test(bzlmod): Make some tests bzlmod compatible

A few tests weren't compatible with bzlmod, so would fail when it was
enabled. The various causes and fixes are:

* Under bzlmod, `runfiles.CurrentRepository()` returns the empty string
  for the main repository. To fix, an environment variable is used to
  tell the test whether bzlmod is enabled or not.

* Accessing data files through `TEST_SRCDIR` directly is error-prone
  under bzlmod because the directory name within runfiles changes from
  the workspace name to `_main`. To fix, use the runfiles libraries,
  which know how to map apparent repo names to the actual directory
  name. In the integration tests, the runfiles library isn't available,
  so just check for the `_main` directory instead.

Work towards bazelbuild#1469

examples/wheel/BUILD.bazel

@@ -323,4 +323,7 @@ py_test(
         ":python_requires_in_a_package",
         ":use_rule_with_dir_in_outs",
     ],
+    deps = [
+        "//python/runfiles",
+    ],
 )

examples/wheel/wheel_test.py

@@ -18,18 +18,23 @@
 import unittest
 import zipfile
 
+from python.runfiles import runfiles
+
 
 class WheelTest(unittest.TestCase):
     maxDiff = None
 
-    def test_py_library_wheel(self):
-        filename = os.path.join(
-            os.environ["TEST_SRCDIR"],
-            "rules_python",
-            "examples",
-            "wheel",
-            "example_minimal_library-0.0.1-py3-none-any.whl",
+    def setUp(self):
+        super().setUp()
+        self.runfiles = runfiles.Create()
+
+    def _get_path(self, filename):
+        return self.runfiles.Rlocation(
+            os.path.join("rules_python/examples/wheel", filename)
         )
+
+    def test_py_library_wheel(self):
+        filename = self._get_path("example_minimal_library-0.0.1-py3-none-any.whl")
         with zipfile.ZipFile(filename) as zf:
             self.assertEqual(
                 zf.namelist(),
@@ -43,11 +48,7 @@ def test_py_library_wheel(self):
             )
 
     def test_py_package_wheel(self):
-        filename = os.path.join(
-            os.environ["TEST_SRCDIR"],
-            "rules_python",
-            "examples",
-            "wheel",
+        filename = self._get_path(
             "example_minimal_package-0.0.1-py3-none-any.whl",
         )
         with zipfile.ZipFile(filename) as zf:
@@ -65,11 +66,7 @@ def test_py_package_wheel(self):
             )
 
     def test_customized_wheel(self):
-        filename = os.path.join(
-            os.environ["TEST_SRCDIR"],
-            "rules_python",
-            "examples",
-            "wheel",
+        filename = self._get_path(
             "example_customized-0.0.1-py3-none-any.whl",
         )
         with zipfile.ZipFile(filename) as zf:
@@ -154,31 +151,27 @@ def test_customized_wheel(self):
             )
 
     def test_legacy_filename_escaping(self):
-        filename = os.path.join(
-            os.environ['TEST_SRCDIR'],
-            'rules_python',
-            'examples',
-            'wheel',
-            'file_name_escaping-0.0.1_r7-py3-none-any.whl',
+        filename = self._get_path(
+            "file_name_escaping-0.0.1_r7-py3-none-any.whl",
         )
         with zipfile.ZipFile(filename) as zf:
             self.assertEquals(
                 zf.namelist(),
                 [
-                    'examples/wheel/lib/data.txt',
-                    'examples/wheel/lib/module_with_data.py',
-                    'examples/wheel/lib/simple_module.py',
-                    'examples/wheel/main.py',
+                    "examples/wheel/lib/data.txt",
+                    "examples/wheel/lib/module_with_data.py",
+                    "examples/wheel/lib/simple_module.py",
+                    "examples/wheel/main.py",
                     # PEP calls for replacing only in the archive filename.
                     # Alas setuptools also escapes in the dist-info directory
                     # name, so let's be compatible.
-                    'file_name_escaping-0.0.1_r7.dist-info/WHEEL',
-                    'file_name_escaping-0.0.1_r7.dist-info/METADATA',
-                    'file_name_escaping-0.0.1_r7.dist-info/RECORD',
+                    "file_name_escaping-0.0.1_r7.dist-info/WHEEL",
+                    "file_name_escaping-0.0.1_r7.dist-info/METADATA",
+                    "file_name_escaping-0.0.1_r7.dist-info/RECORD",
                 ],
             )
             metadata_contents = zf.read(
-                'file_name_escaping-0.0.1_r7.dist-info/METADATA'
+                "file_name_escaping-0.0.1_r7.dist-info/METADATA"
             )
             self.assertEquals(
                 metadata_contents,
@@ -192,11 +185,7 @@ def test_legacy_filename_escaping(self):
             )
 
     def test_filename_escaping(self):
-        filename = os.path.join(
-            os.environ["TEST_SRCDIR"],
-            "rules_python",
-            "examples",
-            "wheel",
+        filename = self._get_path(
             "file_name_escaping-0.0.1rc1+ubuntu.r7-py3-none-any.whl",
         )
         with zipfile.ZipFile(filename) as zf:
@@ -230,11 +219,7 @@ def test_filename_escaping(self):
             )
 
     def test_custom_package_root_wheel(self):
-        filename = os.path.join(
-            os.environ["TEST_SRCDIR"],
-            "rules_python",
-            "examples",
-            "wheel",
+        filename = self._get_path(
             "examples_custom_package_root-0.0.1-py3-none-any.whl",
         )
 
@@ -262,11 +247,7 @@ def test_custom_package_root_wheel(self):
                 self.assertFalse(line.startswith("/"))
 
     def test_custom_package_root_multi_prefix_wheel(self):
-        filename = os.path.join(
-            os.environ["TEST_SRCDIR"],
-            "rules_python",
-            "examples",
-            "wheel",
+        filename = self._get_path(
             "example_custom_package_root_multi_prefix-0.0.1-py3-none-any.whl",
         )
 
@@ -293,11 +274,7 @@ def test_custom_package_root_multi_prefix_wheel(self):
                 self.assertFalse(line.startswith("/"))
 
     def test_custom_package_root_multi_prefix_reverse_order_wheel(self):
-        filename = os.path.join(
-            os.environ["TEST_SRCDIR"],
-            "rules_python",
-            "examples",
-            "wheel",
+        filename = self._get_path(
             "example_custom_package_root_multi_prefix_reverse_order-0.0.1-py3-none-any.whl",
         )
 
@@ -324,11 +301,7 @@ def test_custom_package_root_multi_prefix_reverse_order_wheel(self):
                 self.assertFalse(line.startswith("/"))
 
     def test_python_requires_wheel(self):
-        filename = os.path.join(
-            os.environ["TEST_SRCDIR"],
-            "rules_python",
-            "examples",
-            "wheel",
+        filename = self._get_path(
             "example_python_requires_in_a_package-0.0.1-py3-none-any.whl",
         )
         with zipfile.ZipFile(filename) as zf:
@@ -359,11 +332,7 @@ def test_python_abi3_binary_wheel(self):
             "Windows": "win",
         }
         os_string = os_strings[platform.system()]
-        filename = os.path.join(
-            os.environ["TEST_SRCDIR"],
-            "rules_python",
-            "examples",
-            "wheel",
+        filename = self._get_path(
             f"example_python_abi3_binary_wheel-0.0.1-cp38-abi3-{os_string}_{arch}.whl",
         )
         with zipfile.ZipFile(filename) as zf:
@@ -396,11 +365,7 @@ def test_python_abi3_binary_wheel(self):
             )
 
     def test_rule_creates_directory_and_is_included_in_wheel(self):
-        filename = os.path.join(
-            os.environ["TEST_SRCDIR"],
-            "rules_python",
-            "examples",
-            "wheel",
+        filename = self._get_path(
             "use_rule_with_dir_in_outs-0.0.1-py3-none-any.whl",
         )
 
@@ -417,12 +382,8 @@ def test_rule_creates_directory_and_is_included_in_wheel(self):
             )
 
     def test_rule_expands_workspace_status_keys_in_wheel_metadata(self):
-        filename = os.path.join(
-            os.environ["TEST_SRCDIR"],
-            "rules_python",
-            "examples",
-            "wheel",
-            "example_minimal_library_BUILD_USER_-0.1._BUILD_TIMESTAMP_-py3-none-any.whl",
+        filename = self._get_path(
+            "example_minimal_library_BUILD_USER_-0.1._BUILD_TIMESTAMP_-py3-none-any.whl"
         )
 
         with zipfile.ZipFile(filename) as zf:

python/tests/toolchains/run_acceptance_test.py.tmpl

@@ -16,12 +16,17 @@ import os
 import subprocess
 import unittest
 
-
 class TestPythonVersion(unittest.TestCase):
     @classmethod
     def setUpClass(cls):
         os.chdir("%test_location%")
-        rules_python_path = os.path.join(os.environ["TEST_SRCDIR"], "rules_python")
+        test_srcdir = os.environ["TEST_SRCDIR"]
+        # When bzlmod is enabled, the name of the directory in runfiles changes
+        # to _main instead of rules_python
+        if os.path.exists(os.path.join(test_srcdir, "_main")):
+          rules_python_path = os.path.join(test_srcdir, "_main")
+        else:
+          rules_python_path = os.path.join(test_srcdir, "rules_python")
 
         test_tmpdir = os.environ["TEST_TMPDIR"]
         if %is_windows%:
@@ -57,13 +62,13 @@ class TestPythonVersion(unittest.TestCase):
 
     def test_match_toolchain(self):
         output = subprocess.check_output(
-          f"bazel run @python//:python3 -- --version",
+          f"bazel run --announce_rc @python//:python3 -- --version",
           shell = True, # Shell needed to look up via PATH
           text=True,
         ).strip()
         self.assertEqual(output, "Python %python_version%")
 
-        subprocess.run("bazel test //...", shell=True, check=True)
+        subprocess.run("bazel test --announce_rc //...", shell=True, check=True)
 
 
 if __name__ == "__main__":

tests/runfiles/BUILD.bazel

@@ -1,7 +1,11 @@
-load("@rules_python//python:defs.bzl", "py_test")
+load("@rules_python//python:py_test.bzl", "py_test")
+load("@rules_python//python/private:bzlmod_enabled.bzl", "BZLMOD_ENABLED")
 
 py_test(
     name = "runfiles_test",
     srcs = ["runfiles_test.py"],
+    env = {
+        "BZLMOD_ENABLED": "1" if BZLMOD_ENABLED else "0",
+    },
     deps = ["//python/runfiles"],
 )

tests/runfiles/runfiles_test.py

@@ -514,18 +514,14 @@ def testDirectoryBasedRlocationWithRepoMappingFromOtherRepo(self):
             )
 
     def testCurrentRepository(self):
-        # This test assumes that it is running without --enable_bzlmod as the
-        # correct result with Bzlmod would be the empty string - the canonical
-        # name # of the main repository. Without Bzlmod, the main repository is
-        # treated just like any other repository and has the name of its
-        # runfiles directory returned, which coincides with the name specified
-        # in the WORKSPACE file.
-        #
-        # Specify a fake runfiles directory to verify that its value isn't used
-        # by the function.
+        # Under bzlmod, the current repository name is the empty string instead
+        # of the name in the workspace file.
+        if bool(int(os.environ["BZLMOD_ENABLED"])):
+            expected = ""
+        else:
+            expected = "rules_python"
         self.assertEqual(
-            runfiles.Create({"RUNFILES_DIR": "whatever"}).CurrentRepository(),
-            "rules_python",
+            runfiles.Create({"RUNFILES_DIR": "whatever"}).CurrentRepository(), expected
         )
 
     @staticmethod