feat: Istanbul Coverage only for changed Files

examples/react-istanbul-coverage/package.json

@@ -0,0 +1,27 @@
+{
+  "name": "vitest-coverage",
+  "type": "module",
+  "version": "0.0.0",
+  "private": true,
+  "scripts": {
+    "dev": "vite",
+    "build": "vite build",
+    "preview": "vite preview",
+    "test": "vitest --coverage"
+  },
+  "dependencies": {
+    "react": "^18.2.0",
+    "react-dom": "^18.2.0"
+  },
+  "devDependencies": {
+    "@testing-library/react": "^13.4.0",
+    "@types/react": "^18.0.24",
+    "@types/react-dom": "^18.0.8",
+    "@vitejs/plugin-react": "^2.2.0",
+    "@vitest/coverage-istanbul": "latest",
+    "@vitest/ui": "latest",
+    "jsdom": "^20.0.2",
+    "vite": "latest",
+    "vitest": "latest"
+  }
+}

examples/react-istanbul-coverage/src/App.css

@@ -0,0 +1,41 @@
+#root {
+  max-width: 1280px;
+  margin: 0 auto;
+  padding: 2rem;
+  text-align: center;
+}
+
+.logo {
+  height: 6em;
+  padding: 1.5em;
+  will-change: filter;
+}
+.logo:hover {
+  filter: drop-shadow(0 0 2em #646cffaa);
+}
+.logo.react:hover {
+  filter: drop-shadow(0 0 2em #61dafbaa);
+}
+
+@keyframes logo-spin {
+  from {
+    transform: rotate(0deg);
+  }
+  to {
+    transform: rotate(360deg);
+  }
+}
+
+@media (prefers-reduced-motion: no-preference) {
+  a:nth-of-type(2) .logo {
+    animation: logo-spin infinite 20s linear;
+  }
+}
+
+.card {
+  padding: 2em;
+}
+
+.read-the-docs {
+  color: #888;
+}

examples/react-istanbul-coverage/src/App.jsx

@@ -0,0 +1,34 @@
+import { useState } from 'react'
+import reactLogo from './assets/react.svg'
+import './App.css'
+
+function App() {
+  const [count, setCount] = useState(0)
+
+  return (
+    <div className="App">
+      <div>
+        <a href="https://vitejs.dev" target="_blank">
+          <img src="/vite.svg" className="logo" alt="Vite logo" />
+        </a>
+        <a href="https://reactjs.org" target="_blank">
+          <img src={reactLogo} className="logo react" alt="React logo" />
+        </a>
+      </div>
+      <h1>Vite + React</h1>
+      <div className="card">
+        <button onClick={() => setCount((count) => count + 1)}>
+          count is {count}
+        </button>
+        <p>
+          Edit <code>src/App.jsx</code> and save to test HMR
+        </p>
+      </div>
+      <p className="read-the-docs">
+        Click on the Vite and React logos to learn more
+      </p>
+    </div>
+  )
+}
+
+export default App

examples/react-istanbul-coverage/src/App.test.jsx

@@ -0,0 +1,10 @@
+import { render, screen } from "@testing-library/react";
+import { expect, it } from "vitest";
+import App from "./App";
+
+it('should render heading', () => {
+    render(<App />)
+    expect(screen.getByRole('heading', {name: /Vite \+ React/}))
+    const codeElement = screen.getByText(/src\/App.jsx/i);
+    expect(codeElement).toBeDefined()
+})

examples/react-istanbul-coverage/src/Component.jsx

@@ -0,0 +1,14 @@
+import { Children, useState } from "react"
+
+export const Component = ({children}) => {
+    const [isExpanded, setIsExpanded] = useState(false)
+
+    const handleToggle = () => {
+        setIsExpanded(prev => !prev)
+    }
+
+    return <div>
+        <button onClick={handleToggle}>{isExpanded ? 'Collapse' : 'Expand'}</button>
+        {isExpanded && children}
+    </div>
+}

examples/react-istanbul-coverage/src/Component.test.jsx

@@ -0,0 +1,9 @@
+import { render, screen } from "@testing-library/react";
+import { expect, it } from "vitest";
+import { Component } from "./Component";
+
+it('should not render content', () => {
+    render(<Component>Content</Component>)
+    expect(screen.getByRole('button', {name: /Expand/}))
+    expect(screen.queryByText(/Content/)).toBeNull()
+})

examples/react-istanbul-coverage/src/index.css

@@ -0,0 +1,70 @@
+:root {
+  font-family: Inter, Avenir, Helvetica, Arial, sans-serif;
+  font-size: 16px;
+  line-height: 24px;
+  font-weight: 400;
+
+  color-scheme: light dark;
+  color: rgba(255, 255, 255, 0.87);
+  background-color: #242424;
+
+  font-synthesis: none;
+  text-rendering: optimizeLegibility;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+  -webkit-text-size-adjust: 100%;
+}
+
+a {
+  font-weight: 500;
+  color: #646cff;
+  text-decoration: inherit;
+}
+a:hover {
+  color: #535bf2;
+}
+
+body {
+  margin: 0;
+  display: flex;
+  place-items: center;
+  min-width: 320px;
+  min-height: 100vh;
+}
+
+h1 {
+  font-size: 3.2em;
+  line-height: 1.1;
+}
+
+button {
+  border-radius: 8px;
+  border: 1px solid transparent;
+  padding: 0.6em 1.2em;
+  font-size: 1em;
+  font-weight: 500;
+  font-family: inherit;
+  background-color: #1a1a1a;
+  cursor: pointer;
+  transition: border-color 0.25s;
+}
+button:hover {
+  border-color: #646cff;
+}
+button:focus,
+button:focus-visible {
+  outline: 4px auto -webkit-focus-ring-color;
+}
+
+@media (prefers-color-scheme: light) {
+  :root {
+    color: #213547;
+    background-color: #ffffff;
+  }
+  a:hover {
+    color: #747bff;
+  }
+  button {
+    background-color: #f9f9f9;
+  }
+}

examples/react-istanbul-coverage/src/main.jsx

@@ -0,0 +1,10 @@
+import React from 'react'
+import ReactDOM from 'react-dom/client'
+import App from './App'
+import './index.css'
+
+ReactDOM.createRoot(document.getElementById('root')).render(
+  <React.StrictMode>
+    <App />
+  </React.StrictMode>
+)

examples/react-istanbul-coverage/vite.config.js

@@ -0,0 +1,14 @@
+import { defineConfig } from 'vitest/config'
+import react from '@vitejs/plugin-react'
+
+// https://vitejs.dev/config/
+export default defineConfig({
+  plugins: [react()],
+  test: {
+    coverage: {
+      provider: 'istanbul',
+      watchAll: false,
+    },
+    environment: 'jsdom',
+  },
+})

packages/coverage-istanbul/src/provider.ts

@@ -105,6 +105,11 @@ export class IstanbulCoverageProvider implements CoverageProvider {
       return map
     }, {})
 
+    if (!this.ctx.isFirstRun && !this.ctx.config.coverage.watchAll && this.ctx.changedTests.size > 0) {
+      const changedTests = Array.from(this.ctx.changedTests)
+      mergedCoverage.filter(key => key === changedTests[0].replace('.test', ''))
+    }
+
     if (this.options.all)
       await this.includeUntestedFiles(mergedCoverage)
 

packages/vitest/src/defaults.ts

@@ -37,6 +37,7 @@ const coverageConfigDefaults = {
   // default extensions used by c8, plus '.vue' and '.svelte'
   // see https://github.com/istanbuljs/schema/blob/master/default-extension.js
   extension: ['.js', '.cjs', '.mjs', '.ts', '.tsx', '.jsx', '.vue', '.svelte'],
+  watchAll: true,
 } as ResolvedCoverageOptions
 
 export const fakeTimersDefaults = {

packages/vitest/src/node/core.ts

@@ -419,7 +419,6 @@ export class Vitest {
 
       this.snapshot.clear()
       const files = Array.from(this.changedTests)
-      this.changedTests.clear()
 
       if (this.coverageProvider && this.config.coverage.cleanOnRerun)
         await this.coverageProvider.clean()
@@ -429,6 +428,7 @@ export class Vitest {
       await this.runFiles(files)
 
       await this.coverageProvider?.reportCoverage()
+      this.changedTests.clear()
 
       if (!this.config.browser)
         await this.report('onWatcherStart')

packages/vitest/src/types/coverage.ts

@@ -142,6 +142,12 @@ export interface BaseCoverageOptions {
    * Whether to include all files, including the untested ones into report
    */
   all?: boolean
+  /**
+   * Runs coverage for all files. If 'false', only for the changed file.
+   *
+   * @default true
+   */
+  watchAll?: boolean
 }
 
 export interface CoverageIstanbulOptions extends BaseCoverageOptions {