Validate Bazel uses correct Python version

Signed-off-by: Cade Daniel <cade@anyscale.com>

ci/ci.sh

@@ -743,10 +743,13 @@ build() {
 }
 
 run_minimal_test() {
+  EXPECTED_PYTHON_VERSION=$1
   BAZEL_EXPORT_OPTIONS="$(./ci/run/bazel_export_options)"
   # Ignoring shellcheck is necessary because if ${BAZEL_EXPORT_OPTIONS} is wrapped by the double quotation,
   # bazel test cannot recognize the option.
   # shellcheck disable=SC2086
+  bazel test --test_output=streamed --config=ci --test_env=RAY_MINIMAL=1 --test_env=EXPECTED_PYTHON_VERSION=$EXPECTED_PYTHON_VERSION ${BAZEL_EXPORT_OPTIONS} python/ray/tests/test_minimal_install
+  # shellcheck disable=SC2086
   bazel test --test_output=streamed --config=ci --test_env=RAY_MINIMAL=1 ${BAZEL_EXPORT_OPTIONS} python/ray/tests/test_basic
   # shellcheck disable=SC2086
   bazel test --test_output=streamed --config=ci --test_env=RAY_MINIMAL=1 --test_env=TEST_EXTERNAL_REDIS=1 ${BAZEL_EXPORT_OPTIONS} python/ray/tests/test_basic

python/ray/tests/BUILD

@@ -199,6 +199,7 @@ py_test_module_list(
     "test_metrics_agent_2.py",
     "test_microbenchmarks.py",
     "test_mini.py",
+    "test_minimal_install.py",
     "test_numba.py",
     "test_redis_tls.py",
     "test_raylet_output.py",

python/ray/tests/test_minimal_install.py

@@ -0,0 +1,26 @@
+# coding: utf-8
+"""
+Tests that are specific to minimal installations.
+"""
+
+import pytest
+import os
+import sys
+
+@pytest.mark.skipif(os.environ.get("RAY_MINIMAL", "0") != "1", reason="Skip unless running in a minimal install.")
+def test_correct_python_version():
+    """
+    Validate that Bazel uses the correct Python version in our minimal tests.
+    """
+    expected_python_version = os.environ.get("EXPECTED_PYTHON_VERSION", '').strip()
+    assert expected_python_version, f"EXPECTED_PYTHON_VERSION is {expected_python_version=}"
+
+    actual_major, actual_minor = sys.version_info[:2]
+    actual_version = f"{actual_major}.{actual_minor}"
+    assert actual_version == expected_python_version, f"{expected_python_version=} {actual_version=}"
+
+if __name__ == "__main__":
+    if os.environ.get("PARALLEL_CI"):
+        sys.exit(pytest.main(["-n", "auto", "--boxed", "-vs", __file__]))
+    else:
+        sys.exit(pytest.main(["-sv", __file__]))