Tests: Adds reporter that shows JS test errors on GitHub when executing GitHub workflows

test/unit/GithubActionsReporter.js

@@ -0,0 +1,53 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+const newLine = /\n/g;
+const encodedNewLine = '%0A';
+const lineAndColumnInStackTrace = /^.*?:([0-9]+):([0-9]+).*$/;
+
+class GithubActionReporter {
+	async onRunComplete( _contexts, _aggregatedResults ) {
+		if ( ! _aggregatedResults ) {
+			return;
+		}
+		const messages = getMessages( _aggregatedResults.testResults );
+
+		for ( const message of messages ) {
+			// eslint-disable-next-line no-console
+			console.log( message );
+		}
+	}
+}
+
+function getMessages( results ) {
+	if ( ! results ) return [];
+
+	return results.reduce(
+		flatMap( ( { testFilePath, testResults } ) =>
+			testResults
+				.filter( ( r ) => r.status === 'failed' )
+				.reduce(
+					flatMap( ( r ) => r.failureMessages ),
+					[]
+				)
+				.map( ( m ) => m.replace( newLine, encodedNewLine ) )
+				.map( ( m ) => lineAndColumnInStackTrace.exec( m ) )
+				//.filter((m): m is RegExpExecArray => m !== null)
+				.map(
+					( [ message, line, col ] ) =>
+						`::error file=${ testFilePath },line=${ line },col=${ col }::${ message }`
+				)
+		),
+		[]
+	);
+}
+
+function flatMap( fn ) {
+	return ( out, entry ) => out.concat( ...fn( entry ) );
+}
+
+module.exports = GithubActionReporter;

test/unit/jest.config.js

@@ -43,4 +43,5 @@ module.exports = {
 		'jest-watch-typeahead/filename',
 		'jest-watch-typeahead/testname',
 	],
+	reporters: [ 'default', '<rootDir>/test/unit/GithubActionsReporter.js' ],
 };

test/unit/test/index.test.js

@@ -0,0 +1,5 @@
+describe( 'My test', () => {
+	test( 'A equals B', () => {
+		expect( 'a' ).toBe( 'b' );
+	} );
+} );