Answer: You can detect memory leaks automatically in unit tests by attaching an addTeardownBlock to XCTestCase with a weak reference to the system under test and asserting that the instance deallocates to nil.

Because XCTestCase.addTeardownBlock executes after each test method completes and local scopes have exited, any properly managed instance will have a retain count of zero and become nil. If a retain cycle exists (e.g. inside a ViewModel, Coordinator, or View Controller), the weak pointer remains non-nil, triggering an immediate test failure.

Reusable Test Helper:

import XCTest

extension XCTestCase {
    /// Tracks an object instance and asserts that it deallocates after the test finishes.
    func trackForMemoryLeaks(
        _ instance: AnyObject,
        file: StaticString = #filePath,
        line: UInt = #line
    ) {
        addTeardownBlock { [weak instance] in
            XCTAssertNil(
                instance,
                "Instance should have been deallocated. Potential memory leak detected.",
                file: file,
                line: line
            )
        }
    }
}

Unit Test Example:

final class ProfileViewModelTests: XCTestCase {
    
    func test_viewModel_doesNotLeakOnEventCallback() {
        var sut: ProfileViewModel? = ProfileViewModel()
        
        // Track sut for leaks before exercising behaviour
        trackForMemoryLeaks(sut!)
        
        // Trigger bindings and callbacks
        sut?.setupBindings()
        sut?.simulateUserAction()
        
        // Nil out reference to simulate end of screen lifecycle
        sut = nil
        // addTeardownBlock will run and assert weak reference is nil!
    }
}

Integration into CI/CD Pipelines:

• Prevents memory leak regressions before code merges into main
• Runs in milliseconds as standard unit tests without requiring Instruments or UI automation
• Can be applied to ViewControllers, ViewModels, Presenters, Coordinators, and Services