Merge pull request #1388 from pre-commit/node_default_system

Default to `language_version: system` if node and npm are installed

.pre-commit-config.yaml

@@ -17,34 +17,34 @@ repos:
     -   id: flake8
         additional_dependencies: [flake8-typing-imports==1.6.0]
 -   repo: https://github.com/pre-commit/mirrors-autopep8
-    rev: v1.5
+    rev: v1.5.1
     hooks:
     -   id: autopep8
 -   repo: https://github.com/pre-commit/pre-commit
-    rev: v2.1.1
+    rev: v2.2.0
     hooks:
     -   id: validate_manifest
 -   repo: https://github.com/asottile/pyupgrade
-    rev: v2.0.1
+    rev: v2.1.0
     hooks:
     -   id: pyupgrade
         args: [--py36-plus]
 -   repo: https://github.com/asottile/reorder_python_imports
-    rev: v1.9.0
+    rev: v2.1.0
     hooks:
     -   id: reorder-python-imports
         args: [--py3-plus]
 -   repo: https://github.com/asottile/add-trailing-comma
-    rev: v1.5.0
+    rev: v2.0.1
     hooks:
     -   id: add-trailing-comma
         args: [--py36-plus]
 -   repo: https://github.com/asottile/setup-cfg-fmt
-    rev: v1.6.0
+    rev: v1.8.2
     hooks:
     -   id: setup-cfg-fmt
 -   repo: https://github.com/pre-commit/mirrors-mypy
-    rev: v0.761
+    rev: v0.770
     hooks:
     -   id: mypy
         exclude: ^testing/resources/

pre_commit/languages/node.py

@@ -1,4 +1,5 @@
 import contextlib
+import functools
 import os
 import sys
 from typing import Generator
@@ -6,6 +7,7 @@ from typing import Sequence
 from typing import Tuple
 
 import pre_commit.constants as C
+from pre_commit import parse_shebang
 from pre_commit.envcontext import envcontext
 from pre_commit.envcontext import PatchesT
 from pre_commit.envcontext import Var
@@ -18,10 +20,22 @@ from pre_commit.util import cmd_output
 from pre_commit.util import cmd_output_b
 
 ENVIRONMENT_DIR = 'node_env'
-get_default_version = helpers.basic_get_default_version
 healthy = helpers.basic_healthy
 
 
+@functools.lru_cache(maxsize=1)
+def get_default_version() -> str:
+    # nodeenv does not yet support `-n system` on windows
+    if sys.platform == 'win32':
+        return C.DEFAULT
+    # if node is already installed, we can save a bunch of setup time by
+    # using the installed version
+    elif all(parse_shebang.find_executable(exe) for exe in ('node', 'npm')):
+        return 'system'
+    else:
+        return C.DEFAULT
+
+
 def _envdir(prefix: Prefix, version: str) -> str:
     directory = helpers.environment_dir(ENVIRONMENT_DIR, version)
     return prefix.path(directory)

tests/languages/node_test.py

@@ -0,0 +1,47 @@
+import sys
+from unittest import mock
+
+import pytest
+
+import pre_commit.constants as C
+from pre_commit import parse_shebang
+from pre_commit.languages.node import get_default_version
+
+
+ACTUAL_GET_DEFAULT_VERSION = get_default_version.__wrapped__
+
+
+@pytest.fixture
+def is_linux():
+    with mock.patch.object(sys, 'platform', 'linux'):
+        yield
+
+
+@pytest.fixture
+def is_win32():
+    with mock.patch.object(sys, 'platform', 'win32'):
+        yield
+
+
+@pytest.fixture
+def find_exe_mck():
+    with mock.patch.object(parse_shebang, 'find_executable') as mck:
+        yield mck
+
+
+@pytest.mark.usefixtures('is_linux')
+def test_sets_system_when_node_and_npm_are_available(find_exe_mck):
+    find_exe_mck.return_value = '/path/to/exe'
+    assert ACTUAL_GET_DEFAULT_VERSION() == 'system'
+
+
+@pytest.mark.usefixtures('is_linux')
+def test_uses_default_when_node_and_npm_are_not_available(find_exe_mck):
+    find_exe_mck.return_value = None
+    assert ACTUAL_GET_DEFAULT_VERSION() == C.DEFAULT
+
+
+@pytest.mark.usefixtures('is_win32')
+def test_sets_default_on_windows(find_exe_mck):
+    find_exe_mck.return_value = '/path/to/exe'
+    assert ACTUAL_GET_DEFAULT_VERSION() == C.DEFAULT

tests/repository_test.py

@@ -131,9 +131,9 @@ def test_python_hook(tempdir_factory, store):
 def test_python_hook_default_version(tempdir_factory, store):
     # make sure that this continues to work for platforms where default
     # language detection does not work
-    with mock.patch.object(
+    returns_default = mock.Mock(return_value=C.DEFAULT)
-            python, 'get_default_version', return_value=C.DEFAULT,
+    lang = languages['python']._replace(get_default_version=returns_default)
-    ):
+    with mock.patch.dict(languages, python=lang):
         test_python_hook(tempdir_factory, store)
 
 
@@ -243,6 +243,15 @@ def test_run_a_node_hook(tempdir_factory, store):
     )
 
 
+def test_run_a_node_hook_default_version(tempdir_factory, store):
+    # make sure that this continues to work for platforms where node is not
+    # installed at the system
+    returns_default = mock.Mock(return_value=C.DEFAULT)
+    lang = languages['node']._replace(get_default_version=returns_default)
+    with mock.patch.dict(languages, node=lang):
+        test_run_a_node_hook(tempdir_factory, store)
+
+
 def test_run_versioned_node_hook(tempdir_factory, store):
     _test_hook_repo(
         tempdir_factory, store, 'node_versioned_hooks_repo',