run_tests: fix pytest selection inside tox venv

Finding the "right" pytest is challenging.  In Debian, `pytest` is
Python 2 while `pytest-3` is the Python 3 version ... but only when
outside of a virtualenv.  Inside of a virtualenv (e.g. the ones that
tox creates), we always want `pytest`.

Change-Id: Ic1fe84c10f06227bceeb9baad6a3c4598bbe9860
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/303802
Reviewed-by: Peter Kjellerstedt <peter.kjellerstedt@gmail.com>
Reviewed-by: Mike Frysinger <vapier@google.com>
Tested-by: Mike Frysinger <vapier@google.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/run_tests b/run_tests
index 6c6f8594..573dd446 100755
--- a/run_tests
+++ b/run_tests
@@ -24,6 +24,10 @@ import sys
 
 def find_pytest():
   """Try to locate a good version of pytest."""
+  # If we're in a virtualenv, assume that it's provided the right pytest.
+  if 'VIRTUAL_ENV' in os.environ:
+    return 'pytest'
+
   # Use the Python 3 version if available.
   ret = shutil.which('pytest-3')
   if ret: