Open Radar

 
Summary:
Apparently Xcode 8.3 test suite is including a symbols from popular networking library CocoaAsyncSocket. Namely, GCDAsyncSocketDelegate. This may conflict with a custom version of the library used in the main app.

Steps to Reproduce:
1. Create a new project using Xcode and enable unit testing
2. Run the following test:
- (void)testExample {
    XCTAssertNil(NSProtocolFromString(@"GCDAsyncSocketDelegate"), @"This should be nil");
}

Expected Results:
NSProtocolFromString(@"GCDAsyncSocketDelegate") should return nil and the test should pass.

Actual Results:
The test fails because GCDAsyncSocketDelegate protocol exists at runtime. 

Regression:
This problem only started after upgrading to Xcode 8.3. My tests ran fine on previous version.

Notes:
I’ve determined which classes are implementing that protocol with the following code:

Class* classes = NULL;
    int numClasses = objc_getClassList(NULL, 0);
    if (numClasses > 0 ) {
        classes = (Class *)malloc(sizeof(Class) * numClasses);
        numClasses = objc_getClassList(classes, numClasses);
        for (int index = 0; index < numClasses; index++) {
            Class nextClass = classes[index];
            if (class_conformsToProtocol(nextClass, NSProtocolFromString(@"GCDAsyncSocketDelegate"))) {
                NSLog(@"%@", nextClass);
            }
        }
        free(classes);
    }

which prints:

 DTAssetHTTPRequestHandler
 DTAssetHTTPServer

Those two classes appear to be from Developer Tools provided with Xcode.