Fixed unbound cmvers variable

[mensinda]

Fixes a crash.

[jon-turney]

Can you explain why this case wasn't hit by the test added in #4444? Is it possible to add something to exercise this case (per http://mesonbuild.com/Contributing.html#tests)

[mensinda]

This bug is triggered when CMake is not found by meson. Since CMake is installed in all test environments this bug doesn't occur there. I will try to add a unit test for this, which should be possible since the CMake executable can also be retrieved via os.environ['CMAKE']. Though I don't know if it is OK to set environment variables in unit tests.

[lazka]

master hit this now because the azure msys2 build doesn't have cmake installed (should it? I didn't see a test difference)

[mensinda]

The test currently should only run on Linux (it is in the linuxlike directory). It seams like this bug was triggerd in another test case where the first dependcy method failed. In this case CMake is automatically used as a fallback. I have not looked at the specific test case yet.

In short yes.

[mensinda]

The CI still fails. I am looking into it.

[mensinda]

The caused by the CMake backend raising an exception with the message "CMake not found" but the test_dependency unit test requires an exception with the format [Dd]ependency.*not found. The CMake backend raises multiple other exceptions with different messages. Should I update the unit test or the messages in the exception?

[mensinda]

@lazka Actually no. Azure does not need CMake since the tests (currently) only run on Linux. Though this might change in the future.

[lazka]

thanks @mensinda. There is still an error on master

======================================================================
FAIL: test_dependency (__main__.FailureTests)
----------------------------------------------------------------------
mesonbuild.dependencies.base.DependencyException: CMake not found.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "run_unittests.py", line 117, in wrapped
    return f(*args, **kwargs)
  File "run_unittests.py", line 2999, in test_dependency
    self.assertMesonRaises(contents, match)
  File "run_unittests.py", line 2956, in assertMesonRaises
    self.init(self.srcdir, extra_args=extra_args, inprocess=True)
AssertionError: "[Dd]ependency.*not found" does not match "CMake not found." : dependency('zlibfail')

I've opened #4552 to install cmake for msys2 which makes things work here.