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\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() { [ } // Since the body, surrounded by a newline on each side, is first parsed standalone, // we report unexpected token EOF instead of }. // FIXME: The position is odd though, I'd expect `line: 2, column: 2` and `line: 3, column: 1`... // > eval("\n[") // Uncaught exception: [SyntaxError] Unexpected token Eof. Expected BracketClose (line: 2, column: 2) // > eval("\n[\n") // Uncaught exception: [SyntaxError] Unexpected token Eof. Expected BracketClose (line: 2, column: 3) .toThrowWithMessage( SyntaxError, "Unexpected token Eof. Expected BracketClose (line: 2, column: 3)" ); }); test("parameters and body must be valid standalone", () => { expect(() => { new Function("/*", "*/ ) {"); }).toThrowWithMessage(SyntaxError, "Unterminated multi-line comment (line: 1, column: 3)"); }); });