add test case for ordering to list-tests e2e test

Author: jeysal

e2e/__tests__/__snapshots__/list_tests.test.js.snap

@@ -2,7 +2,8 @@
 
 exports[`--listTests flag causes tests to be printed in different lines 1`] = `
 "/MOCK_ABOLUTE_PATH/e2e/list-tests/__tests__/dummy.test.js
-/MOCK_ABOLUTE_PATH/e2e/list-tests/__tests__/other.test.js"
+/MOCK_ABOLUTE_PATH/e2e/list-tests/__tests__/other.test.js
+/MOCK_ABOLUTE_PATH/e2e/list-tests/__tests__/with-dep.test.js"
 `;
 
-exports[`--listTests flag causes tests to be printed out as JSON when using the --json flag 1`] = `"[\\"/MOCK_ABOLUTE_PATH/e2e/list-tests/__tests__/dummy.test.js\\",\\"/MOCK_ABOLUTE_PATH/e2e/list-tests/__tests__/other.test.js\\"]"`;
+exports[`--listTests flag causes tests to be printed out as JSON when using the --json flag 1`] = `"[\\"/MOCK_ABOLUTE_PATH/e2e/list-tests/__tests__/dummy.test.js\\",\\"/MOCK_ABOLUTE_PATH/e2e/list-tests/__tests__/other.test.js\\",\\"/MOCK_ABOLUTE_PATH/e2e/list-tests/__tests__/with-dep.test.js\\"]"`;

e2e/__tests__/list_tests.test.js

@@ -33,6 +33,16 @@ describe('--listTests flag', () => {
     ).toMatchSnapshot();
   });
 
+  it('prints tests in the execution order determined by their dependency sizes', () => {
+    const {status, stdout} = runJest('list-tests', ['--listTests']);
+    expect(status).toBe(0);
+    expect(normalizePaths(stdout).split('\n')).toEqual([
+      expect.stringContaining('/with-dep.test.js'),
+      expect.stringContaining('/other.test.js'),
+      expect.stringContaining('/dummy.test.js'),
+    ]);
+  });
+
   it('causes tests to be printed out as JSON when using the --json flag', () => {
     const {status, stdout} = runJest('list-tests', ['--listTests', '--json']);
 

e2e/list-tests/__tests__/other.test.js

@@ -11,3 +11,6 @@ it("isn't actually run", () => {
   // (because it is only used for --listTests)
   expect(true).toBe(false);
 });
+
+// Because of this comment, other.test.js is slightly larger than dummy.test.js.
+// This matters for the order in which tests are sequenced.

e2e/list-tests/__tests__/with-dep.test.js

@@ -0,0 +1,15 @@
+/**
+ * Copyright (c) 2018-present, Facebook, Inc. 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.
+ */
+
+'use strict';
+
+require('./dummy.test.js');
+
+it("isn't actually run", () => {
+  // (because it is only used for --listTests)
+  expect(true).toBe(false);
+});