Global values

As it often does, the test begins from the setup. In this case, the setup includes the introduction of both beforeAll and afterAll hooks to the test suite.

beforeAll(() => {
  vi.stubGlobal('location', new URL('http://localhost/base/'))
})

In the beforeAll() hook, I'm using the vi.stubGlobal() function to replace the value of the global property location with a mocked URL instance. I intentionally provide a mock URL with a path (/base/) to make sure that the toAbsoluteUrl() function handles relative paths correctly.

And, of course, I am making sure that the global location object is unstubbed by calling vi.unstubAllGlobals() in the afterAll() hook.

afterAll(() => {
  vi.unstubAllGlobals()
})

Now, to the test cases!

The first one is about the scenario where an absolute URL provided to the tested function is returned as-is. That's precisely what I will do:

test('returns an absolute url as-is', () => {
  expect(toAbsoluteUrl('https://example.com/')).toBe('https://example.com/')
})

The next scenario involves handling relative URLs that only include paths. In itself, it can be split into two use cases:

When an absolute path is provided (e.g. /abc);
When a relative path is provided (e.g. ./abc; notice the dot .).

While both being based on the mocked location.href, these two scenarios will yield different URLs, which I make sure to cover in tests:

test('resolves a relative url against the current location', () => {
  expect(toAbsoluteUrl('/resource')).toBe('http://localhost/resource')
  expect(toAbsoluteUrl('./resource')).toBe('http://localhost/base/resource')
})

By mocking the value of location in this test suite, I have isolated it. Everything that affects the test results of the toAbsoluteUrl() function is now contained within this single test file.

04. Globals/02. Global values (🏁 solution)

Global values