Add utility for parsing shebangs and resolving PATH

tests/commands/install_uninstall_test.py

@@ -15,12 +15,12 @@ from pre_commit.commands.install_uninstall import IDENTIFYING_HASH
 from pre_commit.commands.install_uninstall import install
 from pre_commit.commands.install_uninstall import is_our_pre_commit
 from pre_commit.commands.install_uninstall import is_previous_pre_commit
-from pre_commit.commands.install_uninstall import make_executable
 from pre_commit.commands.install_uninstall import PREVIOUS_IDENTIFYING_HASHES
 from pre_commit.commands.install_uninstall import uninstall
 from pre_commit.runner import Runner
 from pre_commit.util import cmd_output
 from pre_commit.util import cwd
+from pre_commit.util import make_executable
 from pre_commit.util import mkdirp
 from pre_commit.util import resource_filename
 from testing.fixtures import git_dir
@@ -473,6 +473,8 @@ def test_installed_from_venv(tempdir_factory):
                 'TERM': os.environ.get('TERM', ''),
                 # Windows needs this to import `random`
                 'SYSTEMROOT': os.environ.get('SYSTEMROOT', ''),
+                # Windows needs this to resolve executables
+                'PATHEXT': os.environ.get('PATHEXT', ''),
             },
         )
         assert ret == 0

tests/parse_shebang_test.py

@@ -0,0 +1,154 @@
+from __future__ import absolute_import
+from __future__ import unicode_literals
+
+import contextlib
+import distutils.spawn
+import io
+import os
+import sys
+
+import pytest
+
+from pre_commit import parse_shebang
+from pre_commit.envcontext import envcontext
+from pre_commit.envcontext import Var
+from pre_commit.util import make_executable
+
+
+@pytest.mark.parametrize(
+    ('s', 'expected'),
+    (
+        (b'', ()),
+        (b'#!/usr/bin/python', ('/usr/bin/python',)),
+        (b'#!/usr/bin/env python', ('python',)),
+        (b'#! /usr/bin/python', ('/usr/bin/python',)),
+        (b'#!/usr/bin/foo  python', ('/usr/bin/foo', 'python')),
+        (b'\xf9\x93\x01\x42\xcd', ()),
+        (b'#!\xf9\x93\x01\x42\xcd', ()),
+        (b'#!\x00\x00\x00\x00', ()),
+    ),
+)
+def test_parse_bytesio(s, expected):
+    assert parse_shebang.parse_bytesio(io.BytesIO(s)) == expected
+
+
+def test_file_doesnt_exist():
+    assert parse_shebang.parse_filename('herp derp derp') == ()
+
+
+@pytest.mark.xfail(
+    sys.platform == 'win32', reason='Windows says everything is X_OK',
+)
+def test_file_not_executable(tmpdir):
+    x = tmpdir.join('f')
+    x.write_text('#!/usr/bin/env python', encoding='UTF-8')
+    assert parse_shebang.parse_filename(x.strpath) == ()
+
+
+def test_simple_case(tmpdir):
+    x = tmpdir.join('f')
+    x.write_text('#!/usr/bin/env python', encoding='UTF-8')
+    make_executable(x.strpath)
+    assert parse_shebang.parse_filename(x.strpath) == ('python',)
+
+
+def test_find_executable_full_path():
+    assert parse_shebang.find_executable(sys.executable) == sys.executable
+
+
+def test_find_executable_on_path():
+    expected = distutils.spawn.find_executable('echo')
+    assert parse_shebang.find_executable('echo') == expected
+
+
+def test_find_executable_not_found_none():
+    assert parse_shebang.find_executable('not-a-real-executable') is None
+
+
+def write_executable(shebang, filename='run'):
+    os.mkdir('bin')
+    path = os.path.join('bin', filename)
+    with io.open(path, 'w') as f:
+        f.write('#!{0}'.format(shebang))
+    make_executable(path)
+    return path
+
+
+@contextlib.contextmanager
+def bin_on_path():
+    bindir = os.path.join(os.getcwd(), 'bin')
+    with envcontext((('PATH', (bindir, os.pathsep, Var('PATH'))),)):
+        yield
+
+
+def test_find_executable_path_added(in_tmpdir):
+    path = os.path.abspath(write_executable('/usr/bin/env sh'))
+    assert parse_shebang.find_executable('run') is None
+    with bin_on_path():
+        assert parse_shebang.find_executable('run') == path
+
+
+def test_find_executable_path_ext(in_tmpdir):
+    """Windows exports PATHEXT as a list of extensions to automatically add
+    to executables when doing PATH searching.
+    """
+    exe_path = os.path.abspath(write_executable(
+        '/usr/bin/env sh', filename='run.myext',
+    ))
+    env_path = {'PATH': os.path.dirname(exe_path)}
+    env_path_ext = dict(env_path, PATHEXT=os.pathsep.join(('.exe', '.myext')))
+    assert parse_shebang.find_executable('run') is None
+    assert parse_shebang.find_executable('run', _environ=env_path) is None
+    ret = parse_shebang.find_executable('run.myext', _environ=env_path)
+    assert ret == exe_path
+    ret = parse_shebang.find_executable('run', _environ=env_path_ext)
+    assert ret == exe_path
+
+
+def test_normexe_does_not_exist():
+    with pytest.raises(OSError) as excinfo:
+        parse_shebang.normexe('i-dont-exist-lol')
+    assert excinfo.value.args == ('Executable i-dont-exist-lol not found',)
+
+
+def test_normexe_already_full_path():
+    assert parse_shebang.normexe(sys.executable) == sys.executable
+
+
+def test_normexe_gives_full_path():
+    expected = distutils.spawn.find_executable('echo')
+    assert parse_shebang.normexe('echo') == expected
+    assert os.sep in expected
+
+
+def test_normalize_cmd_trivial():
+    cmd = (distutils.spawn.find_executable('echo'), 'hi')
+    assert parse_shebang.normalize_cmd(cmd) == cmd
+
+
+def test_normalize_cmd_PATH():
+    cmd = ('python', '--version')
+    expected = (distutils.spawn.find_executable('python'), '--version')
+    assert parse_shebang.normalize_cmd(cmd) == expected
+
+
+def test_normalize_cmd_shebang(in_tmpdir):
+    python = distutils.spawn.find_executable('python')
+    path = write_executable(python.replace(os.sep, '/'))
+    assert parse_shebang.normalize_cmd((path,)) == (python, path)
+
+
+def test_normalize_cmd_PATH_shebang_full_path(in_tmpdir):
+    python = distutils.spawn.find_executable('python')
+    path = write_executable(python.replace(os.sep, '/'))
+    with bin_on_path():
+        ret = parse_shebang.normalize_cmd(('run',))
+        assert ret == (python, os.path.abspath(path))
+
+
+def test_normalize_cmd_PATH_shebang_PATH(in_tmpdir):
+    python = distutils.spawn.find_executable('python')
+    path = write_executable('/usr/bin/env python')
+    with bin_on_path():
+        ret = parse_shebang.normalize_cmd(('run',))
+        assert ret == (python, os.path.abspath(path))

tests/prefixed_command_runner_test.py

@@ -78,7 +78,7 @@ def test_run_substitutes_prefix(popen_mock, makedirs_mock):
     )
     ret = instance.run(['{prefix}bar', 'baz'], retcode=None)
     popen_mock.assert_called_once_with(
-        [five.n(os.path.join('prefix', 'bar')), five.n('baz')],
+        (five.n(os.path.join('prefix', 'bar')), five.n('baz')),
         env=None,
         stdin=subprocess.PIPE,
         stdout=subprocess.PIPE,
@@ -132,4 +132,4 @@ def test_raises_on_error(popen_mock, makedirs_mock):
         instance = PrefixedCommandRunner(
             '.', popen=popen_mock, makedirs=makedirs_mock,
         )
-        instance.run(['foo'])
+        instance.run(['echo'])