LibJS: Don't coerce this value to object in Promise.prototype.finally()

1 files changed, 8 insertions, 0 deletions

diff --git a/Userland/Libraries/LibJS/Tests/builtins/Promise/Promise.prototype.finally.js b/Userland/Libraries/LibJS/Tests/builtins/Promise/Promise.prototype.finally.js
index cdb7a09029..a062b44590 100644
--- a/Userland/Libraries/LibJS/Tests/builtins/Promise/Promise.prototype.finally.js
+++ b/Userland/Libraries/LibJS/Tests/builtins/Promise/Promise.prototype.finally.js
@@ -52,3 +52,11 @@ describe("normal behavior", () => {
         expect(thenFinallyArg).not.toBe(catchFinallyArg);
     });
 });
+
+describe("errors", () => {
+    test("this value must be an object", () => {
+        expect(() => {
+            Promise.prototype.finally.call("foo");
+        }).toThrowWithMessage(TypeError, "foo is not an object");
+    });
+});