When unit testing asynchronous code like a completion handler, we could end up with false positives in case we just add some assert in the completion block. A better strategy is shown in the following sample. We will eliminate the false positive by the use of the waitForExpectations function.
class AsyncUnitTests: XCTestCase {
func testGivenValidConnectionShouldReturnThatFeatureFlagIsDisabled() {
let asyncMock = MockAsyncStuff()
let fetchFeatureFlagsExpectation = expectation(description: "fetchFeatureFlags")
asyncMock.fetchFlagsWithCompletionHandler { (isDisabled) in
fetchFeatureFlagsExpectation.fulfill()
XCTAssertTrue(isDisabled)
}
waitForExpectations(timeout: 5, handler: nil)
}
}