From f379b36e6174848d769b9344a2b0fe23d005dd42 Mon Sep 17 00:00:00 2001
From: Giles Roadnight <10414642+Roaders@users.noreply.github.com>
Date: Thu, 19 May 2022 11:03:22 +0100
Subject: [PATCH] Fix toString bug

---
 main/mock/operators.ts        | 10 +++++++---
 spec/mock/mock-static.spec.ts | 13 +++++++++++++
 spec/mock/mock.spec.ts        |  7 +++++++
 3 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/main/mock/operators.ts b/main/mock/operators.ts
index 928ae91..6446e5c 100644
--- a/main/mock/operators.ts
+++ b/main/mock/operators.ts
@@ -43,7 +43,10 @@ export function setupFunction<T, C extends ConstructorFunction<T>, U extends Fun
             mocked.functionReplacementLookup['function'] || {});
         functionLookup[functionName as string] = mockFunction;
 
-        if (mocked.mock[functionName] == null) {
+        // we do not replace an existing function in case it has already been destructured and sut already has a reference to it
+        // we do replace the mocked implementation above though
+        // eslint-disable-next-line @typescript-eslint/ban-types
+        if ((mocked.mock[functionName] as Function)?.name != functionReplacement.name) {
             mocked.mock[functionName] = functionReplacement as any;
         }
         mocked.functionCallLookup[functionName] = [];
@@ -53,7 +56,7 @@ export function setupFunction<T, C extends ConstructorFunction<T>, U extends Fun
 }
 
 /**
- * Mocks a staticfunction on an existing Mock.
+ * Mocks a static function on an existing Mock.
  * Allows function call verification to be performed later in the test.
  * You can optionally set a mock function implementation that will be called.
  *
@@ -83,7 +86,8 @@ export function setupStaticFunction<
             mocked.functionReplacementLookup['staticFunction'] || {});
         staticFunctionLookup[functionName as string] = mockFunction;
 
-        if (mocked.mockConstructor[functionName] == null) {
+        // eslint-disable-next-line @typescript-eslint/ban-types
+        if ((mocked.mockConstructor[functionName] as Function)?.name != functionReplacement.name) {
             mocked.mockConstructor[functionName] = functionReplacement as any;
         }
         mocked.staticFunctionCallLookup[functionName] = [];
diff --git a/spec/mock/mock-static.spec.ts b/spec/mock/mock-static.spec.ts
index da88e43..6a94a28 100644
--- a/spec/mock/mock-static.spec.ts
+++ b/spec/mock/mock-static.spec.ts
@@ -1445,6 +1445,15 @@ describe('mock with statics', () => {
             expect(newMock.mockConstructor.functionWithParamsAndNoReturn('', 123, true)).toBeUndefined();
             expect(newMock.mockConstructor.functionWithParamsAndReturn('')).toBeUndefined();
         });
+
+        it(`should work with predefined function toString`, () => {
+            const mockedValue = 'mocked toString return value';
+            const toStringMock = Mock.create<SampleMockedClass, typeof SampleMockedClass>().setup(
+                setupStaticFunction('toString', () => mockedValue),
+            );
+
+            expect(toStringMock.mockConstructor.toString()).toEqual(mockedValue);
+        });
     });
 });
 
@@ -1456,6 +1465,10 @@ class SampleMockedClass {
 
     constructor(_paramsOne: {}, _paramTwo: Date) {}
 
+    public static toString(): string {
+        return 'original toString';
+    }
+
     public static functionWithNoParamsAndNoReturn(): void {}
 
     public functionWithNoParamsAndNoReturn(): void {}
diff --git a/spec/mock/mock.spec.ts b/spec/mock/mock.spec.ts
index 1a1290d..a2d4a39 100644
--- a/spec/mock/mock.spec.ts
+++ b/spec/mock/mock.spec.ts
@@ -1653,6 +1653,13 @@ describe('mock', () => {
             expect(newMock.functionWithParamsAndNoReturn('', 123, true)).toBeUndefined();
             expect(newMock.functionWithParamsAndReturn('')).toBeUndefined();
         });
+
+        it(`should work with predefined function toString`, () => {
+            const mockedValue = 'mocked toString return value';
+            const toStringMock = Mock.create<Buffer>().setup(setupFunction('toString', () => mockedValue));
+
+            expect(toStringMock.mock.toString()).toEqual(mockedValue);
+        });
     });
 
     describe('parameter comparison', () => {