simplify the code a bit

Author: philsc

tests/interpreter/BUILD.bazel

@@ -14,6 +14,9 @@
 
 load(":interpreter_tests.bzl", "PYTHON_VERSIONS_TO_TEST", "py_reconfig_interpreter_tests")
 
+# For this test the interpreter is sourced from the current configuration. That
+# means both the interpreter and the test itself are expected to run under the
+# same Python version.
 py_reconfig_interpreter_tests(
     name = "interpreter_version_test",
     srcs = ["interpreter_test.py"],
@@ -23,26 +26,26 @@ py_reconfig_interpreter_tests(
     env = {
         "PYTHON_BIN": "$(rootpath //python/bin:python)",
     },
-    # Both the interpreter and the test itself are expected to run under
-    # the same version.
-    expected_interpreter_version = None,
     main = "interpreter_test.py",
     python_versions = PYTHON_VERSIONS_TO_TEST,
 )
 
+# For this test the interpreter is sourced from a binary pinned at a specific
+# Python version. That means the interpreter and the test itself can run
+# different Python versions.
 py_reconfig_interpreter_tests(
     name = "python_src_test",
     srcs = ["interpreter_test.py"],
     data = [
         "//python/bin:python",
     ],
     env = {
+        # Since we're grabbing the interpreter from a binary with a fixed
+        # version, we expect to always see that version. It doesn't matter what
+        # Python version the test itself is running with.
+        "EXPECTED_INTERPRETER_VERSION": "3.11",
         "PYTHON_BIN": "$(rootpath //python/bin:python)",
     },
-    # Since we're grabbing the interpreter from a binary with a fixed
-    # version, we expect to always see that version. It doesn't matter what
-    # Python version the test itself is running with.
-    expected_interpreter_version = "3.11",
     main = "interpreter_test.py",
     python_src = "//tools/publish:twine",
     python_versions = PYTHON_VERSIONS_TO_TEST,

tests/interpreter/interpreter_test.py

@@ -23,15 +23,17 @@ def setUp(self):
         super().setUp()
         self.interpreter = os.environ["PYTHON_BIN"]
 
+        v = sys.version_info
+        self.version = f"{v.major}.{v.minor}"
+
     def test_self_version(self):
         """Performs a sanity check on the Python version used for this test."""
         expected_version = os.environ["EXPECTED_SELF_VERSION"]
-        v = sys.version_info
-        self.assertEqual(expected_version, f"{v.major}.{v.minor}")
+        self.assertEqual(expected_version, self.version)
 
     def test_interpreter_version(self):
         """Validates that we can successfully execute arbitrary code from the CLI."""
-        expected_version = os.environ["EXPECTED_INTERPRETER_VERSION"]
+        expected_version = os.environ.get("EXPECTED_INTERPRETER_VERSION", self.version)
 
         try:
             result = subprocess.check_output(

tests/interpreter/interpreter_tests.bzl

@@ -16,18 +16,32 @@
 
 load("//tests/support:sh_py_run_test.bzl", "py_reconfig_test")
 
+# The versions of Python that we want to run the interpreter tests against.
 PYTHON_VERSIONS_TO_TEST = (
     "3.10",
     "3.11",
     "3.12",
 )
 
-def py_reconfig_interpreter_tests(name, python_versions, expected_interpreter_version = None, env = {}, **kwargs):
+def py_reconfig_interpreter_tests(name, python_versions, env = {}, **kwargs):
+    """Runs the specified test against each of the specified Python versions.
+
+    One test gets generated for each Python version. The following environment
+    variable gets set for the test:
+
+        EXPECTED_SELF_VERSION: Contains the Python version that the test itself
+            is running under.
+
+    Args:
+        name: Name of the test.
+        python_versions: A list of Python versions to test.
+        env: The environment to set on the test.
+        **kwargs: Passed to the underlying py_reconfig_test targets.
+    """
     for python_version in python_versions:
         py_reconfig_test(
             name = "{}_{}".format(name, python_version),
             env = env | {
-                "EXPECTED_INTERPRETER_VERSION": expected_interpreter_version or python_version,
                 "EXPECTED_SELF_VERSION": python_version,
             },
             python_version = python_version,