Merge pull request #674 from pre-commit/simpler_cross_version_tests

Simplify cross version tests

.travis.yml

@@ -16,8 +16,6 @@ matrix:
 install: pip install coveralls tox
 script: tox
 before_install:
-    # work around https://github.com/travis-ci/travis-ci/issues/8363
-    - which python3.5 || (pyenv install 3.5.4 && pyenv global system 3.5.4)
     - git --version
     - |
         if [ "$LATEST_GIT" = "1" ]; then

CONTRIBUTING.md

@@ -5,9 +5,8 @@
 - The complete test suite depends on having at least the following installed (possibly not
   a complete list)
   - git (A sufficiently newer version is required to run pre-push tests)
-  - python
+  - python2 (Required by a test which checks different python versions)
-  - python3.4 (Required by a test which checks different python versions)
+  - python3 (Required by a test which checks different python versions)
-  - python3.5 (Required by a test which checks different python versions)
   - tox (or virtualenv)
   - ruby + gem
   - docker

pre_commit/languages/python.py

@@ -9,6 +9,7 @@ from pre_commit.envcontext import UNSET
 from pre_commit.envcontext import Var
 from pre_commit.languages import helpers
 from pre_commit.parse_shebang import find_executable
+from pre_commit.util import CalledProcessError
 from pre_commit.util import clean_path_on_failure
 from pre_commit.util import cmd_output
 from pre_commit.xargs import xargs
@@ -40,6 +41,17 @@ def in_env(repo_cmd_runner, language_version):
         yield
 
 
+def _find_by_py_launcher(version):  # pragma: no cover (windows only)
+    if version.startswith('python'):
+        try:
+            return cmd_output(
+                'py', '-{}'.format(version[len('python'):]),
+                '-c', 'import sys; print(sys.executable)',
+            )[1].strip()
+        except CalledProcessError:
+            pass
+
+
 def _get_default_version():  # pragma: no cover (platform dependent)
     def _norm(path):
         _, exe = os.path.split(path.lower())
@@ -66,6 +78,9 @@ def _get_default_version():  # pragma: no cover (platform dependent)
     if find_executable(exe):
         return exe
 
+    if _find_by_py_launcher(exe):
+        return exe
+
     # Give a best-effort try for windows
     if os.path.exists(r'C:\{}\python.exe'.format(exe.replace('.', ''))):
         return exe
@@ -99,6 +114,10 @@ def norm_version(version):
         if version_exec and version_exec != version:
             return version_exec
 
+        version_exec = _find_by_py_launcher(version)
+        if version_exec:
+            return version_exec
+
         # If it is in the form pythonx.x search in the default
         # place on windows
         if version.startswith('python'):

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

@@ -2,5 +2,5 @@
     name: Python 3 Hook
     entry: python3-hook
     language: python
-    language_version: python3.5
+    language_version: python3
     files: \.py$

testing/resources/python3_hooks_repo/.pre-commit-hooks.yaml

@@ -2,5 +2,5 @@
     name: Python 3 Hook
     entry: python3-hook
     language: python
-    language_version: python3.5
+    language_version: python3
     files: \.py$

testing/resources/python3_hooks_repo/python3_hook/main.py

@@ -4,7 +4,7 @@ import sys
 
 
 def func():
-    print('{}.{}'.format(*sys.version_info[:2]))
+    print(sys.version_info[0])
     print(repr(sys.argv[1:]))
     print('Hello World')
     return 0

tests/repository_test.py

@@ -130,8 +130,8 @@ def test_switch_language_versions_doesnt_clobber(tempdir_factory, store):
         assert ret[0] == 0
         assert _norm_out(ret[1]) == expected_output
 
-    run_on_version('python3.4', b'3.4\n[]\nHello World\n')
+    run_on_version('python2', b'2\n[]\nHello World\n')
-    run_on_version('python3.5', b'3.5\n[]\nHello World\n')
+    run_on_version('python3', b'3\n[]\nHello World\n')
 
 
 @pytest.mark.integration
@@ -140,7 +140,7 @@ def test_versioned_python_hook(tempdir_factory, store):
         tempdir_factory, store, 'python3_hooks_repo',
         'python3-hook',
         [os.devnull],
-        b"3.5\n['" + five.to_bytes(os.devnull) + b"']\nHello World\n",
+        b"3\n['" + five.to_bytes(os.devnull) + b"']\nHello World\n",
     )