1 files changed, 53 insertions, 0 deletions
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Function/Function.js b/Userland/Libraries/LibJS/Tests/builtins/Function/Function.js
new file mode 100644
index 0000000000..9a972ab81d
--- /dev/null
+++ b/Userland/Libraries/LibJS/Tests/builtins/Function/Function.js
@@ -0,0 +1,53 @@
+describe("correct behavior", () => {
+    test("constructor properties", () => {
+        expect(Function).toHaveLength(1);
+        expect(Function.name).toBe("Function");
+        expect(Function.prototype).toHaveLength(0);
+        expect(Function.prototype.name).toBe("");
+    });
+
+    test("typeof", () => {
+        expect(typeof Function()).toBe("function");
+        expect(typeof new Function()).toBe("function");
+    });
+
+    test("basic functionality", () => {
+        expect(Function()()).toBeUndefined();
+        expect(new Function()()).toBeUndefined();
+        expect(Function("return 42")()).toBe(42);
+        expect(new Function("return 42")()).toBe(42);
+        expect(new Function("foo", "return foo")(42)).toBe(42);
+        expect(new Function("foo,bar", "return foo + bar")(1, 2)).toBe(3);
+        expect(new Function("foo", "bar", "return foo + bar")(1, 2)).toBe(3);
+        expect(new Function("foo", "bar,baz", "return foo + bar + baz")(1, 2, 3)).toBe(6);
+        expect(new Function("foo", "bar", "baz", "return foo + bar + baz")(1, 2, 3)).toBe(6);
+        expect(new Function("foo", "if (foo) { return 42; } else { return 'bar'; }")(true)).toBe(
+            42
+        );
+        expect(new Function("foo", "if (foo) { return 42; } else { return 'bar'; }")(false)).toBe(
+            "bar"
+        );
+        expect(new Function("return typeof Function()")()).toBe("function");
+        expect(new Function("x", "return function (y) { return x + y };")(1)(2)).toBe(3);
+
+        expect(new Function("-->")()).toBeUndefined();
+
+        expect(new Function().name).toBe("anonymous");
+        expect(new Function().toString()).toBe("function anonymous() {\n  ???\n}");
+    });
+});
+
+describe("errors", () => {
+    test("syntax error", () => {
+        expect(() => {
+            new Function("[");
+        })
+            // This might be confusing at first but keep in mind it's actually parsing
+            // function anonymous() { [ }
+            // This is in line with what other engines are reporting.
+            .toThrowWithMessage(
+                SyntaxError,
+                "Unexpected token CurlyClose. Expected BracketClose (line: 4, column: 1)"
+            );
+    });
+});