Testing: Trigger E2E test failure on console logging

test/e2e/specs/change-detection.test.js

@@ -196,6 +196,8 @@ describe( 'Change detection', () => {
 		await page.setOfflineMode( false );
 
 		await assertIsDirty( true );
+
+		expect( console ).toHaveErroredWith( 'Failed to load resource: net::ERR_INTERNET_DISCONNECTED' );
 	} );
 
 	it( 'Should prompt if changes and save is in-flight', async () => {

test/e2e/support/setup-test-framework.js

@@ -3,12 +3,16 @@
  */
 import 'expect-puppeteer';
 
+/**
+ * WordPress dependencies
+ */
+import '@wordpress/jest-console';
+
 /**
  * Internal dependencies
  */
 import {
 	clearLocalStorage,
-	disablePageDialogAccept,
 	enablePageDialogAccept,
 	setViewport,
 	visitAdmin,
@@ -19,6 +23,26 @@ import {
  */
 const { PUPPETEER_TIMEOUT } = process.env;
 
+/**
+ * Set of console logging types observed to protect against unexpected yet
+ * handled (i.e. not catastrophic) errors or warnings. Each key corresponds
+ * to the Puppeteer ConsoleMessage type, its value the corresponding function
+ * on the console global object.
+ *
+ * @type {Object<string,string>}
+ */
+const OBSERVED_CONSOLE_MESSAGE_TYPES = {
+	warning: 'warn',
+	error: 'error',
+};
+
+/**
+ * Array of page event tuples of [ eventName, handler ].
+ *
+ * @type {Array}
+ */
+const pageEvents = [];
+
 // The Jest timeout is increased because these tests are a bit slow
 jest.setTimeout( PUPPETEER_TIMEOUT || 100000 );
 
@@ -27,29 +51,92 @@ async function setupBrowser() {
 	await setViewport( 'large' );
 }
 
-// Before every test suite run, delete all content created by the test. This ensures
-// other posts/comments/etc. aren't dirtying tests and tests don't depend on
-// each other's side-effects.
-beforeAll( async () => {
-	enablePageDialogAccept();
-
+/**
+ * Navigates to the post listing screen and bulk-trashes any posts which exist.
+ *
+ * @return {Promise} Promise resolving once posts have been trashed.
+ */
+async function trashExistingPosts() {
 	// Visit `/wp-admin/edit.php` so we can see a list of posts and delete them.
 	await visitAdmin( 'edit.php' );
 
 	// If this selector doesn't exist there are no posts for us to delete.
 	const bulkSelector = await page.$( '#bulk-action-selector-top' );
-	if ( bulkSelector ) {
-		// Select all posts.
-		await page.waitForSelector( '#cb-select-all-1' );
-		await page.click( '#cb-select-all-1' );
-		// Select the "bulk actions" > "trash" option.
-		await page.select( '#bulk-action-selector-top', 'trash' );
-		// Submit the form to send all draft/scheduled/published posts to the trash.
-		await page.click( '#doaction' );
-		await page.waitForXPath(
-			'//*[contains(@class, "updated notice")]/p[contains(text(), "moved to the Trash.")]'
-		);
+	if ( ! bulkSelector ) {
+		return;
 	}
+
+	// Select all posts.
+	await page.waitForSelector( '#cb-select-all-1' );
+	await page.click( '#cb-select-all-1' );
+	// Select the "bulk actions" > "trash" option.
+	await page.select( '#bulk-action-selector-top', 'trash' );
+	// Submit the form to send all draft/scheduled/published posts to the trash.
+	await page.click( '#doaction' );
+	return page.waitForXPath(
+		'//*[contains(@class, "updated notice")]/p[contains(text(), "moved to the Trash.")]'
+	);
+}
+
+/**
+ * Adds an event listener to the page to handle additions of page event
+ * handlers, to assure that they are removed at test teardown.
+ */
+function capturePageEventsForTearDown() {
+	page.on( 'newListener', ( eventName, listener ) => {
+		pageEvents.push( [ eventName, listener ] );
+	} );
+}
+
+/**
+ * Removes all bound page event handlers.
+ */
+function removePageEvents() {
+	pageEvents.forEach( ( [ eventName, handler ] ) => {
+		page.removeListener( eventName, handler );
+	} );
+}
+
+/**
+ * Adds a page event handler to emit uncaught exception to process if one of
+ * the observed console logging types is encountered.
+ */
+function observeConsoleLogging() {
+	page.on( 'console', ( message ) => {
+		const type = message.type();
+		if ( ! OBSERVED_CONSOLE_MESSAGE_TYPES.hasOwnProperty( type ) ) {
+			return;
+		}
+
+		const text = message.text();
+
+		// An exception is made for _blanket_ deprecation warnings: Those
+		// which log regardless of whether a deprecated feature is in use.
+		if ( text.includes( 'This is a global warning' ) ) {
+			return;
+		}
+
+		const logFunction = OBSERVED_CONSOLE_MESSAGE_TYPES[ type ];
+
+		// Disable reason: We intentionally bubble up the console message
+		// which, unless the test explicitly anticipates the logging via
+		// @wordpress/jest-console matchers, will cause the intended test
+		// failure.
+
+		// eslint-disable-next-line no-console
+		console[ logFunction ]( text );
+	} );
+}
+
+// Before every test suite run, delete all content created by the test. This ensures
+// other posts/comments/etc. aren't dirtying tests and tests don't depend on
+// each other's side-effects.
+beforeAll( async () => {
+	capturePageEventsForTearDown();
+	enablePageDialogAccept();
+	observeConsoleLogging();
+
+	await trashExistingPosts();
 	await setupBrowser();
 } );
 
@@ -58,5 +145,5 @@ afterEach( async () => {
 } );
 
 afterAll( () => {
-	disablePageDialogAccept();
+	removePageEvents();
 } );

test/e2e/support/utils.js

@@ -307,11 +307,3 @@ async function acceptPageDialog( dialog ) {
 export function enablePageDialogAccept() {
 	page.on( 'dialog', acceptPageDialog );
 }
-
-/**
- * Disables even listener which accepts a page dialog which
- * may appear when navigating away from Gutenberg.
- */
-export function disablePageDialogAccept() {
-	page.removeListener( 'dialog', acceptPageDialog );
-}