public async Task SearchContainCommandHandler_ContainsRequest_true(string request)
        {
            var command = new SearchContainCommand(request);
            var token   = new CancellationToken();
            var handler =
                new SearchContainCommandHandler().Handle(null, token);

            await Assert.ThrowsAnyAsync <ArgumentNullException>(() =>
                                                                handler);
        }
        public async Task ThrowArgumentNullException_RequestsRequestIsInvalid(string request)
        {
            var command = new SearchContainCommand(request);
            var token   = new CancellationToken();
            var handler =
                new SearchContainCommandHandler().Handle(command, token);

            await Assert.ThrowsAnyAsync <ArgumentNullException>(() =>
                                                                handler);
        }