From dfd4b01a976fcdb093af64eec947d19becf9f4cc Mon Sep 17 00:00:00 2001
From: Hanaasagi <ambiguous404@gmail.com>
Date: Thu, 7 Dec 2023 16:41:31 +0800
Subject: [PATCH] fix(jest): fix segfault when passing jest.fn into another
 jest.fn (#7507)

Close: #5900
---
 src/bun.js/bindings/JSMockFunction.cpp |  2 ++
 test/js/bun/test/mock-fn.test.js       | 15 +++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/src/bun.js/bindings/JSMockFunction.cpp b/src/bun.js/bindings/JSMockFunction.cpp
index e9c9c1f1e1..40a8c97b31 100644
--- a/src/bun.js/bindings/JSMockFunction.cpp
+++ b/src/bun.js/bindings/JSMockFunction.cpp
@@ -280,6 +280,8 @@ public:
             if (lengthJSValue.isNumber()) {
                 this->putDirect(vm, vm.propertyNames->length, (lengthJSValue), JSC::PropertyAttribute::DontEnum | JSC::PropertyAttribute::ReadOnly);
             }
+        } else if (auto* fn = jsDynamicCast<JSMockFunction*>(value)) {
+            nameToUse = fn->get(global, vm.propertyNames->name).toWTFString(global);
         } else if (auto* fn = jsDynamicCast<InternalFunction*>(value)) {
             nameToUse = fn->name();
         } else {
diff --git a/test/js/bun/test/mock-fn.test.js b/test/js/bun/test/mock-fn.test.js
index cb9e1140a1..6a700eb385 100644
--- a/test/js/bun/test/mock-fn.test.js
+++ b/test/js/bun/test/mock-fn.test.js
@@ -620,6 +620,21 @@ describe("mock()", () => {
     expect(fn).toHaveBeenNthCalledWith(5, 1, undefined);
     expect(fn).not.toHaveBeenNthCalledWith(5, 1);
   });
+
+  it("no segmentation fault when passing jest.fn into another jest.fn, issue#5900", () => {
+    function foo() {
+      return true;
+    }
+
+    function bar(fn = jest.fn(foo)) {
+      expect(fn.getMockName()).toBe("foo");
+      let newFn = jest.fn(fn);
+      expect(newFn.getMockName()).toBe("foo");
+      return newFn;
+    }
+
+    expect(bar()()).toBe(true);
+  });
 });
 
 describe("spyOn", () => {