Merge pull request #248 from LarrysGIT/main

Extend Windows system executable extensions

distutils/spawn.py

@@ -7,6 +7,8 @@
 """
 
 import os
+import pathlib
+import platform
 import subprocess
 import sys
 
@@ -68,19 +70,19 @@ def spawn(cmd, search_path=1, verbose=0, dry_run=0, env=None):  # noqa: C901
         raise DistutilsExecError(f"command {cmd!r} failed with exit code {exitcode}")
 
 
-def find_executable(executable, path=None):
-    """Tries to find 'executable' in the directories listed in 'path'.
-
-    A string listing directories separated by 'os.pathsep'; defaults to
-    os.environ['PATH'].  Returns the complete filename or None if not found.
+def _executable_candidates(executable: pathlib.Path):
+    """
+    Given an executable, yields common executable variants.
     """
-    _, ext = os.path.splitext(executable)
-    if (sys.platform == 'win32') and (ext != '.exe'):
-        executable = executable + '.exe'
+    yield executable
+    if platform.system() != 'Windows':
+        return
+    exts = os.environ.get('PATHEXT').split(os.pathsep)
+    unique = (ext for ext in exts if executable.suffix.casefold() != ext.casefold())
+    yield from map(executable.with_suffix, unique)
 
-    if os.path.isfile(executable):
-        return executable
 
+def _search_paths(path):
     if path is None:
         path = os.environ.get('PATH', None)
         if path is None:
@@ -94,12 +96,23 @@ def find_executable(executable, path=None):
 
     # PATH='' doesn't match, whereas PATH=':' looks in the current directory
     if not path:
-        return None
-
-    paths = path.split(os.pathsep)
-    for p in paths:
-        f = os.path.join(p, executable)
-        if os.path.isfile(f):
-            # the file exists, we have a shot at spawn working
-            return f
-    return None
+        return ()
+
+    return map(pathlib.Path, path.split(os.pathsep))
+
+
+def find_executable(executable, path=None):
+    """Tries to find 'executable' in the directories listed in 'path'.
+
+    A string listing directories separated by 'os.pathsep'; defaults to
+    os.environ['PATH'].  Returns the complete filename or None if not found.
+    """
+    if os.path.isfile(executable):
+        return executable
+
+    found = (
+        os.fspath(exe)
+        for p in _search_paths(path)
+        for exe in filter(pathlib.Path.is_file, _executable_candidates(p / executable))
+    )
+    return next(found, None)

distutils/tests/test_spawn.py

@@ -1,6 +1,8 @@
 """Tests for distutils.spawn."""
 
 import os
+import platform
+import random
 import stat
 import sys
 import unittest.mock as mock
@@ -45,25 +47,20 @@ def test_spawn(self):
         spawn([exe])  # should work without any error
 
     def test_find_executable(self, tmp_path):
-        program_noeext = 'program'
-        # Give the temporary program an ".exe" suffix for all.
-        # It's needed on Windows and not harmful on other platforms.
-        program = program_noeext + ".exe"
-
-        program_path = tmp_path / program
-        program_path.write_text("", encoding='utf-8')
-        program_path.chmod(stat.S_IXUSR)
+        program_path = self._make_executable(tmp_path, '.exe')
+        program = program_path.name
+        program_noeext = program_path.with_suffix('').name
         filename = str(program_path)
         tmp_dir = path.Path(tmp_path)
 
         # test path parameter
         rv = find_executable(program, path=tmp_dir)
         assert rv == filename
 
-        if sys.platform == 'win32':
+        if sys.platform == 'win32':  # pragma: no cover
             # test without ".exe" extension
             rv = find_executable(program_noeext, path=tmp_dir)
-            assert rv == filename
+            assert os.path.samefile(rv, filename)
 
         # test find in the current directory
         with tmp_dir:
@@ -121,7 +118,49 @@ def test_find_executable(self, tmp_path):
                 rv = find_executable(program)
                 assert rv == filename
 
+    def test_find_executable_alt_ext(self, tmp_path, windows_pathext):
+        """
+        On Windows with PATHEXT set, also executables matching those.
+        """
+        ext = random.choice(os.environ['PATHEXT'].split(os.pathsep))
+        program = self._make_executable(tmp_path, ext)
+        rv = find_executable(program.with_suffix('').name, path=str(tmp_path))
+        assert rv == str(program)
+
+    @staticmethod
+    def _make_executable(tmp_path, ext):
+        # Give the temporary program a suffix regardless of platform.
+        # It's needed on Windows and not harmful on others.
+        program = tmp_path.joinpath('program').with_suffix(ext)
+        program.write_text("", encoding='utf-8')
+        program.chmod(stat.S_IXUSR)
+        return program
+
     def test_spawn_missing_exe(self):
         with pytest.raises(DistutilsExecError) as ctx:
             spawn(['does-not-exist'])
         assert "command 'does-not-exist' failed" in str(ctx.value)
+
+
+@pytest.fixture
+def windows_pathext(monkeypatch):
+    """
+    Set PATHEXT as if on Windows.
+    """
+    monkeypatch.setattr(platform, 'system', lambda: 'Windows')
+    typical_exts = [
+        '.COM',
+        '.EXE',
+        '.BAT',
+        '.CMD',
+        '.VBS',
+        '.VBE',
+        '.JS',
+        '.JSE',
+        '.WSF',
+        '.WSH',
+        '.MSC',
+        '.PY',
+        '.PYW',
+    ]
+    monkeypatch.setenv('PATHEXT', os.pathsep.join(typical_exts))