fix(jest-runtime): prevent global module registry from leaking into i…

…solated registry

BREAKING CHANGE:
require statements in isolateModules will always return a fresh instance of imported module

packages/jest-runtime/src/__tests__/runtime_require_module_or_mock.test.js

@@ -218,6 +218,33 @@ describe('resetModules', () => {
 });
 
 describe('isolateModules', () => {
+  it("keeps it's registry isolated from global one", () =>
+    createRuntime(__filename, {
+      moduleNameMapper,
+    }).then(runtime => {
+      let exports;
+      exports = runtime.requireModuleOrMock(
+        runtime.__mockRootPath,
+        'ModuleWithState',
+      );
+      exports.increment();
+      expect(exports.getState()).toBe(2);
+
+      runtime.isolateModules(() => {
+        exports = runtime.requireModuleOrMock(
+          runtime.__mockRootPath,
+          'ModuleWithState',
+        );
+        expect(exports.getState()).toBe(1);
+      });
+
+      exports = runtime.requireModuleOrMock(
+        runtime.__mockRootPath,
+        'ModuleWithState',
+      );
+      expect(exports.getState()).toBe(2);
+    }));
+
   it('resets all modules after the block', () =>
     createRuntime(__filename, {
       moduleNameMapper,

packages/jest-runtime/src/index.ts

@@ -610,13 +610,10 @@ export default class Runtime {
     if (options?.isInternalModule) {
       moduleRegistry = this._internalModuleRegistry;
     } else {
-      if (
-        this._moduleRegistry.get(modulePath) ||
-        !this._isolatedModuleRegistry
-      ) {
-        moduleRegistry = this._moduleRegistry;
-      } else {
+      if (this._isolatedModuleRegistry) {
         moduleRegistry = this._isolatedModuleRegistry;
+      } else {
+        moduleRegistry = this._moduleRegistry;
       }
     }