docs: istanbul coverage provider

docs/config/index.md

@@ -404,10 +404,39 @@ Isolate environment for each test file. Does not work if you disable [`--threads
 
 ### coverage
 
-- **Type:** `C8Options`
+- **Type:** `C8Options | IstanbulOptions`
 - **Default:** `undefined`
 
-Coverage options passed to [C8](https://github.com/bcoe/c8).
+You can use [`c8`](https://github.com/bcoe/c8) or [`istanbul`](https://istanbul.js.org/) for coverage collection.
+
+#### provider
+
+- **Type:** `c8 | istanbul`
+- **Default:** `c8`
+
+Use `provider` to select the tool for coverage collection.
+
+#### C8Options
+
+Used when `provider: 'c8'` is set. Coverage options passed to [`c8`](https://github.com/bcoe/c8).
+
+#### IstanbulOptions
+
+Used when `provider: 'istanbl'` is set.
+
+##### ignoreClassMethods
+
+- **Type:** `string[]`
+- **Default** []
+
+Set to array of class method names to ignore for coverage.
+
+##### watermarks
+
+- **Type:** `{ statements?: [number, number], functions?: [number, number], branches?: [number, number], lines?: [number, number]`
+- **Default** `{ statements: [50, 80], functions: [50, 80], branches: [50, 80], lines: [50, 80] }`
+
+Watermarks for statements, lines, branches and functions.
 
 ### testNamePattern
 

docs/guide/coverage.md

@@ -4,10 +4,16 @@ title: Coverage | Guide
 
 # Coverage
 
-Vitest supports Native code coverage via [`c8`](https://github.com/bcoe/c8). `c8` is an optional peer dependency, to use the coverage feature you will need to install it first by:
+Vitest supports Native code coverage via [`c8`](https://github.com/bcoe/c8) and instrumented code coverage via [`istanbul`](https://istanbul.js.org/).
+
+`c8` and `istanbul`-packages are optional peer dependencies, to use the coverage feature you will need to install these first by:
 
 ```bash
+# For c8
 npm i -D c8
+
+# For istanbul, TODO: replace with `@vitest/coverage-istanbul` or similar package
+npm i -D istanbul-lib-coverage istanbul-lib-instrument istanbul-lib-report istanbul-lib-source-maps istanbul-reports
 ```
 
 Then you could get the coverage by passing the `--coverage` flag in CLI.
@@ -35,3 +41,18 @@ export default defineConfig({
   },
 })
 ```
+
+You can select the coverage tool by setting `test.coverage.provider` to either `c8` or `istanbul`:
+
+```ts
+// vite.config.ts
+import { defineConfig } from 'vitest/config'
+
+export default defineConfig({
+  test: {
+    coverage: {
+      provider: 'istanbul',
+    },
+  },
+})
+```