e2e test running Jest programmatically

Author: jeysal

e2e/__tests__/runProgramatically.test.js

@@ -0,0 +1,19 @@
+/**
+ * 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.
+ *
+ * @flow
+ */
+
+import {resolve} from 'path';
+
+import {run} from '../Utils';
+
+const dir = resolve(__dirname, '..', 'run-programatically');
+
+test('run Jest programatically', () => {
+  const {stdout} = run(`node index.js --version`, dir);
+  expect(stdout).toMatch(/\d{2}\.\d{1,2}\.\d{1,2}[\-\S]*-dev$/);
+});

e2e/run-programatically/index.js

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+#!/usr/bin/env node
+/**
+ * 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.
+ *
+ * @flow
+ */
+
+// Running Jest like this is not officially supported,
+// but it is common practice until there is a proper API as a substitute.
+require('jest').run(process.argv);