Testing your knowledge of conversational Spanish is easy. In a classroom setting, the tutor will set tests to assess your progress in speaking Spanish. Many of the free online Spanish courses have quizzes to test grammar, vocabulary and conversation. Consider renting a Spanish film to see how much of the conversation you understand. This will provide a good self-test. The ultimate test is to speak Spanish with native speakers. If you can understand what they say and be understood, then you can be sure that your ability to speak conversational Spanish is progressing nicely.