How to unit test asynchronous APIs?

Question

I have installed Google Toolbox for Mac into Xcode and followed the instructions to set up unit testing found here.

It all works great, and I can test my synchronous

Answer 1

I find it very convenient to use https://github.com/premosystems/XCAsyncTestCase

It adds three very handy methods to XCTestCase

@interface XCTestCase (AsyncTesting)

- (void)waitForStatus:(XCTAsyncTestCaseStatus)status timeout:(NSTimeInterval)timeout;
- (void)waitForTimeout:(NSTimeInterval)timeout;
- (void)notify:(XCTAsyncTestCaseStatus)status;

@end

that allow very clean tests. An example from the project itself:

- (void)testAsyncWithDelegate
{
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.google.com"]];
    [NSURLConnection connectionWithRequest:request delegate:self];
    [self waitForStatus:XCTAsyncTestCaseStatusSucceeded timeout:10.0];
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSLog(@"Request Finished!");
    [self notify:XCTAsyncTestCaseStatusSucceeded];
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    NSLog(@"Request failed with error: %@", error);
    [self notify:XCTAsyncTestCaseStatusFailed];
}