jcs.org
Serenity Operating System
1describe("correct behavior", () => {
2 test("basic functionality", () => {
3 let n = 0;
4 expect(++n).toBe(1);
5 expect(n).toBe(1);
6
7 n = 0;
8 expect(n++).toBe(0);
9 expect(n).toBe(1);
10
11 n = 0;
12 expect(--n).toBe(-1);
13 expect(n).toBe(-1);
14
15 n = 0;
16 expect(n--).toBe(0);
17 expect(n).toBe(-1);
18
19 let a = [];
20 expect(a++).toBe(0);
21 expect(a).toBe(1);
22
23 let b = true;
24 expect(b--).toBe(1);
25 expect(b).toBe(0);
26 });
27
28 test("updates that produce NaN", () => {
29 let s = "foo";
30 expect(++s).toBeNaN();
31 expect(s).toBeNaN();
32
33 s = "foo";
34 expect(s++).toBeNaN();
35 expect(s).toBeNaN();
36
37 s = "foo";
38 expect(--s).toBeNaN();
39 expect(s).toBeNaN();
40
41 s = "foo";
42 expect(s--).toBeNaN();
43 expect(s).toBeNaN();
44 });
45});
46
47describe("errors", () => {
48 test("update expression throws reference error", () => {
49 expect(() => {
50 ++x;
51 }).toThrowWithMessage(ReferenceError, "'x' is not defined");
52 });
53});