add initial dotnet support

pre_commit/languages/all.py

@@ -8,6 +8,7 @@ from pre_commit.hook import Hook
 from pre_commit.languages import conda
 from pre_commit.languages import docker
 from pre_commit.languages import docker_image
+from pre_commit.languages import dotnet
 from pre_commit.languages import fail
 from pre_commit.languages import golang
 from pre_commit.languages import node
@@ -42,6 +43,7 @@ languages = {
     'conda': Language(name='conda', ENVIRONMENT_DIR=conda.ENVIRONMENT_DIR, get_default_version=conda.get_default_version, healthy=conda.healthy, install_environment=conda.install_environment, run_hook=conda.run_hook),  # noqa: E501
     'docker': Language(name='docker', ENVIRONMENT_DIR=docker.ENVIRONMENT_DIR, get_default_version=docker.get_default_version, healthy=docker.healthy, install_environment=docker.install_environment, run_hook=docker.run_hook),  # noqa: E501
     'docker_image': Language(name='docker_image', ENVIRONMENT_DIR=docker_image.ENVIRONMENT_DIR, get_default_version=docker_image.get_default_version, healthy=docker_image.healthy, install_environment=docker_image.install_environment, run_hook=docker_image.run_hook),  # noqa: E501
+    'dotnet': Language(name='dotnet', ENVIRONMENT_DIR=dotnet.ENVIRONMENT_DIR, get_default_version=dotnet.get_default_version, healthy=dotnet.healthy, install_environment=dotnet.install_environment, run_hook=dotnet.run_hook),  # noqa: E501
     'fail': Language(name='fail', ENVIRONMENT_DIR=fail.ENVIRONMENT_DIR, get_default_version=fail.get_default_version, healthy=fail.healthy, install_environment=fail.install_environment, run_hook=fail.run_hook),  # noqa: E501
     'golang': Language(name='golang', ENVIRONMENT_DIR=golang.ENVIRONMENT_DIR, get_default_version=golang.get_default_version, healthy=golang.healthy, install_environment=golang.install_environment, run_hook=golang.run_hook),  # noqa: E501
     'node': Language(name='node', ENVIRONMENT_DIR=node.ENVIRONMENT_DIR, get_default_version=node.get_default_version, healthy=node.healthy, install_environment=node.install_environment, run_hook=node.run_hook),  # noqa: E501

pre_commit/languages/dotnet.py

@@ -0,0 +1,90 @@
+import contextlib
+import os.path
+from typing import Generator
+from typing import Sequence
+from typing import Tuple
+
+import pre_commit.constants as C
+from pre_commit.envcontext import envcontext
+from pre_commit.envcontext import PatchesT
+from pre_commit.envcontext import Var
+from pre_commit.hook import Hook
+from pre_commit.languages import helpers
+from pre_commit.prefix import Prefix
+from pre_commit.util import clean_path_on_failure
+from pre_commit.util import rmtree
+
+ENVIRONMENT_DIR = 'dotnetenv'
+BIN_DIR = 'bin'
+
+get_default_version = helpers.basic_get_default_version
+healthy = helpers.basic_healthy
+
+
+def get_env_patch(venv: str) -> PatchesT:
+    return (
+        ('PATH', (os.path.join(venv, BIN_DIR), os.pathsep, Var('PATH'))),
+    )
+
+
+@contextlib.contextmanager
+def in_env(prefix: Prefix) -> Generator[None, None, None]:
+    directory = helpers.environment_dir(ENVIRONMENT_DIR, C.DEFAULT)
+    envdir = prefix.path(directory)
+    with envcontext(get_env_patch(envdir)):
+        yield
+
+
+def install_environment(
+        prefix: Prefix,
+        version: str,
+        additional_dependencies: Sequence[str],
+) -> None:
+    helpers.assert_version_default('dotnet', version)
+    helpers.assert_no_additional_deps('dotnet', additional_dependencies)
+
+    envdir = prefix.path(helpers.environment_dir(ENVIRONMENT_DIR, version))
+    with clean_path_on_failure(envdir):
+        build_dir = 'pre-commit-build'
+
+        # Build & pack nupkg file
+        helpers.run_setup_cmd(
+            prefix,
+            (
+                'dotnet', 'pack',
+                '--configuration', 'Release',
+                '--output', build_dir,
+            ),
+        )
+
+        # Determine tool from the packaged file <tool_name>.<version>.nupkg
+        build_outputs = os.listdir(os.path.join(prefix.prefix_dir, build_dir))
+        if len(build_outputs) != 1:
+            raise NotImplementedError(
+                f"Can't handle multiple build outputs. Got {build_outputs}",
+            )
+        tool_name = build_outputs[0].split('.')[0]
+
+        # Install to bin dir
+        helpers.run_setup_cmd(
+            prefix,
+            (
+                'dotnet', 'tool', 'install',
+                '--tool-path', os.path.join(envdir, BIN_DIR),
+                '--add-source', build_dir,
+                tool_name,
+            ),
+        )
+
+        # Cleanup build output
+        for d in ('bin', 'obj', build_dir):
+            rmtree(prefix.path(d))
+
+
+def run_hook(
+        hook: Hook,
+        file_args: Sequence[str],
+        color: bool,
+) -> Tuple[int, bytes]:
+    with in_env(hook.prefix):
+        return helpers.run_xargs(hook, hook.cmd, file_args, color=color)