Should I use "a test" or "the test"?

Question

The test I am talking about is the IELTS test. On the one hand, I feel that I should use the test to refer to the IELTS test. On the other hand, there are IELTS tests you can choose to take on different days. This makes feel that I should use a test to refer to one of the IELTS tests he booked. Should I use a test or the test? I don't want to mention "IELTS" in the question because we both know we are talking about the IELTS test.

Have you book the/a test?

Answer 1

In the specific situation probably "Have you booked your test?"

Otherwise, a specific instance of the test is "the test", one, undetermined test is "a test"

You will learn all the basic grammar of English and then take an IELTS test at the end of the course. The IELTS test will help you when you apply to a university in the UK.

First mention, the test is not determined, so "a test", second mention it is determined by the previous mention, so "the test".