LibJS: Improve Error/NativeError tests

Some of this stuff is already tested properly in the name and message
prototype tests, so let's focus on covering all error types here as well
instead.

Userland/Libraries/LibJS/Tests/builtins/Error/Error.js

@@ -1,18 +1,34 @@
-test("basic functionality", () => {
-    expect(Error).toHaveLength(1);
-    expect(Error.name).toBe("Error");
-});
+describe("normal behavior", () => {
+    test("length is 1", () => {
+        expect(Error).toHaveLength(1);
+        expect(EvalError).toHaveLength(1);
+        expect(RangeError).toHaveLength(1);
+        expect(ReferenceError).toHaveLength(1);
+        expect(SyntaxError).toHaveLength(1);
+        expect(TypeError).toHaveLength(1);
+    });
 
-test("name", () => {
-    [Error(), Error(undefined), Error("test"), Error(42), Error(null)].forEach(error => {
-        expect(error.name).toBe("Error");
+    test("name matches constructor name", () => {
+        expect(Error.name).toBe("Error");
+        expect(EvalError.name).toBe("EvalError");
+        expect(RangeError.name).toBe("RangeError");
+        expect(ReferenceError.name).toBe("ReferenceError");
+        expect(SyntaxError.name).toBe("SyntaxError");
+        expect(TypeError.name).toBe("TypeError");
     });
-});
 
-test("message", () => {
-    expect(Error().message).toBe("");
-    expect(Error(undefined).message).toBe("");
-    expect(Error("test").message).toBe("test");
-    expect(Error(42).message).toBe("42");
-    expect(Error(null).message).toBe("null");
+    test("basic functionality", () => {
+        expect(Error()).toBeInstanceOf(Error);
+        expect(new Error()).toBeInstanceOf(Error);
+        expect(EvalError()).toBeInstanceOf(EvalError);
+        expect(new EvalError()).toBeInstanceOf(EvalError);
+        expect(RangeError()).toBeInstanceOf(RangeError);
+        expect(new RangeError()).toBeInstanceOf(RangeError);
+        expect(ReferenceError()).toBeInstanceOf(ReferenceError);
+        expect(new ReferenceError()).toBeInstanceOf(ReferenceError);
+        expect(SyntaxError()).toBeInstanceOf(SyntaxError);
+        expect(new SyntaxError()).toBeInstanceOf(SyntaxError);
+        expect(TypeError()).toBeInstanceOf(TypeError);
+        expect(new TypeError()).toBeInstanceOf(TypeError);
+    });
 });