[engineering] ensure typescript integration tests emit junit reports

not sure if this was intentional but it seems like an oversight

extensions/typescript-language-features/src/test/unit/index.ts

@@ -15,14 +15,28 @@
 // to report the results back to the caller. When the tests are finished, return
 // a possible error to the callback or null if none.
 
+const path = require('path');
 const testRunner = require('../../../../../test/integration/electron/testrunner');
 
-// You can directly control Mocha options by uncommenting the following lines
-// See https://github.com/mochajs/mocha/wiki/Using-mocha-programmatically#set-options for more info
-testRunner.configure({
-	ui: 'tdd', 		// the TDD UI is being used in extension.test.ts (suite, test, etc.)
+const suite = 'Integration TypeScript Tests';
+
+const options: import('mocha').MochaOptions = {
+	ui: 'tdd',
 	color: true,
-	timeout: 60000,
-});
+	timeout: 60000
+};
+
+if (process.env.BUILD_ARTIFACTSTAGINGDIRECTORY) {
+	options.reporter = 'mocha-multi-reporters';
+	options.reporterOptions = {
+		reporterEnabled: 'spec, mocha-junit-reporter',
+		mochaJunitReporterReporterOptions: {
+			testsuitesTitle: `${suite} ${process.platform}`,
+			mochaFile: path.join(process.env.BUILD_ARTIFACTSTAGINGDIRECTORY, `test-results/${process.platform}-${process.arch}-${suite.toLowerCase().replace(/[^\w]/g, '-')}-results.xml`)
+		}
+	};
+}
+
+testRunner.configure(options);
 
 export = testRunner;