Reallowed single string arguments for pending tests

- Continues to validate arguments to avoid accidental skips from jestjs#5558

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

@@ -186,3 +186,36 @@ Snapshots:   0 total
 Time:        <<REPLACED>>
 Ran all test suites."
 `;
+
+exports[`tests with no implementation 1`] = `
+"PASS __tests__/only-constructs.test.js
+  ✓ it
+  ○ skipped 2 tests
+
+"
+`;
+
+exports[`tests with no implementation 2`] = `
+"Test Suites: 1 passed, 1 total
+Tests:       2 skipped, 1 passed, 3 total
+Snapshots:   0 total
+Time:        <<REPLACED>>
+Ran all test suites."
+`;
+
+exports[`tests with no implementation with expand arg 1`] = `
+"PASS __tests__/only-constructs.test.js
+  ✓ it
+  ○ it, no implementation
+  ○ test, no implementation
+
+"
+`;
+
+exports[`tests with no implementation with expand arg 2`] = `
+"Test Suites: 1 passed, 1 total
+Tests:       2 skipped, 1 passed, 3 total
+Snapshots:   0 total
+Time:        <<REPLACED>>
+Ran all test suites."
+`;

e2e/__tests__/globals.test.js

@@ -112,7 +112,7 @@ test('only', () => {
   expect(summary).toMatchSnapshot();
 });
 
-test('cannot test with no implementation', () => {
+test('tests with no implementation', () => {
   const filename = 'only-constructs.test.js';
   const content = `
     it('it', () => {});
@@ -122,7 +122,7 @@ test('cannot test with no implementation', () => {
 
   writeFiles(TEST_DIR, {[filename]: content});
   const {stderr, status} = runJest(DIR);
-  expect(status).toBe(1);
+  expect(status).toBe(0);
 
   const {summary} = extractSummary(stderr);
   expect(cleanStderr(stderr)).toMatchSnapshot();
@@ -190,7 +190,7 @@ test('only with expand arg', () => {
   expect(summary).toMatchSnapshot();
 });
 
-test('cannot test with no implementation with expand arg', () => {
+test('tests with no implementation with expand arg', () => {
   const filename = 'only-constructs.test.js';
   const content = `
     it('it', () => {});
@@ -200,7 +200,7 @@ test('cannot test with no implementation with expand arg', () => {
 
   writeFiles(TEST_DIR, {[filename]: content});
   const {stderr, status} = runJest(DIR, ['--expand']);
-  expect(status).toBe(1);
+  expect(status).toBe(0);
 
   const {summary} = extractSummary(stderr);
   expect(cleanStderr(stderr)).toMatchSnapshot();

packages/jest-circus/src/__tests__/circus_it_test_error.test.js

@@ -33,21 +33,21 @@ describe('test/it error throwing', () => {
       circusIt('test1', () => {});
     }).not.toThrowError();
   });
-  it(`it throws error with missing callback function`, () => {
+  it(`it doesn't throw error with missing callback function`, () => {
     expect(() => {
-      // $FlowFixMe: Easy, we're testing runitme errors here
+      // $FlowFixMe: Easy, we're testing runtime errors here
       circusIt('test2');
-    }).toThrowError('Missing second argument. It must be a callback function.');
+    }).not.toThrowError();
   });
   it(`it throws an error when first argument isn't a string`, () => {
     expect(() => {
-      // $FlowFixMe: Easy, we're testing runitme errors here
+      // $FlowFixMe: Easy, we're testing runtime errors here
       circusIt(() => {});
     }).toThrowError(`Invalid first argument, () => {}. It must be a string.`);
   });
   it('it throws an error when callback function is not a function', () => {
     expect(() => {
-      // $FlowFixMe: Easy, we're testing runitme errors here
+      // $FlowFixMe: Easy, we're testing runtime errors here
       circusIt('test4', 'test4b');
     }).toThrowError(
       `Invalid second argument, test4b. It must be a callback function.`,
@@ -58,21 +58,21 @@ describe('test/it error throwing', () => {
       circusTest('test5', () => {});
     }).not.toThrowError();
   });
-  it(`test throws error with missing callback function`, () => {
+  it(`test doesn't throw error with missing callback function`, () => {
     expect(() => {
-      // $FlowFixMe: Easy, we're testing runitme errors here
+      // $FlowFixMe: Easy, we're testing runtime errors here
       circusTest('test6');
-    }).toThrowError('Missing second argument. It must be a callback function.');
+    }).not.toThrowError();
   });
   it(`test throws an error when first argument isn't a string`, () => {
     expect(() => {
-      // $FlowFixMe: Easy, we're testing runitme errors here
+      // $FlowFixMe: Easy, we're testing runtime errors here
       circusTest(() => {});
     }).toThrowError(`Invalid first argument, () => {}. It must be a string.`);
   });
   it('test throws an error when callback function is not a function', () => {
     expect(() => {
-      // $FlowFixMe: Easy, we're testing runitme errors here
+      // $FlowFixMe: Easy, we're testing runtime errors here
       circusTest('test8', 'test8b');
     }).toThrowError(
       `Invalid second argument, test8b. It must be a callback function.`,

packages/jest-circus/src/index.js

@@ -63,10 +63,7 @@ const test = (testName: TestName, fn: TestFn, timeout?: number) => {
       `Invalid first argument, ${testName}. It must be a string.`,
     );
   }
-  if (fn === undefined) {
-    throw new Error('Missing second argument. It must be a callback function.');
-  }
-  if (typeof fn !== 'function') {
+  if (fn !== undefined && typeof fn !== 'function') {
     throw new Error(
       `Invalid second argument, ${fn}. It must be a callback function.`,
     );

packages/jest-jasmine2/src/__tests__/it_test_error.test.js

@@ -9,10 +9,10 @@
 'use strict';
 
 describe('test/it error throwing', () => {
-  it(`it throws error with missing callback function`, () => {
+  it(`it doesn't throw error with missing callback function`, () => {
     expect(() => {
       it('test1');
-    }).toThrowError('Missing second argument. It must be a callback function.');
+    }).not.toThrowError(/argument/i);
   });
   it(`it throws an error when first argument isn't a string`, () => {
     expect(() => {
@@ -26,10 +26,10 @@ describe('test/it error throwing', () => {
       `Invalid second argument, test3b. It must be a callback function.`,
     );
   });
-  test(`test throws error with missing callback function`, () => {
+  test(`test doesn't throw error with missing callback function`, () => {
     expect(() => {
       test('test4');
-    }).toThrowError('Missing second argument. It must be a callback function.');
+    }).not.toThrowError(/argument/i);
   });
   test(`test throws an error when first argument isn't a string`, () => {
     expect(() => {

packages/jest-jasmine2/src/jasmine/Env.js

@@ -448,12 +448,7 @@ export default function(j$) {
           `Invalid first argument, ${description}. It must be a string.`,
         );
       }
-      if (fn === undefined) {
-        throw new Error(
-          'Missing second argument. It must be a callback function.',
-        );
-      }
-      if (typeof fn !== 'function') {
+      if (fn !== undefined && typeof fn !== 'function') {
         throw new Error(
           `Invalid second argument, ${fn}. It must be a callback function.`,
         );