fix(coverage): c8 to ignore vite's generated helpers

packages/coverage-c8/src/provider.ts

@@ -169,7 +169,7 @@ export class C8CoverageProvider extends BaseCoverageProvider implements Coverage
 
       return {
         sourceMap: {
-          sourcemap: data.map,
+          sourcemap: removeViteHelpersFromSourceMaps(data.source, data.map),
         },
         source: Array(offset).fill('.').join('') + data.source,
       }
@@ -193,3 +193,27 @@ export class C8CoverageProvider extends BaseCoverageProvider implements Coverage
     }
   }
 }
+
+function removeViteHelpersFromSourceMaps(source: string | undefined, map: EncodedSourceMap): EncodedSourceMap {
+  if (!source?.includes('__vite_ssr_exports__'))
+    return map
+
+  const exportIndexes = source.split('\n').map((line, index) => {
+    if (/Object\.defineProperty\(__vite_ssr_exports__/.test(line))
+      return index
+    return -1
+  }).filter(index => index !== -1)
+
+  if (exportIndexes.length === 0)
+    return map
+
+  const mappings = map.mappings.split(';')
+  exportIndexes.forEach((index) => {
+    mappings[index] = ''
+  })
+
+  return {
+    ...map,
+    mappings: mappings.join(';'),
+  }
+}