How to do "assert no difference" and "assert difference" in Swift

CustomAsserts.swift

func XCTAssertNoDifference<T>(_ context: NSManagedObjectContext, request: NSFetchRequest<T>, file: StaticString = #file, line: UInt = #line, work: () -> Void) {
    let oldCount = try! context.count(for: request)
    
    work()
    
    let newCount = try! context.count(for: request)
    XCTAssertEqual(oldCount, newCount, "Count incorrectly changed: \(oldCount) to \(newCount)", file: file, line: line)
}

func XCTAssertDifference<T>(_ context: NSManagedObjectContext, request: NSFetchRequest<T>, difference: Int, file: StaticString = #file, line: UInt = #line, work: () -> Void) {
    let oldCount = try! context.count(for: request)
    
    work()
    
    let newCount = try! context.count(for: request)
    XCTAssertEqual(oldCount + difference, newCount, "Count incorrectly changed: \(oldCount) + \(difference) to \(newCount)", file: file, line: line)
}