only console.warn for now

CHANGELOG.md

@@ -11,7 +11,7 @@
 - `[jest-config]` Print error information on preset normalization error ([#7935](https://github.com/facebook/jest/pull/7935))
 - `[jest-haste-map]` Add `skipPackageJson` option ([#7778](https://github.com/facebook/jest/pull/7778))
 - `[jest-get-type]` Add `isPrimitive` function ([#7708](https://github.com/facebook/jest/pull/7708))
-- `[jest-circus/jest-jasmine2]` Fail test suite if describe returns a Promise ([#7852](https://github.com/facebook/jest/pull/7852))
+- `[jest-circus/jest-jasmine2]` Warn if describe returns a value ([#7852](https://github.com/facebook/jest/pull/7852))
 - `[jest-util]` Add `isPromise` ([#7852](https://github.com/facebook/jest/pull/7852))
 
 ### Fixes

e2e/__tests__/declarationErrors.test.ts

@@ -0,0 +1,26 @@
+/**
+ * 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.
+ */
+
+import runJest from '../runJest';
+
+it('warns if describe returns a Promise', () => {
+  const result = runJest('declaration-errors', [
+    'describeReturnPromise.test.js',
+  ]);
+
+  expect(result.status).toBe(0);
+  expect(result.stdout).toMatch(/Tests must be defined synchronously/);
+});
+
+it('warns if describe returns something', () => {
+  const result = runJest('declaration-errors', [
+    'describeReturnSomething.test.js',
+  ]);
+
+  expect(result.status).toBe(0);
+  expect(result.stdout).toMatch(/"describe" callback must not return a value/);
+});

e2e/__tests__/jasmineAsync.test.ts

@@ -83,13 +83,6 @@ describe('async jasmine', () => {
     expect(json.numPendingTests).toBe(1);
   });
 
-  it('fails if describe returns a Promise', () => {
-    const result = runJest('jasmine-async', ['promiseDescribeFails.test.js']);
-
-    expect(result.status).toBe(1);
-    expect(result.stderr).toMatch(/Tests must be defined synchronously/);
-  });
-
   it('throws when not a promise is returned', () => {
     const result = runWithJson('jasmine-async', ['returningValues.test.js']);
     const json = result.json;

e2e/jasmine-async/__tests__/promiseDescribeFails.test.js → e2e/declaration-errors/__tests__/describeReturnPromise.test.js

@@ -9,12 +9,12 @@
 'use strict';
 
 // TODO after dropping Node 6: Convert to async-await
-// describe('Promise describe fails', async () => {
+// describe('Promise describe warns', async () => {
+//   it('t', () => {});
 //   await Promise.resolve();
-//   it('not declared', () => {});
 // });
 
-describe('Promise describe fails', () =>
-  Promise.resolve().then(() => {
-    it('not declared', () => {});
-  }));
+describe('Promise describe warns', () => {
+  it('t', () => {});
+  return Promise.resolve();
+});

e2e/declaration-errors/__tests__/describeReturnSomething.test.js

@@ -0,0 +1,14 @@
+/**
+ * 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.
+ *
+ */
+
+'use strict';
+
+describe('describe return warns', () => {
+  it('t', () => {});
+  return 42;
+});

e2e/declaration-errors/package.json

@@ -0,0 +1,5 @@
+{
+  "jest": {
+    "testEnvironment": "node"
+  }
+}

packages/jest-circus/src/index.ts

@@ -64,12 +64,20 @@ const _dispatchDescribe = (
     name: 'start_describe_definition',
   });
   const describeReturn = blockFn();
+
+  // TODO throw in Jest 25
   if (isPromise(describeReturn)) {
-    throw new ErrorWithStack(
-      'Returning a Promise from "describe" is not supported. Tests must be defined synchronously.',
-      describeFn,
+    console.warn(
+      'Returning a Promise from "describe" is not supported. Tests must be defined synchronously.\n' +
+        'Returning a value from "describe" will fail the test in a future version of Jest.',
+    );
+  } else if (describeReturn !== undefined) {
+    console.warn(
+      'A "describe" callback must not return a value.\n' +
+        'Returning a value from "describe" will fail the test in a future version of Jest.',
     );
   }
+
   dispatch({blockName, mode, name: 'finish_describe_definition'});
 };
 

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

@@ -376,9 +376,16 @@ export default function(j$) {
         declarationError = e;
       }
 
+      // TODO throw in Jest 25: declarationError = new Error
       if (isPromise(describeReturnValue)) {
-        declarationError = new Error(
-          'Returning a Promise from "describe" is not supported. Tests must be defined synchronously.',
+        console.warn(
+          'Returning a Promise from "describe" is not supported. Tests must be defined synchronously.\n' +
+            'Returning a value from "describe" will fail the test in a future version of Jest.',
+        );
+      } else if (describeReturnValue !== undefined) {
+        console.warn(
+          'A "describe" callback must not return a value.\n' +
+            'Returning a value from "describe" will fail the test in a future version of Jest.',
         );
       }
 

yarn.lock

@@ -1784,14 +1784,6 @@
     "@types/prop-types" "*"
     csstype "^2.2.0"
 
-"@types/readable-stream@^2.3.0":
-  version "2.3.1"
-  resolved "https://registry.yarnpkg.com/@types/readable-stream/-/readable-stream-2.3.1.tgz#59d458b51c84c585caea06e296e2225057c9ea8e"
-  integrity sha512-Dp6t95yGEOm2y669mQrSl0kUg+oL+bJEiCWMyDv0Yq+FcVvjzNRLTAqJks2LDBYYrazZXNI7lZXq3lp7MOvt4A==
-  dependencies:
-    "@types/node" "*"
-    safe-buffer "*"
-
 "@types/resolve@*":
   version "0.0.8"
   resolved "https://registry.yarnpkg.com/@types/resolve/-/resolve-0.0.8.tgz#f26074d238e02659e323ce1a13d041eee280e194"
@@ -11516,7 +11508,7 @@ rxjs@^6.4.0:
   dependencies:
     tslib "^1.9.0"
 
-safe-buffer@*, safe-buffer@5.1.2, safe-buffer@^5.0.1, safe-buffer@^5.1.0, safe-buffer@^5.1.1, safe-buffer@^5.1.2, safe-buffer@~5.1.0, safe-buffer@~5.1.1:
+safe-buffer@5.1.2, safe-buffer@^5.0.1, safe-buffer@^5.1.0, safe-buffer@^5.1.1, safe-buffer@^5.1.2, safe-buffer@~5.1.0, safe-buffer@~5.1.1:
   version "5.1.2"
   resolved "https://registry.yarnpkg.com/safe-buffer/-/safe-buffer-5.1.2.tgz#991ec69d296e0313747d59bdfd2b745c35f8828d"
   integrity sha512-Gd2UZBJDkXlY7GbJxfsE8/nvKkUEU1G38c1siN6QP6a9PT9MmHB8GnpscSmMJSoF8LOIrt8ud/wPtojys4G6+g==