fix: fix vi.mock({ spy: true }) node v8 coverage

packages/vitest/src/runtime/moduleRunner/moduleEvaluator.ts

@@ -315,7 +315,8 @@ export class VitestModuleEvaluator implements ModuleEvaluator {
     )})=>{{`
     const wrappedCode = `${codeDefinition}${code}\n}}`
     const options = {
-      filename: module.id,
+      // use original id for auto spy module (vi.mock(..., { spy: true }))
+      filename: module.id.startsWith('mock:') ? module.id.slice(5) : module.id,
       lineOffset: 0,
       columnOffset: -codeDefinition.length,
     }

test/coverage-test/fixtures/src/mock-target.ts

@@ -0,0 +1,7 @@
+export function double(value: number): number {
+  return value * 2
+}
+
+export function triple(value: number): number {
+  return value * 3
+}

test/coverage-test/fixtures/test/mock-autospy-fixture.test.ts

@@ -0,0 +1,10 @@
+import { expect, test, vi } from 'vitest'
+import { double, triple } from '../src/mock-target'
+
+vi.mock(import('../src/mock-target'), { spy: true })
+
+test('autospy calls original and can be spied on', () => {
+  expect(double(5)).toBe(10)
+  expect(double).toHaveBeenCalledWith(5)
+  expect(triple).not.toHaveBeenCalled()
+})

test/coverage-test/fixtures/test/mock-importActual-fixture.test.ts

@@ -0,0 +1,17 @@
+import { expect, test, vi } from 'vitest'
+import { double, triple } from '../src/mock-target'
+
+// Manual spy approach using importOriginal callback - this collects coverage
+vi.mock(import('../src/mock-target'), async (importOriginal) => {
+  const actual = await importOriginal()
+  return {
+    double: vi.fn(actual.double),
+    triple: vi.fn(actual.triple),
+  }
+})
+
+test('importActual calls original and can be spied on', () => {
+  expect(double(5)).toBe(10)
+  expect(double).toHaveBeenCalledWith(5)
+  expect(triple).not.toHaveBeenCalled()
+})

test/coverage-test/test/mock-autospy.test.ts

@@ -0,0 +1,40 @@
+import { expect } from 'vitest'
+import { readCoverageMap, runVitest, test } from '../utils'
+
+test('vi.mock({ spy: true }) collects coverage of original module', async () => {
+  await runVitest({
+    include: ['fixtures/test/mock-autospy-fixture.test.ts'],
+    coverage: {
+      reporter: 'json',
+      include: ['fixtures/src/mock-target.ts'],
+    },
+  })
+
+  const coverageMap = await readCoverageMap()
+  expect(coverageMap).toMatchInlineSnapshot(`
+    {
+      "branches": "0/0 (100%)",
+      "functions": "1/2 (50%)",
+      "lines": "1/2 (50%)",
+      "statements": "1/2 (50%)",
+    }
+  `)
+
+  const coverage = coverageMap.fileCoverageFor('<process-cwd>/fixtures/src/mock-target.ts')
+  const functionCoverage = Object.keys(coverage.fnMap)
+    .map(index => ({ name: coverage.fnMap[index].name, hits: coverage.f[index] }))
+    .sort((a, b) => a.name.localeCompare(b.name))
+
+  expect(functionCoverage).toMatchInlineSnapshot(`
+    [
+      {
+        "hits": 1,
+        "name": "double",
+      },
+      {
+        "hits": 0,
+        "name": "triple",
+      },
+    ]
+  `)
+})