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LibJS: Add Array.prototype.keys()

This commit is contained in:
davidot 2021-06-12 14:43:58 +02:00 committed by Linus Groh
parent dc65f54c06
commit e044a3e428
3 changed files with 56 additions and 0 deletions

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@ -0,0 +1,44 @@
test("length", () => {
expect(Array.prototype.keys.length).toBe(0);
});
test("basic functionality", () => {
const a = ["a", "b", "c"];
const it = a.keys();
expect(it.next()).toEqual({ value: 0, done: false });
expect(it.next()).toEqual({ value: 1, done: false });
expect(it.next()).toEqual({ value: 2, done: false });
expect(it.next()).toEqual({ value: undefined, done: true });
expect(it.next()).toEqual({ value: undefined, done: true });
expect(it.next()).toEqual({ value: undefined, done: true });
});
test("works when applied to non-object", () => {
[true, false, 9, 2n, Symbol()].forEach(primitive => {
const it = [].keys.call(primitive);
expect(it.next()).toEqual({ value: undefined, done: true });
expect(it.next()).toEqual({ value: undefined, done: true });
expect(it.next()).toEqual({ value: undefined, done: true });
});
});
test("item added to array before exhaustion is accessible", () => {
const a = ["a", "b"];
const it = a.keys();
expect(it.next()).toEqual({ value: 0, done: false });
expect(it.next()).toEqual({ value: 1, done: false });
a.push("c");
expect(it.next()).toEqual({ value: 2, done: false });
expect(it.next()).toEqual({ value: undefined, done: true });
expect(it.next()).toEqual({ value: undefined, done: true });
});
test("item added to array after exhaustion is inaccessible", () => {
const a = ["a", "b"];
const it = a.keys();
expect(it.next()).toEqual({ value: 0, done: false });
expect(it.next()).toEqual({ value: 1, done: false });
expect(it.next()).toEqual({ value: undefined, done: true });
a.push("c");
expect(it.next()).toEqual({ value: undefined, done: true });
});