[code-infra] Adopt `@mui/internal-test-utils` #927

Janpot · 2025-12-04T11:59:04Z

Makes it possible to iterate faster on this module, the goal is to thin it out and remove unnecessary wrapper APIs.

Had to make a bunch of updates as well, most notable

emotion wrapper is now optional and can be initialized when calling setupVitest. This allows us to make these emotion peer dependencies optional too
Projects will need to import setupVitest and call the function. We can't rely on module side effects because we use isolate:false and that caches modules imported by the setup script between suites
Updated toErrorDev to handle both sync and async functions. (There was a broken test in X relying on this)

Integrations:

mui-bot · 2025-12-04T12:02:33Z

Bundle size report

Bundle	Parsed size	Gzip size
@base-ui-components/react	0B^(0.00%)	0B^(0.00%)
@mui/x-charts-pro	0B^(0.00%)	0B^(0.00%)

Details of bundle changes

Check out the code infra dashboard for more information about this PR.

Copilot

Pull request overview

This PR introduces the @mui/internal-test-utils package to the code-infra repository, consolidating testing utilities to enable faster iteration and development. The package provides a comprehensive suite of test utilities including renderers, matchers, conformance testing, and helper functions for React component testing.

Key Changes

New test-utils package with complete TypeScript and Vitest configuration
Custom chai matchers for accessibility, focus, and style assertions
Conformance testing framework for component consistency
React Testing Library wrapper with enhanced functionality

Reviewed changes

Copilot reviewed 22 out of 23 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
packages/test-utils/package.json	Package definition with dependencies and exports for the new test utilities
packages/test-utils/tsconfig.json	TypeScript configuration for the test-utils package
packages/test-utils/tsconfig.build.json	Build-specific TypeScript configuration
packages/test-utils/vitest.config.mts	Vitest test configuration with jsdom environment setup
packages/test-utils/src/index.ts	Main entry point exporting all test utilities
packages/test-utils/src/setupVitest.ts	Vitest setup with console error/warning suppression
packages/test-utils/src/setupVitestBrowser.ts	Browser environment setup with Touch API polyfill
packages/test-utils/src/initMatchers.ts	Initializes chai matchers for tests
packages/test-utils/src/initMatchers.test.js	Test suite for custom error/warning matchers
packages/test-utils/src/initPlaywrightMatchers.ts	Playwright-specific matchers for browser testing
packages/test-utils/src/chaiPlugin.ts	Custom chai assertions for accessibility and styling
packages/test-utils/src/chai.types.ts	TypeScript type definitions for custom chai matchers
packages/test-utils/src/createRenderer.tsx	Enhanced React Testing Library renderer with emotion cache
packages/test-utils/src/createRenderer.test.jsx	Tests for the custom renderer functionality
packages/test-utils/src/createDescribe.ts	Utility for creating describe blocks with skip/only support
packages/test-utils/src/describeConformance.tsx	Comprehensive conformance testing framework for components
packages/test-utils/src/components.tsx	Test helper components (ErrorBoundary, RenderCounter)
packages/test-utils/src/focusVisible.ts	Focus management utilities for testing
packages/test-utils/src/flushMicrotasks.ts	Async utility for flushing microtasks
packages/test-utils/src/fireDiscreteEvent.ts	Discrete event firing utilities for React 17/18 compatibility
packages/test-utils/src/env.ts	Environment detection utilities
packages/code-infra/src/eslint/material-ui/config.mjs	ESLint configuration update to support .jsx extension

packages/test-utils/package.json

packages/test-utils/tsconfig.json

packages/test-utils/src/initMatchers.test.js

packages/test-utils/src/chaiPlugin.ts

packages/test-utils/src/focusVisible.ts

packages/test-utils/src/index.ts

packages/test-utils/src/describeConformance.tsx

Co-authored-by: Copilot <[email protected]> Signed-off-by: Jan Potoms <[email protected]>

Janpot · 2025-12-15T12:13:21Z

.browserslistrc

@@ -0,0 +1,20 @@
+# On update, sync references where "#stable-snapshot" is mentioned in the codebase.
+[stable]
+baseline widely available


Noticed we were shipping regenerator runtime because of a missing browserslistrc.

@brijeshb42 Would it be possible to have a more modern default when browserslistrc is missing?

We could add that, or fail directly asking to create a browserlistrc file if it doesn't exist. We shouldn't assume the supported browsers IMO.

Copilot

Pull request overview

Copilot reviewed 23 out of 25 changed files in this pull request and generated 4 comments.

packages/test-utils/src/chaiPlugin.ts

packages/test-utils/src/setupVitest.ts

packages/test-utils/src/chaiPlugin.ts

packages/test-utils/src/describeConformance.tsx

Co-authored-by: Copilot <[email protected]> Signed-off-by: Jan Potoms <[email protected]>

JCQuintas · 2025-12-15T15:49:42Z

packages/test-utils/src/configure.ts

+  emotion: false,
+};
+
+export const config: Configuration = defaultConfig;


Should this be readonly?

JCQuintas · 2025-12-15T16:04:27Z

packages/test-utils/src/configure.ts

@@ -0,0 +1,13 @@
+export interface Configuration {
+  emotion: boolean;


Should we document the usage of the prop?

Suggested change

emotion: boolean;

/**

* The emotion wrapper is optional.

* If you package uses emotion, install ... and set this to true.

*/

emotion: boolean;

JCQuintas · 2025-12-15T16:09:14Z

packages/test-utils/src/createDescribe.ts

+  skip: (...args: P) => void;
+  only: (...args: P) => void;
+};
+export default <P extends any[]>(


Can we document this function so if someone who is thinking of using it understands possible drawbacks?

I understand it is used in many places in order to hide complexity. But it makes testing errors more opaque and harder to understand.

JCQuintas · 2025-12-15T16:19:33Z

packages/test-utils/src/createRenderer.tsx

+
+export type ClockConfig = undefined | number | Date;
+
+function createClock(


In X I've moved all tests that used fake clock from this implementation to the actual vi.useFakeTimers/vi.vi.setSystemTime as this was creating a lot of unnecessary errors.

Since the createRenderer is usually called once for each file, it then became a flag that changed all the tests in a file to use fake timers or not.

When used in conjunction with createDescribe, which could have a lot of tests inside, it created a mess in which some components were being tested with fake timers, while other weren't.

I would be in favour of completely removing it as there are only about 18 uses in material-ui

JCQuintas · 2025-12-15T16:26:28Z

packages/test-utils/src/createRenderer.tsx

+import * as ReactDOMServer from 'react-dom/server';
+import { useFakeTimers } from 'sinon';
+import { beforeEach, afterEach, beforeAll, vi } from 'vitest';
+import type { EmotionCache } from '@emotion/cache';


Doesn't this causes issues if emotion is not installed?

JCQuintas · 2025-12-15T16:27:35Z

packages/test-utils/src/createRenderer.tsx

+  return originalFireEventKeyUp(element, options);
+};
+
+export function fireTouchChangedEvent(


There is a lot going on on this file that could be split into different files, but we can do it in a different pass

JCQuintas · 2025-12-15T16:31:43Z

packages/test-utils/src/fireDiscreteEvent.ts

+ * @param {() => void} callback
+ * @returns {void}
+ */
+function withMissingActWarningsIgnored(callback: () => void) {


Couldn't we remove the implementation in this file altogether?

JCQuintas · 2025-12-15T16:33:31Z

packages/test-utils/src/setupVitest.ts

+
+  chai.use(chaiPlugin);
+
+  if (failOnConsoleEnabed) {


typo

Suggested change

if (failOnConsoleEnabed) {

if (failOnConsoleEnabled) {

[code-infra] Adopt @mui/internal-test-utils

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oliviertassinari temporarily deployed to test-utils - mui-tools-public PR #927 December 4, 2025 11:59 — with Render Destroyed

Janpot added the scope: code-infra Involves the code-infra product (https://www.notion.so/mui-org/5562c14178aa42af97bc1fa5114000cd). label Dec 4, 2025

remove rimraf

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oliviertassinari deployed to test-utils - mui-tools-public PR #927 December 4, 2025 12:00 — with Render View deployment

port test utils

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oliviertassinari deployed to test-utils - mui-tools-public PR #927 December 4, 2025 13:17 — with Render View deployment

Janpot added 5 commits December 4, 2025 14:34

some cleanups already

56da4e5

remove unused

7b07776

Update fireDiscreteEvent.ts

5dc801f

Update package.json

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Update createRenderer.tsx

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Janpot requested review from a team and michaldudak December 4, 2025 15:58

bdf

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Janpot and others added 10 commits December 4, 2025 20:00

Update packages/test-utils/package.json

8baea65

Co-authored-by: Copilot <[email protected]> Signed-off-by: Jan Potoms <[email protected]>

Update packages/test-utils/src/index.ts

007ce88

Co-authored-by: Copilot <[email protected]> Signed-off-by: Jan Potoms <[email protected]>

Merge branch 'master' into test-utils

fea5ed0

Make emotion optional

4035cde

update

b890445

Update createRenderer.tsx

9d8b68f

Update packages/test-utils/src/initMatchers.test.js

87f9047

Co-authored-by: Copilot <[email protected]> Signed-off-by: Jan Potoms <[email protected]>

Update packages/test-utils/src/describeConformance.tsx

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Co-authored-by: Copilot <[email protected]> Signed-off-by: Jan Potoms <[email protected]>

Update describeConformance.tsx

32ee860

Update describeConformance.tsx

a3a8d06

Merge branch 'master' into test-utils

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oliviertassinari had a problem deploying to test-utils - mui-tools-public PR #927 December 12, 2025 15:39 — with Render Failure

github-actions bot removed the PR: out-of-date The pull request has merge conflicts and can't be merged. label Dec 12, 2025

Janpot added 2 commits December 12, 2025 16:52

esm compat

cb66536

Update createRenderer.tsx

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github-actions bot added the PR: out-of-date The pull request has merge conflicts and can't be merged. label Dec 12, 2025

Janpot added 2 commits December 15, 2025 04:01

Update createRenderer.tsx

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Merge branch 'master' into test-utils

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oliviertassinari had a problem deploying to test-utils - mui-tools-public PR #927 December 15, 2025 03:05 — with Render Failure

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Janpot added 2 commits December 15, 2025 10:37

Update createRenderer.tsx

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Merge branch 'master' into test-utils

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oliviertassinari had a problem deploying to test-utils - mui-tools-public PR #927 December 15, 2025 09:38 — with Render Failure

Merge branch 'master' into test-utils

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oliviertassinari had a problem deploying to test-utils - mui-tools-public PR #927 December 15, 2025 09:45 — with Render Failure

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Update pnpm-lock.yaml

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oliviertassinari had a problem deploying to test-utils - mui-tools-public PR #927 December 15, 2025 09:48 — with Render Failure

Janpot added 3 commits December 15, 2025 10:57

Update setupVitest.ts

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Update setupVitest.ts

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Update setupVitest.ts

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Janpot and others added 3 commits December 15, 2025 13:26

Update packages/test-utils/src/chaiPlugin.ts

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Co-authored-by: Copilot <[email protected]> Signed-off-by: Jan Potoms <[email protected]>

Update chaiPlugin.ts

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Update setupVitest.ts

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JCQuintas reviewed Dec 15, 2025

View reviewed changes

		@@ -0,0 +1,13 @@
		export interface Configuration {
		emotion: boolean;


		export type ClockConfig = undefined \| number \| Date;

		function createClock(

[code-infra] Adopt @mui/internal-test-utils #927

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[code-infra] Adopt `@mui/internal-test-utils` #927

[code-infra] Adopt `@mui/internal-test-utils` #927

Janpot commented Dec 4, 2025 •

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