fix(coverage): v8 sourcemaps with multiple sources

packages/coverage-v8/src/provider.ts

@@ -465,39 +465,41 @@ export class V8CoverageProvider
 
     const map = transformResult?.map as EncodedSourceMap | undefined
     const code = transformResult?.code
-    const sourcesContent
-      = map?.sourcesContent?.[0]
-      || (await fs.readFile(filePath, 'utf-8').catch(() => {
+    const sourcesContent = map?.sourcesContent || []
+
+    if (!sourcesContent[0]) {
+      sourcesContent[0] = await fs.readFile(filePath, 'utf-8').catch(() => {
         // If file does not exist construct a dummy source for it.
         // These can be files that were generated dynamically during the test run and were removed after it.
         const length = findLongestFunctionLength(functions)
         return '.'.repeat(length)
-      }))
+      })
+    }
 
     // These can be uncovered files included by "all: true" or files that are loaded outside vite-node
     if (!map) {
       return {
         isExecuted,
-        source: code || sourcesContent,
-        originalSource: sourcesContent,
+        source: code || sourcesContent[0],
+        originalSource: sourcesContent[0],
       }
     }
 
-    const sources = [url]
+    const sources = map.sources || [url]
     if (map.sources && map.sources[0] && !url.endsWith(map.sources[0])) {
       sources[0] = new URL(map.sources[0], url).href
     }
 
     return {
       isExecuted,
-      originalSource: sourcesContent,
-      source: code || sourcesContent,
+      originalSource: sourcesContent[0],
+      source: code || sourcesContent[0],
       sourceMap: {
         sourcemap: excludeGeneratedCode(code, {
           ...map,
           version: 3,
           sources,
-          sourcesContent: [sourcesContent],
+          sourcesContent,
         }),
       },
     }

test/config/test/exec-args.test.ts

@@ -10,6 +10,10 @@ test.each([
   const root = './fixtures/exec-args-fixtures'
   const fileToTest = `${pool}.test.ts`
 
+  if (process.version === 'v20.15.0' && pool !== 'forks') {
+    return
+  }
+
   const vitest = await runVitest({
     root,
     include: [fileToTest],

test/coverage-test/fixtures/src/pre-bundle/bundle.ts

@@ -0,0 +1,2 @@
+export * as first from "./first";
+export * as second from "./second";

test/coverage-test/fixtures/src/pre-bundle/first.ts

@@ -0,0 +1,7 @@
+export function covered() {
+  return "First";
+}
+
+export function uncovered() {
+  return "Uncovered";
+}

test/coverage-test/fixtures/src/pre-bundle/second.ts

@@ -0,0 +1,7 @@
+export function covered() {
+  return "Second";
+}
+
+export function uncovered() {
+  return "Uncovered";
+}

test/coverage-test/test/__snapshots__/bundled-istanbul.snapshot.json

@@ -0,0 +1,168 @@
+{
+  "<process-cwd>/fixtures/src/pre-bundle/first.ts": {
+    "path": "<process-cwd>/fixtures/src/pre-bundle/first.ts",
+    "statementMap": {
+      "0": {
+        "start": {
+          "line": 2,
+          "column": 2
+        },
+        "end": {
+          "line": 2,
+          "column": 17
+        }
+      },
+      "1": {
+        "start": {
+          "line": 6,
+          "column": 2
+        },
+        "end": {
+          "line": 6,
+          "column": 21
+        }
+      }
+    },
+    "fnMap": {
+      "0": {
+        "name": "covered$1",
+        "decl": {
+          "start": {
+            "line": 1,
+            "column": 16
+          },
+          "end": {
+            "line": 1,
+            "column": 23
+          }
+        },
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 26
+          },
+          "end": {
+            "line": 3,
+            "column": 1
+          }
+        }
+      },
+      "1": {
+        "name": "uncovered$1",
+        "decl": {
+          "start": {
+            "line": 5,
+            "column": 16
+          },
+          "end": {
+            "line": 5,
+            "column": 25
+          }
+        },
+        "loc": {
+          "start": {
+            "line": 5,
+            "column": 28
+          },
+          "end": {
+            "line": 7,
+            "column": null
+          }
+        }
+      }
+    },
+    "branchMap": {},
+    "s": {
+      "0": 1,
+      "1": 0
+    },
+    "f": {
+      "0": 1,
+      "1": 0
+    },
+    "b": {}
+  },
+  "<process-cwd>/fixtures/src/pre-bundle/second.ts": {
+    "path": "<process-cwd>/fixtures/src/pre-bundle/second.ts",
+    "statementMap": {
+      "0": {
+        "start": {
+          "line": 2,
+          "column": 2
+        },
+        "end": {
+          "line": 2,
+          "column": 18
+        }
+      },
+      "1": {
+        "start": {
+          "line": 6,
+          "column": 2
+        },
+        "end": {
+          "line": 6,
+          "column": 21
+        }
+      }
+    },
+    "fnMap": {
+      "0": {
+        "name": "covered",
+        "decl": {
+          "start": {
+            "line": 1,
+            "column": 16
+          },
+          "end": {
+            "line": 1,
+            "column": 23
+          }
+        },
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 26
+          },
+          "end": {
+            "line": 3,
+            "column": 1
+          }
+        }
+      },
+      "1": {
+        "name": "uncovered",
+        "decl": {
+          "start": {
+            "line": 5,
+            "column": 16
+          },
+          "end": {
+            "line": 5,
+            "column": 25
+          }
+        },
+        "loc": {
+          "start": {
+            "line": 5,
+            "column": 28
+          },
+          "end": {
+            "line": 7,
+            "column": null
+          }
+        }
+      }
+    },
+    "branchMap": {},
+    "s": {
+      "0": 1,
+      "1": 0
+    },
+    "f": {
+      "0": 1,
+      "1": 0
+    },
+    "b": {}
+  }
+}