diff --git a/compiler/testData/codegen/box/assert/alwaysEnable.kt b/compiler/testData/codegen/box/assert/alwaysEnable.kt
index 076ae6d12bf..c33cc157e43 100644
--- a/compiler/testData/codegen/box/assert/alwaysEnable.kt
+++ b/compiler/testData/codegen/box/assert/alwaysEnable.kt
@@ -1,5 +1,3 @@
-// IGNORE_BACKEND: WASM
-// WASM_MUTE_REASON: STDLIB_ASSERT
 // IGNORE_BACKEND: JS_IR
 // IGNORE_BACKEND: JS_IR_ES6
 // IGNORE_BACKEND: JS
diff --git a/compiler/testData/codegen/box/casts/functions/asFunKBig.kt b/compiler/testData/codegen/box/casts/functions/asFunKBig.kt
index b9b74d8bc6a..857b6c39825 100644
--- a/compiler/testData/codegen/box/casts/functions/asFunKBig.kt
+++ b/compiler/testData/codegen/box/casts/functions/asFunKBig.kt
@@ -1,5 +1,5 @@
 // IGNORE_BACKEND: WASM
-// WASM_MUTE_REASON: KOTLIN_TEST_LIB
+// WASM_MUTE_REASON: CLASS_REFERENCES
 // IGNORE_BACKEND: JS_IR
 // IGNORE_BACKEND: JS_IR_ES6
 // TODO: muted automatically, investigate should it be ran for JS or not
diff --git a/compiler/testData/codegen/box/casts/functions/isFunKBig.kt b/compiler/testData/codegen/box/casts/functions/isFunKBig.kt
index 8e144added4..821e78fb38c 100644
--- a/compiler/testData/codegen/box/casts/functions/isFunKBig.kt
+++ b/compiler/testData/codegen/box/casts/functions/isFunKBig.kt
@@ -1,5 +1,3 @@
-// IGNORE_BACKEND: WASM
-// WASM_MUTE_REASON: IGNORED_IN_JS
 // IGNORE_BACKEND: JS_IR
 // IGNORE_BACKEND: JS_IR_ES6
 // TODO: muted automatically, investigate should it be ran for JS or not
diff --git a/compiler/testData/codegen/box/casts/functions/reifiedAsFunKBig.kt b/compiler/testData/codegen/box/casts/functions/reifiedAsFunKBig.kt
index fe47ae62f7f..5820c0e753f 100644
--- a/compiler/testData/codegen/box/casts/functions/reifiedAsFunKBig.kt
+++ b/compiler/testData/codegen/box/casts/functions/reifiedAsFunKBig.kt
@@ -1,5 +1,5 @@
 // IGNORE_BACKEND: WASM
-// WASM_MUTE_REASON: KOTLIN_TEST_LIB
+// WASM_MUTE_REASON: CLASS_REFERENCES
 // IGNORE_BACKEND: JS_IR
 // IGNORE_BACKEND: JS_IR_ES6
 // TODO: muted automatically, investigate should it be ran for JS or not
diff --git a/compiler/testData/codegen/box/casts/functions/reifiedIsFunKBig.kt b/compiler/testData/codegen/box/casts/functions/reifiedIsFunKBig.kt
index e71fc2846b9..f91b9746982 100644
--- a/compiler/testData/codegen/box/casts/functions/reifiedIsFunKBig.kt
+++ b/compiler/testData/codegen/box/casts/functions/reifiedIsFunKBig.kt
@@ -1,5 +1,3 @@
-// IGNORE_BACKEND: WASM
-// WASM_MUTE_REASON: IGNORED_IN_JS
 // IGNORE_BACKEND: JS_IR
 // IGNORE_BACKEND: JS_IR_ES6
 // TODO: muted automatically, investigate should it be ran for JS or not
diff --git a/compiler/testData/codegen/box/casts/functions/reifiedIsFunKSmall.kt b/compiler/testData/codegen/box/casts/functions/reifiedIsFunKSmall.kt
index a8c328c2fd2..9225f9021c2 100644
--- a/compiler/testData/codegen/box/casts/functions/reifiedIsFunKSmall.kt
+++ b/compiler/testData/codegen/box/casts/functions/reifiedIsFunKSmall.kt
@@ -1,5 +1,3 @@
-// IGNORE_BACKEND: WASM
-// WASM_MUTE_REASON: IGNORED_IN_JS
 // IGNORE_BACKEND: JS_IR
 // IGNORE_BACKEND: JS_IR_ES6
 // TODO: muted automatically, investigate should it be ran for JS or not
diff --git a/compiler/testData/codegen/box/constants/comparisonTrue.kt b/compiler/testData/codegen/box/constants/comparisonTrue.kt
index daca2bae7c9..86603391ab9 100644
--- a/compiler/testData/codegen/box/constants/comparisonTrue.kt
+++ b/compiler/testData/codegen/box/constants/comparisonTrue.kt
@@ -1,3 +1,6 @@
+// IGNORE_BACKEND: WASM
+// WASM_MUTE_REASON: FLAKY
+
 // WITH_RUNTIME
 fun foo(): Array<Boolean> {
     return arrayOf(
diff --git a/libraries/stdlib/wasm/src/kotlin/Assertions.kt b/libraries/stdlib/wasm/src/kotlin/Assertions.kt
new file mode 100644
index 00000000000..fca88b71234
--- /dev/null
+++ b/libraries/stdlib/wasm/src/kotlin/Assertions.kt
@@ -0,0 +1,27 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package kotlin
+
+// TODO: Make this dependant on the compiler flag (like -ea on JVM)
+
+/**
+ * Throws an [AssertionError] if the [value] is false.
+ */
+@kotlin.internal.InlineOnly
+public inline fun assert(value: Boolean) {
+    assert(value) { "Assertion failed" }
+}
+
+/**
+ * Throws an [AssertionError] calculated by [lazyMessage] if the [value] is false.
+ */
+@kotlin.internal.InlineOnly
+public inline fun assert(value: Boolean, lazyMessage: () -> Any) {
+    if (!value) {
+        val message = lazyMessage()
+        throw AssertionError(message)
+    }
+}
diff --git a/libraries/stdlib/wasm/stubs/testHelpers.kt b/libraries/stdlib/wasm/stubs/testHelpers.kt
index 70128e11706..0abb0b3909e 100644
--- a/libraries/stdlib/wasm/stubs/testHelpers.kt
+++ b/libraries/stdlib/wasm/stubs/testHelpers.kt
@@ -8,20 +8,7 @@ package kotlin.test
 import kotlin.internal.InlineOnly
 import kotlin.internal.OnlyInputTypes
 
-public fun assert(x: Boolean) {
-    if (!x) throw AssertionError("Assertion failed")
-}
-
-/** Asserts that the [expected] value is equal to the [actual] value, with an optional [message]. */
-public fun <@OnlyInputTypes T> assertEquals(expected: T, actual: T, message: String? = null) {
-    if (expected != actual) throw AssertionError("assertEquals failed: expected:$expected, actual:$actual, message=$message")
-}
-
-/** Asserts that the [actual] value is not equal to the illegal value, with an optional [message]. */
-public fun <@OnlyInputTypes T> assertNotEquals(illegal: T, actual: T, message: String? = null) {
-    if (illegal == actual) throw AssertionError("assertNotEquals failed: illegal:$illegal, actual:$actual, message=$message")
-}
-
+// TODO: Remove this once we support CLASS_REFERENCE IR node
 @InlineOnly
 public inline fun <reified T : Throwable> assertFailsWith(message: String? = null, block: () -> Unit): T {
     var throwable: Throwable? = null
@@ -32,5 +19,3 @@ public inline fun <reified T : Throwable> assertFailsWith(message: String? = nul
     }
     return throwable as? T ?: throw AssertionError("assertFailsWith failed: $message")
 }
-
-public fun assertTrue(x: Boolean) = assert(x)
diff --git a/libraries/stdlib/wasm/stubs/testHelpers2.kt b/libraries/stdlib/wasm/stubs/testHelpers2.kt
deleted file mode 100644
index bae3a0dbeb9..00000000000
--- a/libraries/stdlib/wasm/stubs/testHelpers2.kt
+++ /dev/null
@@ -1,17 +0,0 @@
-/*
- * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
- * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
- */
-
-package kotlin
-
-import kotlin.internal.OnlyInputTypes
-
-public fun assert(x: Boolean) {
-    if (!x) throw AssertionError("Assertion failed")
-}
-
-/** Asserts that the [expected] value is equal to the [actual] value, with an optional [message]. */
-public fun <@OnlyInputTypes T> assertEquals(expected: T, actual: T, message: String? = null) {
-    if (expected != actual) throw AssertionError("assertEquals failed: expected:$expected, actual:$actual, message=$message")
-}
\ No newline at end of file