Light refactor; add test

Author: dougthor42

tests/tools/BUILD.bazel

@@ -0,0 +1,23 @@
+# Copyright 2025 The Bazel Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+load("//python:py_test.bzl", "py_test")
+
+licenses(["notice"])
+
+py_test(
+    name = "wheelmaker_test",
+    size = "small",
+    srcs = ["wheelmaker_test.py"],
+    deps = ["//tools:wheelmaker"],
+)

tests/tools/wheelmaker_test.py

@@ -0,0 +1,27 @@
+import unittest
+
+import tools.wheelmaker as wheelmaker
+
+
+class ArcNameFromTest(unittest.TestCase):
+
+    def test_arcname_from(self) -> None:
+
+        # (name, distribution_prefix, strip_path_prefixes, want) tuples
+        checks = [
+            ("foo/bar/baz/file.py", "", [], "foo/bar/baz/file.py"),
+            ("foo/bar/baz/file.py", "", ["foo"], "/bar/baz/file.py"),
+            ("foo/bar/baz/file.py", "", ["foo/"], "bar/baz/file.py"),
+            ("foo/bar/baz/file.py", "", ["foo/bar"], "/baz/file.py"),
+            ("foo/bar/baz/file.py", "", ["foo/bar", "baz"], "/baz/file.py"),
+            ("foo/bar/baz/file.py", "", ["foo", "bar"], "/bar/baz/file.py"),
+            ("foo/bar/baz/file.py", "", ["baz", "foo/bar"], "/baz/file.py"),
+        ]
+        for name, prefix, strip, want in checks:
+            with self.subTest(name=name, distribution_prefix=prefix, strip_path_prefixes=strip, want=want):
+                got = wheelmaker.arcname_from(name=name, distribution_prefix=prefix, strip_path_prefixes=strip)
+                self.assertEqual(got, want)
+
+
+if __name__ == "__main__":
+    unittest.main()

tools/wheelmaker.py

@@ -98,6 +98,19 @@ def normalize_pep440(version):
         return str(packaging.version.Version(f"0+{sanitized}"))
 
 
+def arcname_from(name: str, distribution_prefix: str, strip_path_prefixes:list[str] | None = None):
+    # Always use unix path separators.
+    normalized_arcname = name.replace(os.path.sep, "/")
+    # Don't manipulate names filenames in the .distinfo or .data directories.
+    if distribution_prefix and normalized_arcname.startswith(distribution_prefix):
+        return normalized_arcname
+    for prefix in strip_path_prefixes:
+        if normalized_arcname.startswith(prefix):
+            return normalized_arcname[len(prefix) :]
+
+    return normalized_arcname
+
+
 class _WhlFile(zipfile.ZipFile):
     def __init__(
         self,
@@ -126,18 +139,6 @@ def data_path(self, basename):
     def add_file(self, package_filename, real_filename):
         """Add given file to the distribution."""
 
-        def arcname_from(name):
-            # Always use unix path separators.
-            normalized_arcname = name.replace(os.path.sep, "/")
-            # Don't manipulate names filenames in the .distinfo or .data directories.
-            if normalized_arcname.startswith(self._distribution_prefix):
-                return normalized_arcname
-            for prefix in self._strip_path_prefixes:
-                if normalized_arcname.startswith(prefix):
-                    return normalized_arcname[len(prefix) :]
-
-            return normalized_arcname
-
         if os.path.isdir(real_filename):
             directory_contents = os.listdir(real_filename)
             for file_ in directory_contents: