Fix test since pip 10 changed output

testing/resources/not_installable_repo/.pre-commit-hooks.yaml

@@ -1,6 +0,0 @@
--   id: foo
-    name: Foo
-    entry: foo
-    language: python
-    language_version: python2.7
-    files: \.py$

testing/resources/not_installable_repo/setup.py

@@ -1,17 +0,0 @@
-# -*- coding: utf-8 -*-
-from __future__ import print_function
-from __future__ import unicode_literals
-
-import sys
-
-
-def main():
-    # Intentionally write mixed encoding to the output.  This should not crash
-    # pre-commit and should write bytes to the output.
-    sys.stderr.write('☃'.encode('UTF-8') + '²'.encode('latin1') + b'\n')
-    # Return 1 to indicate failures
-    return 1
-
-
-if __name__ == '__main__':
-    exit(main())

tests/commands/run_test.py

@@ -479,31 +479,6 @@ def test_stdout_write_bug_py26(
         assert 'UnicodeDecodeError' not in stdout
 
 
-def test_hook_install_failure(mock_out_store_directory, tempdir_factory):
-    git_path = make_consuming_repo(tempdir_factory, 'not_installable_repo')
-    with cwd(git_path):
-        install(Runner(git_path, C.CONFIG_FILE))
-
-        _, stdout, _ = cmd_output_mocked_pre_commit_home(
-            'git', 'commit', '-m', 'Commit!',
-            # git commit puts pre-commit to stderr
-            stderr=subprocess.STDOUT,
-            retcode=None,
-            encoding=None,
-            tempdir_factory=tempdir_factory,
-        )
-        assert b'UnicodeDecodeError' not in stdout
-        # Doesn't actually happen, but a reasonable assertion
-        assert b'UnicodeEncodeError' not in stdout
-
-        # Sanity check our output
-        assert (
-            b'An unexpected error has occurred: CalledProcessError: ' in
-            stdout
-        )
-        assert '☃'.encode('UTF-8') + '²'.encode('latin1') in stdout
-
-
 def test_lots_of_files(mock_out_store_directory, tempdir_factory):
     # windows xargs seems to have a bug, here's a regression test for
     # our workaround

tests/languages/helpers_test.py

@@ -1,7 +1,13 @@
 from __future__ import absolute_import
 from __future__ import unicode_literals
 
+import sys
+
+import pytest
+
 from pre_commit.languages import helpers
+from pre_commit.prefix import Prefix
+from pre_commit.util import CalledProcessError
 
 
 def test_basic_get_default_version():
@@ -10,3 +16,15 @@ def test_basic_get_default_version():
 
 def test_basic_healthy():
     assert helpers.basic_healthy(None, None) is True
+
+
+def test_failed_setup_command_does_not_unicode_error():
+    script = (
+        'import sys\n'
+        "getattr(sys.stderr, 'buffer', sys.stderr).write(b'\\x81\\xfe')\n"
+        'exit(1)\n'
+    )
+
+    # an assertion that this does not raise `UnicodeError`
+    with pytest.raises(CalledProcessError):
+        helpers.run_setup_cmd(Prefix('.'), (sys.executable, '-c', script))