testBoolean(x: Boolean, expected: String): Boolean =
diff --git a/test-suite/src/main/scala/testsuite/core/VirtualDispatch.scala b/test-suite/src/main/scala/testsuite/core/VirtualDispatch.scala
index 9eecc100..47c90598 100644
--- a/test-suite/src/main/scala/testsuite/core/VirtualDispatch.scala
+++ b/test-suite/src/main/scala/testsuite/core/VirtualDispatch.scala
@@ -1,20 +1,19 @@
-package testsuite.core.virtualdispatch
+package testsuite.core
 
-import scala.scalajs.js.annotation._
+import testsuite.Assert.ok
 
 object VirtualDispatch {
-  def main(): Unit = { val _ = test() }
-
-  @JSExportTopLevel("virtualDispatch")
-  def test(): Boolean = {
+  def main(): Unit = {
     val a = new A
     val b = new B
 
-    testA(a) &&
-    testB(a, isInstanceOfA = true) &&
-    testB(b, isInstanceOfA = false) &&
-    testC(a, isInstanceOfA = true) &&
-    testC(b, isInstanceOfA = false)
+    ok(
+      testA(a) &&
+        testB(a, isInstanceOfA = true) &&
+        testB(b, isInstanceOfA = false) &&
+        testC(a, isInstanceOfA = true) &&
+        testC(b, isInstanceOfA = false)
+    )
   }
 
   def testA(a: A): Boolean = {
diff --git a/tests/src/test/scala/tests/CoreTests.scala b/tests/src/test/scala/tests/CoreTests.scala
index 0638f99e..fd4e8467 100644
--- a/tests/src/test/scala/tests/CoreTests.scala
+++ b/tests/src/test/scala/tests/CoreTests.scala
@@ -4,15 +4,22 @@ import scala.scalajs.js
 import scala.scalajs.js.annotation._
 import org.scalajs.macrotaskexecutor.MacrotaskExecutor.Implicits._
 
+/** The `tests/test` command compiles the Scala sources under `test-suite` into Wasm with static
+  * initializers (see `cli/src/main/scala/Main.scala`), where these static initializers should point
+  * to each main method in the classes of test-suites.
+  *
+  * These static initializers will be invoked from the start function in Wasm, which in turn will be
+  * invoked on instantiation of the Wasm module.
+  *
+  * Once we compile the test-suites into Wasm and put them under the `./target` directory,
+  * `tests/test` will instantiate those Wasm modules. If the test suites have an assertion failure,
+  * the Wasm module will execute `unreachable` and fail during instantiation.
+  */
 class CoreTests extends munit.FunSuite {
   cli.TestSuites.suites.map { suite =>
     test(suite.className) {
-      CoreTests.load(s"./target/${suite.className}.wasm").toFuture.map { exports =>
-        val testFunction =
-          exports
-            .selectDynamic(suite.methodName)
-            .asInstanceOf[js.Function0[Int]]
-        assert(testFunction() == 1)
+      CoreTests.load(s"./target/${suite.className}.wasm").toFuture.map { _ =>
+        ()
       }
     }
   }
diff --git a/wasm/src/main/scala/Compiler.scala b/wasm/src/main/scala/Compiler.scala
index 63c81b1b..df280a88 100644
--- a/wasm/src/main/scala/Compiler.scala
+++ b/wasm/src/main/scala/Compiler.scala
@@ -77,7 +77,7 @@ object Compiler {
         builder.transformTopLevelExport(tle)
       }
 
-      context.complete()
+      context.complete(moduleInitializers)
 
       val textOutput = new converters.WasmTextWriter().write(module)
       FS.writeFileSync(s"./target/$outputName.wat", textOutput.getBytes().toTypedArray)
diff --git a/wasm/src/main/scala/wasm4s/WasmContext.scala b/wasm/src/main/scala/wasm4s/WasmContext.scala
index b4350c91..4fa24f94 100644
--- a/wasm/src/main/scala/wasm4s/WasmContext.scala
+++ b/wasm/src/main/scala/wasm4s/WasmContext.scala
@@ -14,6 +14,9 @@ import org.scalajs.ir.ClassKind
 import scala.collection.mutable.LinkedHashMap
 import wasm.ir2wasm.TypeTransformer
 
+import org.scalajs.linker.interface.ModuleInitializer
+import org.scalajs.linker.interface.unstable.ModuleInitializerImpl
+
 trait ReadOnlyWasmContext {
   import WasmContext._
   protected val gcTypes = new WasmSymbolTable[WasmTypeName, WasmGCTypeDefinition]()
@@ -173,7 +176,11 @@ class WasmContext(val module: WasmModule) extends FunctionTypeWriterWasmContext
   def putClassInfo(name: IRNames.ClassName, info: WasmClassInfo): Unit =
     classInfo.put(name, info)
 
-  private def addHelperImport(name: WasmFunctionName, params: List[WasmType], results: List[WasmType]): Unit = {
+  private def addHelperImport(
+      name: WasmFunctionName,
+      params: List[WasmType],
+      results: List[WasmType]
+  ): Unit = {
     val sig = WasmFunctionSignature(params, results)
     val typ = WasmFunctionType(addFunctionType(sig), sig)
     module.addImport(WasmImport(name.className, name.methodName, WasmImportDesc.Func(name, typ)))
@@ -208,7 +215,11 @@ class WasmContext(val module: WasmModule) extends FunctionTypeWriterWasmContext
   addHelperImport(WasmFunctionName.intToString, List(WasmInt32), List(WasmRefType.any))
   addHelperImport(WasmFunctionName.longToString, List(WasmInt64), List(WasmRefType.any))
   addHelperImport(WasmFunctionName.doubleToString, List(WasmFloat64), List(WasmRefType.any))
-  addHelperImport(WasmFunctionName.stringConcat, List(WasmRefType.any, WasmRefType.any), List(WasmRefType.any))
+  addHelperImport(
+    WasmFunctionName.stringConcat,
+    List(WasmRefType.any, WasmRefType.any),
+    List(WasmRefType.any)
+  )
   addHelperImport(WasmFunctionName.isString, List(WasmAnyRef), List(WasmInt32))
 
   addHelperImport(WasmFunctionName.jsValueHashCode, List(WasmRefType.any), List(WasmInt32))
@@ -218,14 +229,26 @@ class WasmContext(val module: WasmModule) extends FunctionTypeWriterWasmContext
   addHelperImport(WasmFunctionName.jsGlobalRefTypeof, List(WasmRefType.any), List(WasmRefType.any))
   addHelperImport(WasmFunctionName.jsNewArray, Nil, List(WasmAnyRef))
   addHelperImport(WasmFunctionName.jsArrayPush, List(WasmAnyRef, WasmAnyRef), List(WasmAnyRef))
-  addHelperImport(WasmFunctionName.jsArraySpreadPush, List(WasmAnyRef, WasmAnyRef), List(WasmAnyRef))
+  addHelperImport(
+    WasmFunctionName.jsArraySpreadPush,
+    List(WasmAnyRef, WasmAnyRef),
+    List(WasmAnyRef)
+  )
   addHelperImport(WasmFunctionName.jsNewObject, Nil, List(WasmAnyRef))
-  addHelperImport(WasmFunctionName.jsObjectPush, List(WasmAnyRef, WasmAnyRef, WasmAnyRef), List(WasmAnyRef))
+  addHelperImport(
+    WasmFunctionName.jsObjectPush,
+    List(WasmAnyRef, WasmAnyRef, WasmAnyRef),
+    List(WasmAnyRef)
+  )
   addHelperImport(WasmFunctionName.jsSelect, List(WasmAnyRef, WasmAnyRef), List(WasmAnyRef))
   addHelperImport(WasmFunctionName.jsSelectSet, List(WasmAnyRef, WasmAnyRef, WasmAnyRef), Nil)
   addHelperImport(WasmFunctionName.jsNew, List(WasmAnyRef, WasmAnyRef), List(WasmAnyRef))
   addHelperImport(WasmFunctionName.jsFunctionApply, List(WasmAnyRef, WasmAnyRef), List(WasmAnyRef))
-  addHelperImport(WasmFunctionName.jsMethodApply, List(WasmAnyRef, WasmAnyRef, WasmAnyRef), List(WasmAnyRef))
+  addHelperImport(
+    WasmFunctionName.jsMethodApply,
+    List(WasmAnyRef, WasmAnyRef, WasmAnyRef),
+    List(WasmAnyRef)
+  )
   addHelperImport(WasmFunctionName.jsDelete, List(WasmAnyRef, WasmAnyRef), Nil)
   addHelperImport(WasmFunctionName.jsIsTruthy, List(WasmAnyRef), List(WasmInt32))
   addHelperImport(WasmFunctionName.jsLinkingInfo, Nil, List(WasmAnyRef))
@@ -243,7 +266,7 @@ class WasmContext(val module: WasmModule) extends FunctionTypeWriterWasmContext
   def addStartInstructions(instrs: List[WasmInstr]): Unit =
     _startInstructions ++= instrs
 
-  def complete(): Unit = {
+  def complete(moduleInitializers: List[ModuleInitializer]): Unit = {
     val instrs = _startInstructions
 
     for ((str, globalName) <- constantStringGlobals) {
@@ -255,6 +278,21 @@ class WasmContext(val module: WasmModule) extends FunctionTypeWriterWasmContext
       }
       instrs += WasmInstr.GLOBAL_SET(WasmImmediate.GlobalIdx(globalName))
     }
+    moduleInitializers.foreach { init =>
+      ModuleInitializerImpl.fromInitializer(init.initializer) match {
+        case ModuleInitializerImpl.MainMethodWithArgs(className, encodedMainMethodName, args) =>
+          () // TODO: but we don't use args yet in scala-wasm
+        case ModuleInitializerImpl.VoidMainMethod(className, encodedMainMethodName) =>
+          val name = className.withSuffix("$")
+          instrs +=
+            WasmInstr.CALL(WasmImmediate.FuncIdx(Names.WasmFunctionName.loadModule(name)))
+          instrs += WasmInstr.REF_AS_NOT_NULL
+          instrs +=
+            WasmInstr.CALL(
+              WasmImmediate.FuncIdx(WasmFunctionName(name, encodedMainMethodName))
+            )
+      }
+    }
 
     if (_startInstructions.nonEmpty) {
       val sig = WasmFunctionSignature(Nil, Nil)
@@ -381,7 +419,8 @@ object WasmContext {
         .getOrElse(throw new Error(s"Function not found: $name"))
     def resolveWithIdx(name: WasmFunctionName): (Int, WasmFunctionInfo) = {
       val idx = functions.indexWhere(_.name.methodName == name.methodName)
-      if (idx < 0) throw new Error(s"Function not found: $name among ${functions.map(_.name.methodName)}")
+      if (idx < 0)
+        throw new Error(s"Function not found: $name among ${functions.map(_.name.methodName)}")
       else (idx, functions(idx))
     }
   }