Revert "Add unittest"

This reverts commit a053a30.

Author: Theofilos Manitaras

unittests/resources/checks_unlisted/src/test.py

@@ -917,13 +917,3 @@ def test_fixture_resolution(run_reframe):
         action='run'
     )
     assert returncode == 0
-
-
-def test_check_stdin_not_a_tty(run_reframe, tmp_path):
-    returncode, stdout, stderr = run_reframe(
-        checkpath=[
-            'unittests/resources/checks_unlisted/test_stdin_not_a_tty.py'
-        ])
-    assert 'PASSED' in stdout
-    assert 'FAILED' not in stdout
-    assert returncode == 0