fix(testing): preserve mock restore export identity

src/testing/module-mock-lifecycle.test.ts

@@ -4,8 +4,9 @@ import { describe, expect, mock, test } from "bun:test"
 import { installModuleMockLifecycle } from "./module-mock-lifecycle"
 
 describe("installModuleMockLifecycle", () => {
-  test("restores the original module exports on mock.restore", () => {
+  test("restores the original module export object instead of a cloned snapshot", () => {
     // given
+    const originalExports = { named: "original" }
     const moduleCalls: Array<{ specifier: string; value: Record<string, unknown> }> = []
     const mockApi = {
       module: (specifier: string, factory: () => Record<string, unknown>) => {
@@ -17,7 +18,7 @@ describe("installModuleMockLifecycle", () => {
     installModuleMockLifecycle(mockApi, {
       getCallerUrl: () => "file:///repo/tests/example.test.ts",
       resolveSpecifier: (specifier) => `resolved:${specifier}`,
-      loadOriginalModule: () => ({ ok: true, value: { named: "original" } }),
+      loadOriginalModule: () => ({ ok: true, value: originalExports }),
     })
 
     // when
@@ -25,13 +26,12 @@ describe("installModuleMockLifecycle", () => {
     mockApi.restore()
 
     // then
-    expect(moduleCalls).toEqual([
-      { specifier: "./dependency", value: { named: "mocked" } },
-      { specifier: "resolved:./dependency", value: { named: "original" } },
-    ])
+    expect(moduleCalls.map((call) => call.specifier)).toEqual(["./dependency", "resolved:./dependency"])
+    const restoreCall = moduleCalls.find((call) => call.specifier === "resolved:./dependency")
+    expect(restoreCall?.value).toBe(originalExports)
   })
 
-  test("restores original exports after the delegate restore runs", () => {
+  test("clears tracked snapshots after the delegate restore runs", () => {
     // given
     const events: string[] = []
     const mockApi = {
@@ -43,7 +43,7 @@ describe("installModuleMockLifecycle", () => {
       }),
     }
 
-    installModuleMockLifecycle(mockApi, {
+    const { restoreModuleMocks } = installModuleMockLifecycle(mockApi, {
       getCallerUrl: () => "file:///repo/tests/example.test.ts",
       resolveSpecifier: (specifier) => `resolved:${specifier}`,
       loadOriginalModule: () => ({ ok: true, value: { named: "original" } }),
@@ -52,6 +52,7 @@ describe("installModuleMockLifecycle", () => {
     // when
     mockApi.module("./dependency", () => ({ named: "mocked" }))
     mockApi.restore()
+    restoreModuleMocks()
 
     // then
     expect(events).toEqual([
@@ -65,7 +66,7 @@ describe("installModuleMockLifecycle", () => {
     // given
     let loadCount = 0
     const mockApi = {
-      module: mock(() => {}),
+      module: mock((_specifier: string, _factory: () => Record<string, unknown>) => {}),
       restore: mock(() => {}),
     }
 

src/testing/module-mock-lifecycle.ts

@@ -31,7 +31,11 @@ function toError(error: unknown): Error {
   return new Error(String(error))
 }
 
-function cloneModuleExports(moduleValue: unknown): Record<string, unknown> {
+function isModuleExports(moduleValue: unknown): moduleValue is Record<string, unknown> {
+  return moduleValue !== null && typeof moduleValue === "object"
+}
+
+function createRestoreExports(moduleValue: unknown): Record<string, unknown> {
   if (typeof moduleValue === "function") {
     const functionExports = Object.assign({}, moduleValue)
     return {
@@ -40,8 +44,8 @@ function cloneModuleExports(moduleValue: unknown): Record<string, unknown> {
     }
   }
 
-  if (moduleValue && typeof moduleValue === "object") {
-    return { ...(moduleValue as Record<string, unknown>) }
+  if (isModuleExports(moduleValue)) {
+    return moduleValue
   }
 
   return { default: moduleValue }
@@ -123,10 +127,10 @@ export function installModuleMockLifecycle(
       const originalModule = loadOriginalModule(specifier, callerUrl)
 
       if (originalModule.ok) {
-        const clonedExports = cloneModuleExports(originalModule.value)
+        const restoreExports = createRestoreExports(originalModule.value)
         snapshots.set(restoreSpecifier, {
           restoreSpecifier,
-          restoreFactory: () => ({ ...clonedExports }),
+          restoreFactory: () => restoreExports,
         })
       }
     }