Use cmake-derived Python executable.

Author: josephbirkner

README.md

@@ -107,6 +107,8 @@ add_wheel_test(mylib-test
 )
 ```
 
+By default, `add_wheel_test(...)` creates the temporary virtual environment using the same `Python3_EXECUTABLE` that CMake found. To override the interpreter used for the venv, set `PYTHON_WHEEL_TEST_EXECUTABLE` in the environment at configure time, or override the test's `ENVIRONMENT` property.
+
 ## Building Docker Images
 
 To build the manylinux Docker images for different architectures:

python-wheel.cmake

@@ -220,6 +220,12 @@ function (add_wheel_test TEST_NAME)
     "WORKING_DIRECTORY"
     "COMMANDS" ${ARGN})
 
+  set(wheel_test_python_executable "${Python3_EXECUTABLE}")
+  if (DEFINED ENV{PYTHON_WHEEL_TEST_EXECUTABLE} AND NOT "$ENV{PYTHON_WHEEL_TEST_EXECUTABLE}" STREQUAL "")
+    set(wheel_test_python_executable "$ENV{PYTHON_WHEEL_TEST_EXECUTABLE}")
+  endif()
+  file(TO_CMAKE_PATH "${wheel_test_python_executable}" wheel_test_python_executable_cmake_path)
+
   add_test(
     NAME
       ${TEST_NAME}
@@ -229,4 +235,7 @@ function (add_wheel_test TEST_NAME)
       bash "${TEST_WHEEL_BASH}"
         -w "${WHEEL_DEPLOY_DIRECTORY}"
         ${WHEEL_TEST_COMMANDS})
+
+  set_property(TEST ${TEST_NAME} APPEND PROPERTY
+    ENVIRONMENT "PYTHON_WHEEL_TEST_EXECUTABLE=${wheel_test_python_executable_cmake_path}")
 endfunction()

test-wheel.bash

@@ -2,13 +2,25 @@
 
 set -e
 
-my_dir="$( cd "$( dirname "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"
-. "$my_dir/python.bash"
+venv_python="${PYTHON_WHEEL_TEST_EXECUTABLE:-}"
+if [[ -z "$venv_python" ]]; then
+  echo "PYTHON_WHEEL_TEST_EXECUTABLE is not set; using 'python3' from PATH." >&2
+  venv_python="python3"
+fi
 
 venv=$(mktemp -d)
-echo "→ Setting up a virtual environment in $venv using python '$(which python3)' ($(python3 --version))..."
-python3 -m venv "$venv"
+echo "→ Setting up a virtual environment in $venv using python '$venv_python' ($("$venv_python" --version))..."
+
+"$venv_python" -m venv "$venv"
+
+activate_path="bin/activate"
+if [[ -f "$venv/Scripts/activate" ]]; then
+  activate_path="Scripts/activate"
+fi
+
+# shellcheck disable=SC1090
 source "$venv/$activate_path"
+
 python -m pip install -U pip
 pip install pytest
 
@@ -18,7 +30,7 @@ trap '
   failed_pids=()
   for pid in $(jobs -p); do
     if kill -0 $pid >/dev/null 2>&1; then
-      # Background process is still running - good.
+      # Background process is still running - kill it.
       kill $pid
     else
       exit_status=$?