Exclude pyc dirs, not include, when hashing code (#2286)

This fixes #2285 by fixing a minor typo in
f9a9d94 / #2263 that caused the
computation of a PEXes code hash to not recur into the correct
directories.

I think this explains the symptoms in #2285 due to caching: if a PEX
only contains files in subdirectories, the code hash will be
`da39a3ee5e6b4b0d3255bfef95601890afd80709` (the sha256 hash of no data)
and thus potentially the `venv create` might be referring to an
incorrectly cached installation.

pex/util.py

@@ -87,7 +87,7 @@ def pex_code_hash(cls, directory):
         hashing.dir_hash(
             directory=directory,
             digest=digest,
-            dir_filter=is_pyc_dir,
+            dir_filter=lambda d: not is_pyc_dir(d),
             file_filter=lambda file_path: not is_pyc_file(file_path)
             and not file_path.startswith("."),
         )

tests/test_util.py

@@ -6,12 +6,17 @@
 from hashlib import sha1
 from textwrap import dedent
 
+import pytest
+
 from pex.common import safe_mkdir, safe_open, temporary_dir, touch
 from pex.pex import PEX
 from pex.pex_builder import PEXBuilder
-from pex.typing import cast
+from pex.typing import TYPE_CHECKING, cast
 from pex.util import CacheHelper, DistributionHelper, named_temporary_file
 
+if TYPE_CHECKING:
+    from typing import Callable
+
 try:
     from unittest import mock
 except ImportError:
@@ -57,39 +62,49 @@ def test_hash():
         assert hash_output == empty_hash.hexdigest()
 
 
-def test_dir_hash():
-    # type: () -> None
+@pytest.mark.parametrize(
+    ("hasher", "includes_hidden_expected"),
+    [(CacheHelper.dir_hash, True), (CacheHelper.pex_code_hash, False)],
+)
+def test_directory_hasher(hasher, includes_hidden_expected):
+    # type: (Callable[[str], str], bool) -> None
     with temporary_dir() as tmp_dir:
         safe_mkdir(os.path.join(tmp_dir, "a", "b"))
         with safe_open(os.path.join(tmp_dir, "c", "d", "e.py"), "w") as fp:
             fp.write("contents1")
         with safe_open(os.path.join(tmp_dir, "f.py"), "w") as fp:
             fp.write("contents2")
-        hash1 = CacheHelper.dir_hash(tmp_dir)
+        hash1 = hasher(tmp_dir)
 
         os.rename(os.path.join(tmp_dir, "c"), os.path.join(tmp_dir, "c-renamed"))
-        assert hash1 != CacheHelper.dir_hash(tmp_dir)
+        assert hash1 != hasher(tmp_dir)
 
         os.rename(os.path.join(tmp_dir, "c-renamed"), os.path.join(tmp_dir, "c"))
-        assert hash1 == CacheHelper.dir_hash(tmp_dir)
+        assert hash1 == hasher(tmp_dir)
 
         touch(os.path.join(tmp_dir, "c", "d", "e.pyc"))
-        assert hash1 == CacheHelper.dir_hash(tmp_dir)
+        assert hash1 == hasher(tmp_dir)
         touch(os.path.join(tmp_dir, "c", "d", "e.pyc.123456789"))
-        assert hash1 == CacheHelper.dir_hash(tmp_dir)
+        assert hash1 == hasher(tmp_dir)
 
         pycache_dir = os.path.join(tmp_dir, "__pycache__")
         safe_mkdir(pycache_dir)
         touch(os.path.join(pycache_dir, "f.pyc"))
-        assert hash1 == CacheHelper.dir_hash(tmp_dir)
+        assert hash1 == hasher(tmp_dir)
         touch(os.path.join(pycache_dir, "f.pyc.123456789"))
-        assert hash1 == CacheHelper.dir_hash(tmp_dir)
+        assert hash1 == hasher(tmp_dir)
 
         touch(os.path.join(pycache_dir, "f.py"))
-        assert hash1 == CacheHelper.dir_hash(
+        assert hash1 == hasher(
             tmp_dir
         ), "All content under __pycache__ directories should be ignored."
 
+        with safe_open(os.path.join(tmp_dir, ".hidden"), "w") as fp:
+            fp.write("contents3")
+
+        includes_hidden = hash1 != hasher(tmp_dir)
+        assert includes_hidden == includes_hidden_expected
+
 
 try:
     import __builtin__ as python_builtins  # type: ignore[import]