test: Add mockDefault helper for default-export mocks (jaegertracing#3694)

Add global.mockDefault = mod => mod to jest-per-test-setup.js. Wrap all
jest.mock() factories that return a function/component directly with
mockDefault(...) across 33 test files.

In H3, only the setup file changes:
  mod => mod  →  mod => ({ default: mod })
to make all default-export mocks ESM-compatible in Vitest.

Also update ADR section 9 / PR table to mark H2c done.

## AI Usage in this PR (choose one)
See [AI Usage
Policy](https://github.com/jaegertracing/jaeger/blob/main/CONTRIBUTING_GUIDELINES.md#ai-usage-policy).
- [ ] **None**: No AI tools were used in creating this PR
- [ ] **Light**: AI provided minor assistance (formatting, simple
suggestions)
- [ ] **Moderate**: AI helped with code generation or debugging specific
parts
- [x] **Heavy**: AI generated most or all of the code changes

Signed-off-by: Yuri Shkuro <github@ysh.us>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: yurishkuro

docs/adr/0007-vite-plus-migration.md

@@ -386,23 +386,26 @@ called with `new` in production code): `readJsonFile.test.js` (FileReader ×3),
 `DeepDependencies/Graph/index.test.jsx` (LayoutManager), `TracePage/index.test.jsx` (ScrollManager ×3),
 `TracePage/TraceGraph/TraceGraph.test.jsx` (MockLayoutManager).
 
-#### PR H2c — Introduce `mockDefault` helper in affected mock factories
+#### ✅ PR H2c — Introduce `mockDefault` helper in affected mock factories ([#3694](https://github.com/jaegertracing/jaeger-ui/pull/3694))
 
 In Vitest ESM, `vi.mock()` factories must return `{ default: MockComponent }` for default-exported
-modules; Jest CJS interop does not require this. Instead of leaving the full rewrite to H3, introduce
-a helper that makes the flip a one-line change:
+modules; Jest CJS interop does not require this. A helper is introduced so the flip in H3 is a
+single-line change rather than touching every factory:
 
 ```js
-// H2c: add to each affected file — Jest passes mod through unchanged
-function mockDefault(mod) { return mod; }
-jest.mock('./Foo', () => mockDefault(MockFoo));
+// test/jest-per-test-setup.js  (H3: change body to `{ default: mod }`)
+global.mockDefault = mod => mod;
 ```
 
-In H3, change only the function body to `return { default: mod }`. Jest hoists `jest.mock()` factories
-before imports but specifically allows variables whose names start with `mock` in factory scope —
-naming the helper `mockDefault` satisfies this constraint.
+All ~33 `jest.mock()` factories that return a function/component directly have been wrapped:
 
-Alternatively, attach it to `global` in the per-test-setup file for a single-location flip in H3.
+```js
+jest.mock('./Foo', () => mockDefault(function MockFoo() { return <JSX/>; }));
+jest.mock('./Bar', () => mockDefault(() => <JSX/>));
+jest.mock('./Baz', () => mockDefault(jest.fn(() => <JSX/>)));
+```
+
+In H3, only `jest-per-test-setup.js` changes: `mod => mod` → `mod => ({ default: mod })`.
 
 #### PR H3 — The actual switch
 
@@ -599,7 +602,7 @@ confirm no errors or unexpected HTML injection.
 | ✅ H1 | Rename `.test.js` → `.test.jsx` in jaeger-ui (121 files, pure rename) ([#3691](https://github.com/jaegertracing/jaeger-ui/pull/3691)) | None | Done |
 | ✅ H2a | Replace `require()` in test bodies with static `import` ([#3692](https://github.com/jaegertracing/jaeger-ui/pull/3692)) | None | Done |
 | ✅ H2b | Replace arrow function constructors with regular functions (6 files) ([#3693](https://github.com/jaegertracing/jaeger-ui/pull/3693)) | None | Done |
-| H2c | Introduce `mockDefault` helper in affected mock factories | None | After H1 |
+| ✅ H2c | Introduce `mockDefault` helper in affected mock factories ([#3694](https://github.com/jaegertracing/jaeger-ui/pull/3694)) | None | Done |
 | H3 | Vitest switch for jaeger-ui | Unknowns 3, 4, 5, 6 | After H2a–c |
 | G  | Update CLAUDE.md, README, CI workflows | None | After H3 |
 

packages/jaeger-ui/src/actions/jaeger-api.test.js

@@ -1,14 +1,14 @@
 // Copyright (c) 2017 Uber Technologies, Inc.
 // SPDX-License-Identifier: Apache-2.0
 
-jest.mock(
-  'node-fetch',
-  () => () =>
+jest.mock('node-fetch', () =>
+  mockDefault(() =>
     Promise.resolve({
       status: 200,
       data: () => Promise.resolve({ data: null }),
       json: () => Promise.resolve({ data: null }),
     })
+  )
 );
 
 function isPromise(p) {

packages/jaeger-ui/src/actions/path-agnostic-decorations.test.js

@@ -8,7 +8,7 @@ import * as getConfig from '../utils/config/get-config';
 import stringSupplant from '../utils/stringSupplant';
 import JaegerAPI from '../api/jaeger';
 
-jest.mock('lru-memoize', () => () => x => x);
+jest.mock('lru-memoize', () => mockDefault(() => x => x));
 
 describe('getDecoration', () => {
   let getConfigSpy;

packages/jaeger-ui/src/components/App/NotFound.test.jsx

@@ -7,10 +7,10 @@ import { MemoryRouter } from 'react-router-dom';
 import '@testing-library/jest-dom';
 import NotFound from './NotFound';
 
-jest.mock('../../utils/prefix-url', () => () => '/');
-jest.mock('../common/ErrorMessage', () => ({ error }) => (
-  <div data-testid="error-message">{error?.message}</div>
-));
+jest.mock('../../utils/prefix-url', () => mockDefault(() => '/'));
+jest.mock('../common/ErrorMessage', () =>
+  mockDefault(({ error }) => <div data-testid="error-message">{error?.message}</div>)
+);
 
 describe('NotFound tests', () => {
   it('renders error title and home link without error', () => {

packages/jaeger-ui/src/components/App/Page.test.jsx

@@ -1,7 +1,7 @@
 // Copyright (c) 2017 Uber Technologies, Inc.
 // SPDX-License-Identifier: Apache-2.0
 
-jest.mock('./TopNav', () => () => <div />);
+jest.mock('./TopNav', () => mockDefault(() => <div />));
 jest.mock('../../utils/tracking');
 
 import React from 'react';

packages/jaeger-ui/src/components/App/index.dev.test.jsx

@@ -11,15 +11,15 @@ import { render, screen } from '@testing-library/react';
 import '@testing-library/jest-dom';
 import { MemoryRouter } from 'react-router-dom';
 
-jest.mock('./NotFound', () => () => <div data-testid="not-found" />);
-jest.mock('./Page', () => ({ children }) => <div data-testid="page">{children}</div>);
-jest.mock('../DependencyGraph', () => () => <div data-testid="dependency-graph" />);
-jest.mock('../DeepDependencies', () => () => <div data-testid="deep-dependencies" />);
-jest.mock('../QualityMetrics', () => () => <div data-testid="quality-metrics" />);
-jest.mock('../SearchTracePage', () => () => <div data-testid="search-trace" />);
+jest.mock('./NotFound', () => mockDefault(() => <div data-testid="not-found" />));
+jest.mock('./Page', () => mockDefault(({ children }) => <div data-testid="page">{children}</div>));
+jest.mock('../DependencyGraph', () => mockDefault(() => <div data-testid="dependency-graph" />));
+jest.mock('../DeepDependencies', () => mockDefault(() => <div data-testid="deep-dependencies" />));
+jest.mock('../QualityMetrics', () => mockDefault(() => <div data-testid="quality-metrics" />));
+jest.mock('../SearchTracePage', () => mockDefault(() => <div data-testid="search-trace" />));
 jest.mock('../TraceDiff', () => ({ __esModule: true, default: () => <div data-testid="trace-diff" /> }));
 jest.mock('../TracePage', () => ({ __esModule: true, default: () => <div data-testid="trace-page" /> }));
-jest.mock('../Monitor', () => () => <div data-testid="monitor" />);
+jest.mock('../Monitor', () => mockDefault(() => <div data-testid="monitor" />));
 jest.mock('../PlexusDemo', () => ({ __esModule: true, default: () => <div data-testid="plexus-demo" /> }));
 
 jest.mock('../DependencyGraph/url', () => ({ ROUTE_PATH: '/dependencies' }));
@@ -36,8 +36,8 @@ jest.mock('../../api/jaeger', () => ({
   default: { apiRoot: null },
   DEFAULT_API_ROOT: 'http://localhost:16686/api',
 }));
-jest.mock('../../utils/config/process-scripts', () => jest.fn());
-jest.mock('../../utils/prefix-url', () => jest.fn(() => '/prefix'));
+jest.mock('../../utils/config/process-scripts', () => mockDefault(jest.fn()));
+jest.mock('../../utils/prefix-url', () => mockDefault(jest.fn(() => '/prefix')));
 jest.mock('../../utils/configure-store', () => ({
   store: {
     getState: jest.fn(() => ({})),

packages/jaeger-ui/src/components/App/index.test.jsx

@@ -6,15 +6,15 @@ import { render } from '@testing-library/react';
 import '@testing-library/jest-dom';
 import { MemoryRouter } from 'react-router-dom';
 
-jest.mock('./NotFound', () => () => <div data-testid="not-found" />);
-jest.mock('./Page', () => ({ children }) => <div data-testid="page">{children}</div>);
-jest.mock('../DependencyGraph', () => () => <div data-testid="dependency-graph" />);
-jest.mock('../DeepDependencies', () => () => <div data-testid="deep-dependencies" />);
-jest.mock('../QualityMetrics', () => () => <div data-testid="quality-metrics" />);
-jest.mock('../SearchTracePage', () => () => <div data-testid="search-trace" />);
+jest.mock('./NotFound', () => mockDefault(() => <div data-testid="not-found" />));
+jest.mock('./Page', () => mockDefault(({ children }) => <div data-testid="page">{children}</div>));
+jest.mock('../DependencyGraph', () => mockDefault(() => <div data-testid="dependency-graph" />));
+jest.mock('../DeepDependencies', () => mockDefault(() => <div data-testid="deep-dependencies" />));
+jest.mock('../QualityMetrics', () => mockDefault(() => <div data-testid="quality-metrics" />));
+jest.mock('../SearchTracePage', () => mockDefault(() => <div data-testid="search-trace" />));
 jest.mock('../TraceDiff', () => ({ __esModule: true, default: () => <div data-testid="trace-diff" /> }));
 jest.mock('../TracePage', () => ({ __esModule: true, default: () => <div data-testid="trace-page" /> }));
-jest.mock('../Monitor', () => () => <div data-testid="monitor" />);
+jest.mock('../Monitor', () => mockDefault(() => <div data-testid="monitor" />));
 
 jest.mock('../DependencyGraph/url', () => ({ ROUTE_PATH: '/dependencies' }));
 jest.mock('../DeepDependencies/url', () => ({ ROUTE_PATH: '/deep-dependencies' }));
@@ -33,8 +33,8 @@ jest.mock('../../api/jaeger', () => ({
   DEFAULT_API_ROOT: 'http://localhost:16686/api',
 }));
 
-jest.mock('../../utils/config/process-scripts', () => jest.fn());
-jest.mock('../../utils/prefix-url', () => jest.fn(() => '/prefix'));
+jest.mock('../../utils/config/process-scripts', () => mockDefault(jest.fn()));
+jest.mock('../../utils/prefix-url', () => mockDefault(jest.fn(() => '/prefix')));
 
 const createMockHistory = (pathname = '/') => ({
   length: 1,

packages/jaeger-ui/src/components/DeepDependencies/Graph/DdgNodeContent/index.test.jsx

@@ -1,12 +1,14 @@
 // Copyright (c) 2019 Uber Technologies, Inc.
 // SPDX-License-Identifier: Apache-2.0
 
-jest.mock('./calc-positioning', () => () => ({
-  radius: 50,
-  svcWidth: 20,
-  opWidth: 30,
-  svcMarginTop: 10,
-}));
+jest.mock('./calc-positioning', () =>
+  mockDefault(() => ({
+    radius: 50,
+    svcWidth: 20,
+    opWidth: 30,
+    svcMarginTop: 10,
+  }))
+);
 
 // Mutable object so individual tests can control the location without re-creating the mock.
 const mockLocation = { search: '' };

packages/jaeger-ui/src/components/DeepDependencies/Header/index.test.jsx

@@ -10,14 +10,14 @@ import * as track from '../index.track';
 
 jest.mock('./HopsSelector', () => {
   const mockReact = jest.requireActual('react');
-  return function MockHopsSelector(props) {
+  return mockDefault(function MockHopsSelector(props) {
     return mockReact.createElement('div', { 'data-testid': 'hops-selector', ...props });
-  };
+  });
 });
 
 jest.mock('../../common/SearchableSelect', () => {
   const mockReact = jest.requireActual('react');
-  return function MockSearchableSelect(props) {
+  return mockDefault(function MockSearchableSelect(props) {
     const { value, onChange, allowClear, onClear, placeholder, children, className, status } = props;
     // Extract options from children
     const options = mockReact.Children.toArray(children)
@@ -52,43 +52,45 @@ jest.mock('../../common/SearchableSelect', () => {
         value &&
         mockReact.createElement('button', { onClick: onClear, 'data-testid': 'clear-button' }, 'Clear')
     );
-  };
+  });
 });
 
 jest.mock('./LayoutSettings', () => {
   const mockReact = jest.requireActual('react');
-  return function MockLayoutSettings(props) {
+  return mockDefault(function MockLayoutSettings(props) {
     return mockReact.createElement('div', { 'data-testid': 'layout-settings', ...props });
-  };
+  });
 });
 
 jest.mock('../../common/UiFindInput', () => {
   const mockReact = jest.requireActual('react');
-  return mockReact.forwardRef(function MockUiFindInput(props, ref) {
-    const inputRef = mockReact.useRef(null);
-
-    mockReact.useEffect(() => {
-      if (ref) {
-        const current = {
-          focus: () => inputRef.current && inputRef.current.focus(),
-          blur: () => inputRef.current && inputRef.current.blur(),
-          select: () => inputRef.current && inputRef.current.select(),
-          input: inputRef.current,
-        };
-        if (typeof ref === 'function') {
-          ref(current);
-        } else {
-          ref.current = current;
+  return mockDefault(
+    mockReact.forwardRef(function MockUiFindInput(props, ref) {
+      const inputRef = mockReact.useRef(null);
+
+      mockReact.useEffect(() => {
+        if (ref) {
+          const current = {
+            focus: () => inputRef.current && inputRef.current.focus(),
+            blur: () => inputRef.current && inputRef.current.blur(),
+            select: () => inputRef.current && inputRef.current.select(),
+            input: inputRef.current,
+          };
+          if (typeof ref === 'function') {
+            ref(current);
+          } else {
+            ref.current = current;
+          }
         }
-      }
-    });
-
-    return mockReact.createElement('input', {
-      ref: inputRef,
-      'data-testid': 'ui-find-input',
-      ...props.inputProps,
-    });
-  });
+      });
+
+      return mockReact.createElement('input', {
+        ref: inputRef,
+        'data-testid': 'ui-find-input',
+        ...props.inputProps,
+      });
+    })
+  );
 });
 
 describe('<Header>', () => {

packages/jaeger-ui/src/components/DeepDependencies/SidePanel/index.test.jsx

@@ -18,7 +18,7 @@ jest.mock('antd', () => ({
   Table: () => <div data-testid="mock-table">Table Mock</div>,
 }));
 
-jest.mock('./DetailsPanel', () => jest.fn(() => <div data-testid="details-panel" />));
+jest.mock('./DetailsPanel', () => mockDefault(jest.fn(() => <div data-testid="details-panel" />)));
 
 describe('<SidePanel>', () => {
   let getConfigValueSpy;