feat(coverage-istanbul): add "all" option

- Similar as nyc and c8 has

docs/config/index.md

@@ -532,6 +532,13 @@ Set to array of class method names to ignore for coverage.
 
 Watermarks for statements, lines, branches and functions.
 
+##### all
+
+- **Type:** `boolean`
+- **Default:** false
+
+Whether to include all files, including the untested ones into report.
+
 ### testNamePattern
 
 - **Type** `string | RegExp`

packages/coverage-istanbul/src/provider.ts

@@ -23,7 +23,10 @@ interface TestExclude {
     exclude?: string | string[]
     extension?: string | string[]
     excludeNodeModules?: boolean
-  }): { shouldInstrument(filePath: string): boolean }
+  }): {
+    shouldInstrument(filePath: string): boolean
+    glob(cwd: string): Promise<string[]>
+  }
 }
 
 export class IstanbulCoverageProvider implements CoverageProvider {
@@ -95,12 +98,15 @@ export class IstanbulCoverageProvider implements CoverageProvider {
   }
 
   async reportCoverage() {
-    const mergedCoverage = this.coverages.reduce((coverage, previousCoverageMap) => {
+    const mergedCoverage: CoverageMap = this.coverages.reduce((coverage, previousCoverageMap) => {
       const map = libCoverage.createCoverageMap(coverage)
       map.merge(previousCoverageMap)
       return map
     }, {})
 
+    if (this.options.all)
+      await this.includeUntestedFiles(mergedCoverage)
+
     const sourceMapStore = libSourceMaps.createSourceMapStore()
     const coverageMap: CoverageMap = await sourceMapStore.transformCoverage(mergedCoverage)
 
@@ -175,6 +181,39 @@ export class IstanbulCoverageProvider implements CoverageProvider {
       }
     }
   }
+
+  async includeUntestedFiles(coverageMap: CoverageMap) {
+    // Load, instrument and collect empty coverages from all files which
+    // are not already in the coverage map
+    const includedFiles = await this.testExclude.glob(this.ctx.config.root)
+    const uncoveredFiles = includedFiles
+      .map(file => resolve(this.ctx.config.root, file))
+      .filter(file => !coverageMap.data[file])
+
+    const transformResults = await Promise.all(uncoveredFiles.map(async (filename) => {
+      const transformResult = await this.ctx.vitenode.transformRequest(filename)
+      return { transformResult, filename }
+    }))
+
+    for (const { transformResult, filename } of transformResults) {
+      const sourceMap = transformResult?.map
+
+      if (sourceMap) {
+        this.instrumenter.instrumentSync(
+          transformResult.code,
+          filename,
+          {
+            ...sourceMap,
+            version: sourceMap.version.toString(),
+          },
+        )
+
+        const lastCoverage = this.instrumenter.lastFileCoverage()
+        if (lastCoverage)
+          coverageMap.data[lastCoverage.path] = lastCoverage
+      }
+    }
+  }
 }
 
 function resolveIstanbulOptions(options: CoverageIstanbulOptions, root: string) {

packages/vitest/src/types/coverage.ts

@@ -137,6 +137,11 @@ export interface BaseCoverageOptions {
    * Extensions for files to be included in coverage
    */
   extension?: string | string[]
+
+  /**
+   * Whether to include all files, including the untested ones into report
+   */
+  all?: boolean
 }
 
 export interface CoverageIstanbulOptions extends BaseCoverageOptions {
@@ -166,7 +171,6 @@ export interface CoverageC8Options extends BaseCoverageOptions {
    */
   excludeNodeModules?: boolean
 
-  all?: boolean
   src?: string[]
 
   100?: boolean

test/coverage-test/coverage-test/coverage.istanbul.test.ts

@@ -3,7 +3,7 @@ import { resolve } from 'pathe'
 import { expect, test } from 'vitest'
 
 test('istanbul html report', async () => {
-  const coveragePath = resolve('./coverage')
+  const coveragePath = resolve('./coverage/coverage-test/src')
   const files = fs.readdirSync(coveragePath)
 
   expect(files).toContain('index.html')
@@ -22,3 +22,10 @@ test('istanbul lcov report', async () => {
 
   expect(lcovReportFiles).toContain('index.html')
 })
+
+test('all includes untested files', () => {
+  const coveragePath = resolve('./coverage/coverage-test/src')
+  const files = fs.readdirSync(coveragePath)
+
+  expect(files).toContain('untested-file.ts.html')
+})

test/coverage-test/src/untested-file.ts

@@ -0,0 +1,3 @@
+export default function untestedFile() {
+  return 'This file should end up in report when {"all": true} is given'
+}

test/coverage-test/vitest.config.ts

@@ -19,6 +19,7 @@ export default defineConfig({
     coverage: {
       enabled: true,
       clean: true,
+      all: true,
       reporter: ['html', 'text', 'lcov'],
     },
   },