I searched on the internet, I have found that most the results show the term "the IELTS test" to talk about this kind of test in general, not a specific test.
Here are some examples:
(1)How to pass the IELTS test/exam?
Can I rewrite like this with the same meaning?
(1A)How to pass IELTS tests/exams?
(1B)How to pass an IELTS test/exam?
(2)The IELTS test is long. It takes 2 hours and 40 mins to do the test.
Can I rewrite like this with the same meaning?
(2A)An IELTS test is long. It takes 2 hours and 40 mins to do the test.
(3)The IELTS exam is the International English Language Testing System test taken to prove your IELTS proficiency.
Can I rewrite like this with the same meaning?
(3A)IELTS exams are the International English Language Testing System tests taken to prove your IELTS proficiency.