fix(coverage): consistent type-only file handling (#6183)

Author: AriPerkkio

packages/coverage-v8/package.json

@@ -54,7 +54,6 @@
     "magic-string": "^0.30.10",
     "magicast": "^0.3.4",
     "std-env": "^3.7.0",
-    "strip-literal": "^2.1.0",
     "test-exclude": "^7.0.1",
     "tinyrainbow": "^1.2.0"
   },

packages/coverage-v8/src/provider.ts

@@ -19,7 +19,6 @@ import remapping from '@ampproject/remapping'
 import { normalize, resolve } from 'pathe'
 import c from 'tinyrainbow'
 import { provider } from 'std-env'
-import { stripLiteral } from 'strip-literal'
 import createDebug from 'debug'
 import { cleanUrl } from 'vite-node/utils'
 import type { EncodedSourceMap, FetchResult } from 'vite-node'
@@ -391,16 +390,11 @@ export class V8CoverageProvider extends BaseCoverageProvider implements Coverage
 
       const coverages = await Promise.all(
         chunk.map(async (filename) => {
-          const { originalSource, source } = await this.getSources(
+          const { originalSource } = await this.getSources(
             filename.href,
             transformResults,
           )
 
-          // Ignore empty files, e.g. files that contain only typescript types and no runtime code
-          if (source && stripLiteral(source).trim() === '') {
-            return null
-          }
-
           const coverage = {
             url: filename.href,
             scriptId: '0',

pnpm-lock.yaml

@@ -12,7 +12,6 @@ type LineCoverage = Record<number, CoveredLine | UncoveredLine | IgnoredLine>
 describe('include empty lines', () => {
   let coveredFileLines: LineCoverage
   let uncoveredFileLines: LineCoverage
-  let files: string[]
 
   beforeAll(async () => {
     await runVitest({
@@ -28,16 +27,7 @@ describe('include empty lines', () => {
       },
     })
 
-    ;({ coveredFileLines, uncoveredFileLines, files } = await readCoverage())
-  })
-
-  test('file containing only types is ignored', () => {
-    expect(files).toMatchInlineSnapshot(`
-      [
-        "<process-cwd>/fixtures/src/empty-lines.ts",
-        "<process-cwd>/fixtures/src/untested-file.ts",
-      ]
-    `)
+    ;({ coveredFileLines, uncoveredFileLines } = await readCoverage())
   })
 
   test('lines are included', async () => {
@@ -64,7 +54,7 @@ describe('include empty lines', () => {
 describe('ignore empty lines', () => {
   let coveredFileLines: LineCoverage
   let uncoveredFileLines: LineCoverage
-  let files: string[]
+  let typesOnlyFileLines: LineCoverage
 
   beforeAll(async () => {
     await runVitest({
@@ -79,16 +69,13 @@ describe('ignore empty lines', () => {
       },
     })
 
-    ;({ coveredFileLines, uncoveredFileLines, files } = await readCoverage())
+    ;({ coveredFileLines, uncoveredFileLines, typesOnlyFileLines } = await readCoverage())
   })
 
-  test('file containing only types is ignored', () => {
-    expect(files).toMatchInlineSnapshot(`
-      [
-        "<process-cwd>/fixtures/src/empty-lines.ts",
-        "<process-cwd>/fixtures/src/untested-file.ts",
-      ]
-    `)
+  test('file containing only types has no uncovered lines', () => {
+    expect(typesOnlyFileLines[1]).toBe(undefined)
+    expect(typesOnlyFileLines[2]).toBe(undefined)
+    expect(typesOnlyFileLines[3]).toBe(undefined)
   })
 
   test('empty lines are ignored', async () => {
@@ -184,12 +171,12 @@ coverageTest('cover some lines', () => {
 
 async function readCoverage() {
   const coverageMap = await readCoverageMap()
-  const files = coverageMap.files()
 
   const coveredFileLines = coverageMap.fileCoverageFor('<process-cwd>/fixtures/src/empty-lines.ts').getLineCoverage() as LineCoverage
   const uncoveredFileLines = coverageMap.fileCoverageFor('<process-cwd>/fixtures/src/untested-file.ts').getLineCoverage() as LineCoverage
+  const typesOnlyFileLines = coverageMap.fileCoverageFor('<process-cwd>/fixtures/src/types-only.ts').getLineCoverage() as LineCoverage
 
-  return { coveredFileLines, uncoveredFileLines, files }
+  return { coveredFileLines, uncoveredFileLines, typesOnlyFileLines }
 }
 
 function range(count: number, options: { base: number } = { base: 1 }) {