01a8e8b4e9
Keep the premade normal-function property layout when creating dynamic functions with a custom [[Prototype]], but transition the shape to that prototype instead of replacing it with %Function.prototype%. Let Function subclasses and bound functions created from their instances participate in instanceof checks, and keep bound super() construction passing the derived new.target through.
66 lines
3.1 KiB
JavaScript
66 lines
3.1 KiB
JavaScript
describe("correct behavior", () => {
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test("constructor properties", () => {
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expect(Function).toHaveLength(1);
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expect(Function.name).toBe("Function");
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expect(Function.prototype).toHaveLength(0);
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expect(Function.prototype.name).toBe("");
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});
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test("typeof", () => {
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expect(typeof Function()).toBe("function");
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expect(typeof new Function()).toBe("function");
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});
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test("basic functionality", () => {
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expect(Function()()).toBeUndefined();
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expect(new Function()()).toBeUndefined();
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expect(Function("return 42")()).toBe(42);
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expect(new Function("return 42")()).toBe(42);
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expect(new Function("foo", "return foo")(42)).toBe(42);
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expect(new Function("foo,bar", "return foo + bar")(1, 2)).toBe(3);
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expect(new Function("foo", "bar", "return foo + bar")(1, 2)).toBe(3);
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expect(new Function("foo", "bar,baz", "return foo + bar + baz")(1, 2, 3)).toBe(6);
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expect(new Function("foo", "bar", "baz", "return foo + bar + baz")(1, 2, 3)).toBe(6);
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expect(new Function("foo", "if (foo) { return 42; } else { return 'bar'; }")(true)).toBe(42);
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expect(new Function("foo", "if (foo) { return 42; } else { return 'bar'; }")(false)).toBe("bar");
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expect(new Function("return typeof Function()")()).toBe("function");
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expect(new Function("x", "return function (y) { return x + y };")(1)(2)).toBe(3);
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expect(new Function("-->")()).toBeUndefined();
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expect(new Function().name).toBe("anonymous");
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expect(new Function().toString()).toBe("function anonymous(\n) {\n\n}");
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});
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test("subclassed constructor returns a function with the subclass prototype", () => {
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class Subclass extends Function {}
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const sub = new Subclass("return 42");
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expect(sub()).toBe(42);
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expect(Object.getPrototypeOf(sub)).toBe(Subclass.prototype);
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expect(sub).toBeInstanceOf(Subclass);
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expect(sub).toBeInstanceOf(Function);
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});
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});
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describe("errors", () => {
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test("syntax error", () => {
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expect(() => {
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new Function("[");
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})
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// This might be confusing at first but keep in mind it's actually parsing
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// function anonymous() { [ }
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// Since the body, surrounded by a newline on each side, is first parsed standalone,
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// we report unexpected token EOF instead of }.
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// FIXME: The position is odd though, I'd expect `line: 2, column: 2` and `line: 3, column: 1`...
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// > eval("\n[") // Uncaught exception: [SyntaxError] Unexpected token Eof. Expected BracketClose (line: 2, column: 2)
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// > eval("\n[\n") // Uncaught exception: [SyntaxError] Unexpected token Eof. Expected BracketClose (line: 2, column: 3)
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.toThrowWithMessage(SyntaxError, "Unexpected token Eof. Expected BracketClose (line: 2, column: 3)");
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});
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test("parameters and body must be valid standalone", () => {
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expect(() => {
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new Function("/*", "*/ ) {");
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}).toThrowWithMessage(SyntaxError, "Unterminated multi-line comment (line: 1, column: 3)");
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});
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});
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