Improve test coverage for time.ts

[KyleJune]

I removed the last 2 tests here because they relied on system time and would intermittently fail. Need to figure out a better way to test FakeTime.

mock/time_test.ts

Lines 303 to 360 in a22be7f

	Deno.test("FakeTime ticks forward when advanceRate is set", async () => {
	let time: FakeTime = new FakeTime(null, { advanceRate: 1 });
	let start: number = Date.now();
	try {
	assertEquals(Date.now(), start);
	await delay(11);
	assertEquals(Date.now(), start + 10);
	await delay(6);
	assertEquals(Date.now(), start + 10);
	await delay(16);
	assertEquals(Date.now(), start + 30);
	time.restore();
	time = new FakeTime(null, { advanceRate: 1000 });
	start = Date.now();
	assertEquals(Date.now(), start);
	await delay(11);
	assertEquals(Date.now(), start + 10000);
	await delay(6);
	assertEquals(Date.now(), start + 10000);
	await delay(16);
	assertEquals(Date.now(), start + 30000);
	} finally {
	time.restore();
	}
	});
	Deno.test("FakeTime ticks forward at advanceFrequency when advanceRate is set", async () => {
	let time: FakeTime = new FakeTime(
	null,
	{ advanceRate: 1, advanceFrequency: 15 },
	);
	let start: number = Date.now();
	try {
	assertEquals(Date.now(), start);
	await delay(16);
	assertEquals(Date.now(), start + 15);
	await delay(11);
	assertEquals(Date.now(), start + 15);
	await delay(21);
	assertEquals(Date.now(), start + 45);
	time.restore();
	time = new FakeTime(null, { advanceRate: 1000, advanceFrequency: 15 });
	start = Date.now();
	assertEquals(Date.now(), start);
	await delay(16);
	assertEquals(Date.now(), start + 15000);
	await delay(11);
	assertEquals(Date.now(), start + 15000);
	await delay(21);
	assertEquals(Date.now(), start + 45000);
	} finally {
	time.restore();
	}
	});

[KyleJune]

I attempted to resolve the issue but the test would still intermittently fail on MacOS on GitHub actions. The failures were always related to it iterating forward faster than dictated by my delays. See the commits from that PR for more information about what I tried.

Open to suggestions on how to get test coverage for this behavior to be reliable in CI.