Update ClearCase tests to use build_client() and work without cleartool.
Review Request #12503 — Created Aug. 5, 2022 and submitted
This updates the ClearCase unit tests to build a
each test where it's needed, rather than in
setUp(). This is in
prepration for new tests that will need to handle client construction
Tests are no longer skipped if
cleartoolis missing. These tests mock
cleartoolinvocations, with the exception of the initial
cleartoolcheck and fetching host properties. With these set up with
spies, we no longer need to worry about whether
ClearCase unit tests pass.