Simple:

I write a test every week to assess my students' knowledge.She writes a test in the morning before her classes begin.The teacher writes a test for the students to complete by the end of the week.They write a test together to practice their skills.

Perfect:

I have written a test for my students to take next week.She has written a test that covers all the material we have studied.The teacher has written a test that will challenge the students' understanding.They have written a test to help each other prepare for the exam.

Perfect Continuous:

I have been writing a test for hours and I'm finally finished.She has been writing a test since yesterday and it's almost ready.The teacher has been writing a test that will require critical thinking skills.They have been writing a test together to ensure it is comprehensive.

Забыл $Forgot$:

I forgot to write a test for my students last week.She forgot to write a test for the class, so they had a free period.The teacher forgot to write a test, so the students were relieved.They forgot to write a test for each other, so they had to do extra practice.