Core: Error when a module callback has a promise as a return value

Ref qunitjs#1600.

src/module.js

@@ -86,9 +86,8 @@ function processModule( name, options, executeNow, modifiers = {} ) {
 
 		const cbReturnValue = executeNow.call( module.testEnvironment, moduleFns );
 		if ( cbReturnValue != null && objectType( cbReturnValue.then ) === "function" ) {
-			Logger.warn( "Returning a promise from a module callback is not supported. " +
-				"Instead, use hooks for async behavior. " +
-				"This will become an error in QUnit 3.0." );
+			throw new Error( "Returning a promise from a module callback is not supported. " +
+				"Instead, use hooks for async behavior." );
 		}
 
 		moduleStack.pop();

test/cli/fixtures/async-module-warning/promise-test.js

@@ -1,6 +1,18 @@
-QUnit.module( "module manually returning a promise", function() {
-	QUnit.test( "has a test", function( assert ) {
-		assert.true( true );
+var errorFromModule;
+try {
+	QUnit.module( "module manually returning a promise", function() {
+		QUnit.test( "has a test", function( assert ) {
+			assert.true( true );
+		} );
+		return Promise.resolve( 1 );
 	} );
-	return Promise.resolve( 1 );
+} catch ( e ) {
+	errorFromModule = e;
+}
+
+QUnit.test( "Correct error thrown from module function that returns a promise", function( assert ) {
+	assert.true( errorFromModule instanceof Error );
+	assert.strictEqual( errorFromModule.message,
+		"Returning a promise from a module callback is not supported. " +
+		"Instead, use hooks for async behavior.", "Error has correct message" );
 } );

test/cli/fixtures/async-module-warning/test.js

@@ -1,10 +1,18 @@
-// eslint-disable-next-line qunit/no-async-module-callbacks
-QUnit.module( "module with async callback", async function() {
-	await Promise.resolve( 1 );
-
-	QUnit.test( "has a test", function( assert ) {
-		assert.true( true );
+var errorFromAsyncModule;
+try {
+	/* eslint-disable-next-line qunit/no-async-module-callbacks */
+	QUnit.module( "async module function", async function() {
+		QUnit.test( "has a test", function( assert ) {
+			assert.true( true );
+		} );
 	} );
-} );
+} catch ( e ) {
+	errorFromAsyncModule = e;
+}
 
-QUnit.module( "resulting parent module" );
+QUnit.test( "Correct error thrown from async module function", function( assert ) {
+	assert.true( errorFromAsyncModule instanceof Error );
+	assert.strictEqual( errorFromAsyncModule.message,
+		"Returning a promise from a module callback is not supported. " +
+		"Instead, use hooks for async behavior.", "Error has correct message" );
+} );

test/cli/fixtures/expected/tap-outputs.js

@@ -343,18 +343,20 @@ ok 1 module providing hooks > module not providing hooks > has a test
 
 	"qunit async-module-warning/test.js":
 `TAP version 13
-ok 1 resulting parent module > has a test
-1..1
-# pass 1
+ok 1 async module function > has a test
+ok 2 async module function > Correct error thrown from async module function
+1..2
+# pass 2
 # skip 0
 # todo 0
 # fail 0`,
 
 	"qunit async-module-warning/promise-test.js":
 `TAP version 13
 ok 1 module manually returning a promise > has a test
-1..1
-# pass 1
+ok 2 module manually returning a promise > Correct error thrown from module function that returns a promise
+1..2
+# pass 2
 # skip 0
 # todo 0
 # fail 0`,

test/cli/main.js

@@ -498,21 +498,21 @@ QUnit.module( "CLI Main", () => {
 		assert.equal( execution.stdout, expectedOutput[ command ] );
 	} );
 
-	QUnit.test( "warns about unsupported async module callback", async assert => {
+	QUnit.test( "errors on async module callback", async assert => {
 		const command = "qunit async-module-warning/test.js";
 		const execution = await execute( command );
 
 		assert.equal( execution.code, 0 );
-		assert.equal( execution.stderr, "Returning a promise from a module callback is not supported. Instead, use hooks for async behavior. This will become an error in QUnit 3.0.", "The warning shows" );
+		assert.equal( execution.stderr, "" );
 		assert.equal( execution.stdout, expectedOutput[ command ] );
 	} );
 
-	QUnit.test( "warns about unsupported promise return value from module", async assert => {
+	QUnit.test( "errors on promise return value from module", async assert => {
 		const command = "qunit async-module-warning/promise-test.js";
 		const execution = await execute( command );
 
 		assert.equal( execution.code, 0 );
-		assert.equal( execution.stderr, "Returning a promise from a module callback is not supported. Instead, use hooks for async behavior. This will become an error in QUnit 3.0.", "The warning shows" );
+		assert.equal( execution.stderr, "" );
 		assert.equal( execution.stdout, expectedOutput[ command ] );
 	} );