Implement a simplified xargs in python

tests/languages/helpers_test.py

@@ -1,16 +0,0 @@
-from __future__ import absolute_import
-from __future__ import unicode_literals
-
-from pre_commit.languages.helpers import file_args_to_stdin
-
-
-def test_file_args_to_stdin_empty():
-    assert file_args_to_stdin([]) == ''
-
-
-def test_file_args_to_stdin_some():
-    assert file_args_to_stdin(['foo', 'bar']) == 'foo\0bar\0'
-
-
-def test_file_args_to_stdin_tuple():
-    assert file_args_to_stdin(('foo', 'bar')) == 'foo\0bar\0'

tests/repository_test.py

@@ -234,13 +234,13 @@ def test_pcre_hook_matching(tempdir_factory, store):
         _test_hook_repo(
             tempdir_factory, store, 'pcre_hooks_repo',
             'regex-with-quotes', ['herp', 'derp'], b"herp:2:herpfoo'bard\n",
-            expected_return_code=123,
+            expected_return_code=1,
         )
 
         _test_hook_repo(
             tempdir_factory, store, 'pcre_hooks_repo',
             'other-regex', ['herp', 'derp'], b'derp:1:[INFO] information yo\n',
-            expected_return_code=123,
+            expected_return_code=1,
         )
 
 
@@ -255,7 +255,7 @@ def test_pcre_hook_case_insensitive_option(tempdir_factory, store):
         _test_hook_repo(
             tempdir_factory, store, 'pcre_hooks_repo',
             'regex-with-grep-args', ['herp'], b'herp:1:FoOoOoObar\n',
-            expected_return_code=123,
+            expected_return_code=1,
         )
 
 
@@ -264,7 +264,7 @@ def test_pcre_hook_case_insensitive_option(tempdir_factory, store):
 def test_pcre_many_files(tempdir_factory, store):
     # This is intended to simulate lots of passing files and one failing file
     # to make sure it still fails.  This is not the case when naively using
-    # a system hook with `grep -H -n '...'` and expected_return_code=123.
+    # a system hook with `grep -H -n '...'` and expected_return_code=1.
     path = git_dir(tempdir_factory)
     with cwd(path):
         with io.open('herp', 'w') as herp:
@@ -275,7 +275,7 @@ def test_pcre_many_files(tempdir_factory, store):
             'other-regex',
             ['/dev/null'] * 15000 + ['herp'],
             b'herp:1:[INFO] info\n',
-            expected_return_code=123,
+            expected_return_code=1,
         )
 
 
@@ -355,7 +355,7 @@ def test_additional_python_dependencies_installed(tempdir_factory, store):
     config = make_config_from_repo(path)
     config['hooks'][0]['additional_dependencies'] = ['mccabe']
     repo = Repository.create(config, store)
-    repo.run_hook(repo.hooks[0][1], [])
+    repo.require_installed()
     with python.in_env(repo.cmd_runner, 'default'):
         output = cmd_output('pip', 'freeze', '-l')[1]
         assert 'mccabe' in output
@@ -367,11 +367,11 @@ def test_additional_dependencies_roll_forward(tempdir_factory, store):
     config = make_config_from_repo(path)
     # Run the repo once without additional_dependencies
     repo = Repository.create(config, store)
-    repo.run_hook(repo.hooks[0][1], [])
+    repo.require_installed()
     # Now run it with additional_dependencies
     config['hooks'][0]['additional_dependencies'] = ['mccabe']
     repo = Repository.create(config, store)
-    repo.run_hook(repo.hooks[0][1], [])
+    repo.require_installed()
     # We should see our additional dependency installed
     with python.in_env(repo.cmd_runner, 'default'):
         output = cmd_output('pip', 'freeze', '-l')[1]
@@ -388,7 +388,7 @@ def test_additional_ruby_dependencies_installed(
     config = make_config_from_repo(path)
     config['hooks'][0]['additional_dependencies'] = ['thread_safe']
     repo = Repository.create(config, store)
-    repo.run_hook(repo.hooks[0][1], [])
+    repo.require_installed()
     with ruby.in_env(repo.cmd_runner, 'default'):
         output = cmd_output('gem', 'list', '--local')[1]
         assert 'thread_safe' in output
@@ -405,7 +405,7 @@ def test_additional_node_dependencies_installed(
     # Careful to choose a small package that's not depped by npm
     config['hooks'][0]['additional_dependencies'] = ['lodash']
     repo = Repository.create(config, store)
-    repo.run_hook(repo.hooks[0][1], [])
+    repo.require_installed()
     with node.in_env(repo.cmd_runner, 'default'):
         cmd_output('npm', 'config', 'set', 'global', 'true')
         output = cmd_output('npm', 'ls')[1]

tests/xargs_test.py

@@ -0,0 +1,47 @@
+from __future__ import absolute_import
+from __future__ import unicode_literals
+
+import pytest
+
+from pre_commit import xargs
+
+
+def test_partition_trivial():
+    assert xargs.partition(('cmd',), ()) == (('cmd',),)
+
+
+def test_partition_simple():
+    assert xargs.partition(('cmd',), ('foo',)) == (('cmd', 'foo'),)
+
+
+def test_partition_limits():
+    ret = xargs.partition(
+        ('ninechars',), (
+            # Just match the end (with spaces)
+            '.' * 5, '.' * 4,
+            # Just match the end (single arg)
+            '.' * 10,
+            # Goes over the end
+            '.' * 5,
+            '.' * 6,
+        ),
+        _max_length=20,
+    )
+    assert ret == (
+        ('ninechars', '.' * 5, '.' * 4),
+        ('ninechars', '.' * 10),
+        ('ninechars', '.' * 5),
+        ('ninechars', '.' * 6),
+    )
+
+
+def test_argument_too_long():
+    with pytest.raises(xargs.ArgumentTooLongError):
+        xargs.partition(('a' * 5,), ('a' * 5,), _max_length=10)
+
+
+def test_xargs_smoke():
+    ret, out, err = xargs.xargs(('echo',), ('hello', 'world'))
+    assert ret == 0
+    assert out == b'hello world\n'
+    assert err == b''