Add a test for the --vsenv meson setup option

The tests and the unittests both unconditionally call setup_vsenv()
because all tests are run using the backend commands directly: ninja,
msbuild, etc.

There's no way to undo this vs env setup, so the only way to test that
--vsenv works is by:

1. Removing all paths in PATH that provide ninja
2. Changing setup_vsenv(force=True) to forcibly set-up a new vsenv
   when MESON_FORCE_VSENV_FOR_UNITTEST is set
3. Mock-patching build_command, test_command, install_command to use
   `meson` instead of `ninja`
4. Asserting that 'Activating VS' is in the output for all commands
5. Ensure that compilation works because ninja is picked up from the
   vs env.

I manually checked that this test actually does fail when the previous
commit is reverted.

1 files changed, 3 insertions, 3 deletions

diff --git a/unittests/baseplatformtests.py b/unittests/baseplatformtests.py
index 2f8064e..cfc78ce 100644
--- a/unittests/baseplatformtests.py
+++ b/unittests/baseplatformtests.py
@@ -249,10 +249,10 @@ class BasePlatformTests(TestCase):
 
     def run_tests(self, *, inprocess=False, override_envvars=None):
         if not inprocess:
-            self._run(self.test_command, workdir=self.builddir, override_envvars=override_envvars)
+            return self._run(self.test_command, workdir=self.builddir, override_envvars=override_envvars)
         else:
             with mock.patch.dict(os.environ, override_envvars):
-                run_mtest_inprocess(['-C', self.builddir])
+                return run_mtest_inprocess(['-C', self.builddir])[1]
 
     def install(self, *, use_destdir=True, override_envvars=None):
         if self.backend is not Backend.ninja:
@@ -263,7 +263,7 @@ class BasePlatformTests(TestCase):
                 override_envvars = destdir
             else:
                 override_envvars.update(destdir)
-        self._run(self.install_command, workdir=self.builddir, override_envvars=override_envvars)
+        return self._run(self.install_command, workdir=self.builddir, override_envvars=override_envvars)
 
     def uninstall(self, *, override_envvars=None):
         self._run(self.uninstall_command, workdir=self.builddir, override_envvars=override_envvars)