Allowed describe and it/test to take in functions again (#12484)

Author: JoshuaKGoldberg

Diff for: CHANGELOG.md

@@ -4,6 +4,7 @@
 
 - `[babel-jest]` Export `createTransformer` function ([#12399](https://github.com/facebook/jest/pull/12399))
 - `[expect]` Expose `AsymmetricMatchers`, `MatcherFunction` and `MatcherFunctionWithState` interfaces ([#12363](https://github.com/facebook/jest/pull/12363), [#12376](https://github.com/facebook/jest/pull/12376))
+- `[jest-circus, jest-jasmine2]` Allowed classes and functions as `describe` and `it`/`test` names ([#12484](https://github.com/facebook/jest/pull/12484))
 - `[jest-cli, jest-config]` [**BREAKING**] Remove `testURL` config, use `testEnvironmentOptions.url` instead ([#10797](https://github.com/facebook/jest/pull/10797))
 - `[jest-config]` [**BREAKING**] Stop shipping `jest-environment-jsdom` by default ([#12354](https://github.com/facebook/jest/pull/12354))
 - `[jest-config]` [**BREAKING**] Stop shipping `jest-jasmine2` by default ([#12355](https://github.com/facebook/jest/pull/12355))

Diff for: e2e/__tests__/__snapshots__/globals.test.ts.snap

@@ -81,13 +81,26 @@ Time:        <<REPLACED>>
 Ran all test suites."
 `;
 
-exports[`function as descriptor 1`] = `
+exports[`function as describe() descriptor 1`] = `
 "PASS __tests__/functionAsDescriptor.test.js
   Foo
     ✓ it"
 `;
 
-exports[`function as descriptor 2`] = `
+exports[`function as describe() descriptor 2`] = `
+"Test Suites: 1 passed, 1 total
+Tests:       1 passed, 1 total
+Snapshots:   0 total
+Time:        <<REPLACED>>
+Ran all test suites."
+`;
+
+exports[`function as it() descriptor 1`] = `
+"PASS __tests__/functionAsDescriptor.test.js
+  ✓ Foo"
+`;
+
+exports[`function as it() descriptor 2`] = `
 "Test Suites: 1 passed, 1 total
 Tests:       1 passed, 1 total
 Snapshots:   0 total

Diff for: e2e/__tests__/globals.test.ts

@@ -262,7 +262,7 @@ test('cannot test with no implementation with expand arg', () => {
   expect(exitCode).toBe(1);
 });
 
-test('function as descriptor', () => {
+test('function as describe() descriptor', () => {
   const filename = 'functionAsDescriptor.test.js';
   const content = `
     function Foo() {}
@@ -279,3 +279,19 @@ test('function as descriptor', () => {
   expect(summary).toMatchSnapshot();
   expect(exitCode).toBe(0);
 });
+
+test('function as it() descriptor', () => {
+  const filename = 'functionAsDescriptor.test.js';
+  const content = `
+    function Foo() {}
+    it(Foo, () => {});
+  `;
+
+  writeFiles(TEST_DIR, {[filename]: content});
+  const {stderr, exitCode} = runJest(DIR);
+
+  const {summary, rest} = extractSummary(stderr);
+  expect(rest).toMatchSnapshot();
+  expect(summary).toMatchSnapshot();
+  expect(exitCode).toBe(0);
+});

Diff for: packages/jest-circus/src/__tests__/__snapshots__/baseTest.test.ts.snap

@@ -33,6 +33,24 @@ run_finish
 unhandledErrors: 0"
 `;
 
+exports[`function descriptors 1`] = `
+"start_describe_definition: describer
+add_test: One
+finish_describe_definition: describer
+run_start
+run_describe_start: ROOT_DESCRIBE_BLOCK
+run_describe_start: describer
+test_start: One
+test_fn_start: One
+test_fn_success: One
+test_done: One
+run_describe_finish: describer
+run_describe_finish: ROOT_DESCRIBE_BLOCK
+run_finish
+
+unhandledErrors: 0"
+`;
+
 exports[`simple test 1`] = `
 "start_describe_definition: describe
 add_hook: beforeEach

Diff for: packages/jest-circus/src/__tests__/baseTest.test.ts

@@ -20,6 +20,16 @@ test('simple test', () => {
   expect(stdout).toMatchSnapshot();
 });
 
+test('function descriptors', () => {
+  const {stdout} = runTest(`
+    describe(function describer() {}, () => {
+      test(class One {}, () => {});
+    })
+  `);
+
+  expect(stdout).toMatchSnapshot();
+});
+
 test('failures', () => {
   const {stdout} = runTest(`
     describe('describe', () => {

Diff for: packages/jest-circus/src/__tests__/circusItTestError.test.ts

@@ -35,11 +35,13 @@ describe('test/it error throwing', () => {
       'Missing second argument. It must be a callback function. Perhaps you want to use `test.todo` for a test placeholder.',
     );
   });
-  it("it throws an error when first argument isn't a string", () => {
+  it("it throws an error when first argument isn't valid", () => {
     expect(() => {
       // @ts-expect-error: Easy, we're testing runtime errors here
       circusIt(() => {});
-    }).toThrowError('Invalid first argument, () => {}. It must be a string.');
+    }).toThrowError(
+      'Invalid first argument, () => {}. It must be a named class, named function, number, or string.',
+    );
   });
   it('it throws an error when callback function is not a function', () => {
     expect(() => {
@@ -66,7 +68,9 @@ describe('test/it error throwing', () => {
     expect(() => {
       // @ts-expect-error: Easy, we're testing runtime errors here
       circusTest(() => {});
-    }).toThrowError('Invalid first argument, () => {}. It must be a string.');
+    }).toThrowError(
+      'Invalid first argument, () => {}. It must be a named class, named function, number, or string.',
+    );
   });
   it('test throws an error when callback function is not a function', () => {
     expect(() => {

Diff for: packages/jest-circus/src/index.ts

@@ -7,24 +7,24 @@
 
 import type {Circus, Global} from '@jest/types';
 import {bind as bindEach} from 'jest-each';
-import {ErrorWithStack, isPromise} from 'jest-util';
+import {ErrorWithStack, convertDescriptorToString, isPromise} from 'jest-util';
 import {dispatchSync} from './state';
 
 export {setState, getState, resetState} from './state';
 export {default as run} from './run';
 
 type THook = (fn: Circus.HookFn, timeout?: number) => void;
 type DescribeFn = (
-  blockName: Circus.BlockName,
+  blockName: Circus.BlockNameLike,
   blockFn: Circus.BlockFn,
 ) => void;
 
 const describe = (() => {
-  const describe = (blockName: Circus.BlockName, blockFn: Circus.BlockFn) =>
+  const describe = (blockName: Circus.BlockNameLike, blockFn: Circus.BlockFn) =>
     _dispatchDescribe(blockFn, blockName, describe);
-  const only = (blockName: Circus.BlockName, blockFn: Circus.BlockFn) =>
+  const only = (blockName: Circus.BlockNameLike, blockFn: Circus.BlockFn) =>
     _dispatchDescribe(blockFn, blockName, only, 'only');
-  const skip = (blockName: Circus.BlockName, blockFn: Circus.BlockFn) =>
+  const skip = (blockName: Circus.BlockNameLike, blockFn: Circus.BlockFn) =>
     _dispatchDescribe(blockFn, blockName, skip, 'skip');
 
   describe.each = bindEach(describe, false);
@@ -40,7 +40,7 @@ const describe = (() => {
 
 const _dispatchDescribe = (
   blockFn: Circus.BlockFn,
-  blockName: Circus.BlockName,
+  blockName: Circus.BlockNameLike,
   describeFn: DescribeFn,
   mode?: Circus.BlockMode,
 ) => {
@@ -54,6 +54,13 @@ const _dispatchDescribe = (
     asyncError.message = `Invalid second argument, ${blockFn}. It must be a callback function.`;
     throw asyncError;
   }
+  try {
+    blockName = convertDescriptorToString(blockName);
+  } catch (error) {
+    asyncError.message = (error as Error).message;
+    throw asyncError;
+  }
+
   dispatchSync({
     asyncError,
     blockName,
@@ -107,22 +114,22 @@ const afterAll: THook = (fn, timeout) =>
 
 const test: Global.It = (() => {
   const test = (
-    testName: Circus.TestName,
+    testName: Circus.TestNameLike,
     fn: Circus.TestFn,
     timeout?: number,
   ): void => _addTest(testName, undefined, fn, test, timeout);
   const skip = (
-    testName: Circus.TestName,
+    testName: Circus.TestNameLike,
     fn?: Circus.TestFn,
     timeout?: number,
   ): void => _addTest(testName, 'skip', fn, skip, timeout);
   const only = (
-    testName: Circus.TestName,
+    testName: Circus.TestNameLike,
     fn: Circus.TestFn,
     timeout?: number,
   ): void => _addTest(testName, 'only', fn, test.only, timeout);
 
-  test.todo = (testName: Circus.TestName, ...rest: Array<any>): void => {
+  test.todo = (testName: Circus.TestNameLike, ...rest: Array<any>): void => {
     if (rest.length > 0 || typeof testName !== 'string') {
       throw new ErrorWithStack(
         'Todo must be called with only a description.',
@@ -133,23 +140,25 @@ const test: Global.It = (() => {
   };
 
   const _addTest = (
-    testName: Circus.TestName,
+    testName: Circus.TestNameLike,
     mode: Circus.TestMode,
     fn: Circus.TestFn | undefined,
     testFn: (
-      testName: Circus.TestName,
+      testName: Circus.TestNameLike,
       fn: Circus.TestFn,
       timeout?: number,
     ) => void,
     timeout?: number,
   ) => {
     const asyncError = new ErrorWithStack(undefined, testFn);
 
-    if (typeof testName !== 'string') {
-      asyncError.message = `Invalid first argument, ${testName}. It must be a string.`;
-
+    try {
+      testName = convertDescriptorToString(testName);
+    } catch (error) {
+      asyncError.message = (error as Error).message;
       throw asyncError;
     }
+
     if (fn === undefined) {
       asyncError.message =
         'Missing second argument. It must be a callback function. Perhaps you want to use `test.todo` for a test placeholder.';

Diff for: packages/jest-circus/src/legacy-code-todo-rewrite/jestAdapterInit.ts

@@ -78,7 +78,7 @@ export const initialize = async ({
 
   globalsObject.test.concurrent = (test => {
     const concurrent = (
-      testName: string,
+      testName: Global.TestNameLike,
       testFn: Global.ConcurrentTestFn,
       timeout?: number,
     ) => {
@@ -96,7 +96,7 @@ export const initialize = async ({
     };
 
     const only = (
-      testName: string,
+      testName: Global.TestNameLike,
       testFn: Global.ConcurrentTestFn,
       timeout?: number,
     ) => {

Diff for: packages/jest-each/src/bind.ts

@@ -7,7 +7,7 @@
  */
 
 import type {Global} from '@jest/types';
-import {ErrorWithStack} from 'jest-util';
+import {ErrorWithStack, convertDescriptorToString} from 'jest-util';
 import convertArrayTable from './table/array';
 import convertTemplateTable from './table/template';
 import {
@@ -37,10 +37,11 @@ export default function bind<EachCallback extends Global.TestCallback>(
     ...taggedTemplateData: Global.TemplateData
   ) =>
     function eachBind(
-      title: string,
+      title: Global.BlockNameLike,
       test: Global.EachTestFn<EachCallback>,
       timeout?: number,
     ): void {
+      title = convertDescriptorToString(title);
       try {
         const tests = isArrayTable(taggedTemplateData)
           ? buildArrayTests(title, table)

Diff for: packages/jest-jasmine2/src/__tests__/itTestError.test.ts

@@ -14,11 +14,13 @@ describe('test/it error throwing', () => {
       'Missing second argument. It must be a callback function. Perhaps you want to use `test.todo` for a test placeholder.',
     );
   });
-  it("it throws an error when first argument isn't a string", () => {
+  it("it throws an error when first argument isn't valid", () => {
     expect(() => {
       // @ts-expect-error
       it(() => {});
-    }).toThrowError('Invalid first argument, () => {}. It must be a string.');
+    }).toThrowError(
+      'Invalid first argument, () => {}. It must be a named class, named function, number, or string.',
+    );
   });
   it('it throws an error when callback function is not a function', () => {
     expect(() => {
@@ -35,11 +37,13 @@ describe('test/it error throwing', () => {
       'Missing second argument. It must be a callback function. Perhaps you want to use `test.todo` for a test placeholder.',
     );
   });
-  test("test throws an error when first argument isn't a string", () => {
+  test("test throws an error when first argument isn't valid", () => {
     expect(() => {
       // @ts-expect-error
       test(() => {});
-    }).toThrowError('Invalid first argument, () => {}. It must be a string.');
+    }).toThrowError(
+      'Invalid first argument, () => {}. It must be a named class, named function, number, or string.',
+    );
   });
   test('test throws an error when callback function is not a function', () => {
     expect(() => {