From b181b8aaf3d91302e4fcaaea6f5979499d50ee54 Mon Sep 17 00:00:00 2001
From: VonRehberg <vonrehberg88@gmail.com>
Date: Mon, 12 Aug 2024 15:57:40 +0200
Subject: [PATCH] fix(ts-jest): fixed nullable mocks issue (#759)

closes #757

Co-authored-by: Christian Jeschke <cjeschke@vonrehberg.consulting>
---
 packages/testing/ts-jest/src/mocks.spec.ts | 16 ++++++++++++++++
 packages/testing/ts-jest/src/mocks.ts      |  2 +-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/packages/testing/ts-jest/src/mocks.spec.ts b/packages/testing/ts-jest/src/mocks.spec.ts
index 682bade0c..3759a315a 100644
--- a/packages/testing/ts-jest/src/mocks.spec.ts
+++ b/packages/testing/ts-jest/src/mocks.spec.ts
@@ -157,6 +157,22 @@ describe('Mocks', () => {
 
       expect(test.base).toEqual(base);
     });
+
+    it('should accept mocks returning nullables', async () => {
+      interface Test {
+        foo(): number | undefined;
+      }
+
+      const mock = createMock<Test>();
+      mock.foo.mockImplementation(() => {
+        return 0;
+      });
+      expect(mock.foo()).toEqual(0);
+      mock.foo.mockImplementation(() => {
+        return undefined;
+      });
+      expect(mock.foo()).toEqual(undefined);
+    });
   });
 
   describe('auto mocked', () => {
diff --git a/packages/testing/ts-jest/src/mocks.ts b/packages/testing/ts-jest/src/mocks.ts
index 36f1001b7..99c1d22c2 100644
--- a/packages/testing/ts-jest/src/mocks.ts
+++ b/packages/testing/ts-jest/src/mocks.ts
@@ -30,7 +30,7 @@ const createRecursiveMockProxy = (name: string) => {
   return new Proxy(t, {
     apply: (target, thisArg, argsArray) => {
       const result = Reflect.apply(target, thisArg, argsArray);
-      if (result) {
+      if (target.getMockImplementation() || result) {
         return result;
       } else {
         if (!cache.has('__apply')) {