XCTest: Wait for async call to finish in synchronous function

Question

I have a synchronous function that calls an asynchronous sub function. Now I want to test that the synchronous function sets a property. I've seen many examples of tests using expectations, but since only the sub function is async, I can't set fulfill.

What I would like to do instead is to just do an XCTAssertEqual checking the property to equal a certain value within a given timeout period.

How can this be done?

Here's a sketch:

class TestSubject {
    var noOfCalls = 0

    func funcToTest() {
        Task.init {
            await doSomething()
            await doSomething()
        }
    }

    func doSomething() async {
        ...
        noOfCalls++
    }
}

The test:

func testTestSubject() async {
    var subject = TestSubject()

    subject.funcToTest()

    // this obviously doesn't work because of the async call
    XCTAssertEqual(subject.noOfCalls, 2)
}