From 51248d172719fa83e0108205f14caece12cf2ae2 Mon Sep 17 00:00:00 2001
From: Daniel Porter <dpreid@gmail.com>
Date: Wed, 24 Apr 2024 12:25:30 +0100
Subject: [PATCH] Use cpanminus if available for perl pre-commit dependencies

cpanminus is broadly compatible with our syntax use of cpan, but can
offer additional benefits such as Pkg::Name@Version definitions, as well
as built-in modules to reduce the environment requirements on the system
when resolving dependencies.

Tests have been updated to ensure functionality works with either
utility.
---
 pre_commit/languages/perl.py | 13 ++++++++++---
 tests/languages/perl_test.py | 10 +++++++++-
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/pre_commit/languages/perl.py b/pre_commit/languages/perl.py
index 61b1d114..42b800fe 100644
--- a/pre_commit/languages/perl.py
+++ b/pre_commit/languages/perl.py
@@ -45,6 +45,13 @@ def install_environment(
     lang_base.assert_version_default('perl', version)
 
     with in_env(prefix, version):
-        lang_base.setup_cmd(
-            prefix, ('cpan', '-T', '.', *additional_dependencies),
-        )
+        if lang_base.exe_exists('cpanm'):
+            lang_base.setup_cmd(
+                prefix,
+                ('cpanm', '.', *additional_dependencies),
+            )
+        else:
+            lang_base.setup_cmd(
+                prefix,
+                ('cpan', '-T', '.', *additional_dependencies),
+            )
diff --git a/tests/languages/perl_test.py b/tests/languages/perl_test.py
index 042478db..cac24c61 100644
--- a/tests/languages/perl_test.py
+++ b/tests/languages/perl_test.py
@@ -1,5 +1,9 @@
 from __future__ import annotations
 
+from unittest.mock import patch
+
+import pytest
+
 from pre_commit.languages import perl
 from pre_commit.store import _make_local_repo
 from pre_commit.util import make_executable
@@ -56,7 +60,10 @@ sub hello {
     assert ret == (0, b'Hello from perl-commit Perl!\n')
 
 
-def test_perl_additional_dependencies(tmp_path):
+@pytest.mark.parametrize('cpanm', [True, False])
+@patch('pre_commit.lang_base.exe_exists')
+def test_perl_additional_dependencies(mock_exe_exists, cpanm, tmp_path):
+    mock_exe_exists.return_value = cpanm
     _make_local_repo(str(tmp_path))
 
     ret, out = run_language(
@@ -65,5 +72,6 @@ def test_perl_additional_dependencies(tmp_path):
         'perltidy --version',
         deps=('SHANCOCK/Perl-Tidy-20211029.tar.gz',),
     )
+    mock_exe_exists.assert_called_once_with('cpanm')
     assert ret == 0
     assert out.startswith(b'This is perltidy, v20211029')