From 2c3a910f60cf9a38565bf249b7fa2dd146e0c9d2 Mon Sep 17 00:00:00 2001
From: AriPerkkio <ari.perkkio@gmail.com>
Date: Sun, 3 Mar 2024 20:05:30 +0200
Subject: [PATCH] fix(coverage): v8 to ignore type-only files

---
 packages/coverage-v8/package.json    |  1 +
 packages/coverage-v8/src/provider.ts | 26 ++++++++++++++++++++------
 pnpm-lock.yaml                       |  3 +++
 test/coverage-test/src/types.ts      |  3 +++
 4 files changed, 27 insertions(+), 6 deletions(-)
 create mode 100644 test/coverage-test/src/types.ts

diff --git a/packages/coverage-v8/package.json b/packages/coverage-v8/package.json
index 569920243152..d01b01765276 100644
--- a/packages/coverage-v8/package.json
+++ b/packages/coverage-v8/package.json
@@ -55,6 +55,7 @@
     "magicast": "^0.3.3",
     "picocolors": "^1.0.0",
     "std-env": "^3.5.0",
+    "strip-literal": "^2.0.0",
     "test-exclude": "^6.0.0",
     "v8-to-istanbul": "^9.2.0"
   },
diff --git a/packages/coverage-v8/src/provider.ts b/packages/coverage-v8/src/provider.ts
index 517f446618cb..2f52cf8bf386 100644
--- a/packages/coverage-v8/src/provider.ts
+++ b/packages/coverage-v8/src/provider.ts
@@ -14,6 +14,7 @@ import remapping from '@ampproject/remapping'
 import { normalize, resolve } from 'pathe'
 import c from 'picocolors'
 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'
@@ -260,7 +261,13 @@ export class V8CoverageProvider extends BaseCoverageProvider implements Coverage
       }
 
       const coverages = await Promise.all(chunk.map(async (filename) => {
-        const { source } = await this.getSources(filename.href, transformResults)
+        const transformResult = await this.ctx.vitenode.transformRequest(filename.pathname).catch(() => {})
+
+        // Ignore empty files, e.g. files that contain only typescript types and no runtime code
+        if (transformResult && stripLiteral(transformResult.code).trim() === '')
+          return null
+
+        const { originalSource } = await this.getSources(filename.href, transformResults)
 
         const coverage = {
           url: filename.href,
@@ -269,7 +276,7 @@ export class V8CoverageProvider extends BaseCoverageProvider implements Coverage
           functions: [{
             ranges: [{
               startOffset: 0,
-              endOffset: source.length,
+              endOffset: originalSource.length,
               count: 0,
             }],
             isBlockCoverage: true,
@@ -281,7 +288,10 @@ export class V8CoverageProvider extends BaseCoverageProvider implements Coverage
         return { result: [coverage] }
       }))
 
-      merged = mergeProcessCovs([merged, ...coverages])
+      merged = mergeProcessCovs([
+        merged,
+        ...coverages.filter((cov): cov is NonNullable<typeof cov> => cov != null),
+      ])
     }
 
     return merged
@@ -289,7 +299,7 @@ export class V8CoverageProvider extends BaseCoverageProvider implements Coverage
 
   private async getSources(url: string, transformResults: TransformResults, functions: Profiler.FunctionCoverage[] = []): Promise<{
     source: string
-    originalSource?: string
+    originalSource: string
     sourceMap?: { sourcemap: EncodedSourceMap }
   }> {
     const filePath = normalize(fileURLToPath(url))
@@ -306,8 +316,12 @@ export class V8CoverageProvider extends BaseCoverageProvider implements Coverage
     })
 
     // These can be uncovered files included by "all: true" or files that are loaded outside vite-node
-    if (!map)
-      return { source: code || sourcesContent }
+    if (!map) {
+      return {
+        source: code || sourcesContent,
+        originalSource: sourcesContent,
+      }
+    }
 
     return {
       originalSource: sourcesContent,
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 2b79c7577f3a..62d5671c7555 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -1054,6 +1054,9 @@ importers:
       std-env:
         specifier: ^3.5.0
         version: 3.5.0
+      strip-literal:
+        specifier: ^2.0.0
+        version: 2.0.0
       test-exclude:
         specifier: ^6.0.0
         version: 6.0.0
diff --git a/test/coverage-test/src/types.ts b/test/coverage-test/src/types.ts
new file mode 100644
index 000000000000..439f557c49cf
--- /dev/null
+++ b/test/coverage-test/src/types.ts
@@ -0,0 +1,3 @@
+export type First = 'This' | 'file' | 'should'
+
+export type Second = 'be' | 'excluded' | 'from' | 'report'