Support custom hooks directory

Git supports the `core.hooksPath` configuration setting as of Git 2.9.
Use it when installing hooks if it is defined.

Closes #447

Author: sds

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## master
 
 * Add [`hadolint`](https://github.com/lukasmartinelli/hadolint) pre-commit hook
+* Use the `core.hooksPath` Git configuration option when installing hooks
 
 ## 0.39.1
 

lib/overcommit/git_config.rb

@@ -1,3 +1,5 @@
+require 'overcommit/utils'
+
 module Overcommit
   # Get configuration options from git
   module GitConfig
@@ -8,5 +10,11 @@ def comment_character
       char = '#' if char == ''
       char
     end
+
+    def hooks_path
+      path = `git config --get core.hooksPath`.chomp
+      return File.join(Overcommit::Utils.repo_root, '.git', 'hooks') if path.empty?
+      File.absolute_path(path)
+    end
   end
 end

lib/overcommit/installer.rb

@@ -65,8 +65,7 @@ def update
     end
 
     def hooks_path
-      absolute_target = File.expand_path(@target)
-      File.join(Overcommit::Utils.git_dir(absolute_target), 'hooks')
+      @hooks_path ||= Dir.chdir(@target) { GitConfig.hooks_path }
     end
 
     def old_hooks_path

spec/overcommit/git_config_spec.rb

@@ -22,4 +22,59 @@
       end
     end
   end
+
+  describe '.hooks_path' do
+    subject { described_class.hooks_path }
+
+    context 'when not explicitly set' do
+      around do |example|
+        repo do
+          example.run
+        end
+      end
+
+      it 'returns the default hook path' do
+        expect(subject).to eq File.expand_path(File.join('.git', 'hooks'))
+      end
+    end
+
+    context 'when explicitly set to an empty string' do
+      around do |example|
+        repo do
+          `git config --local core.hooksPath ""`
+          example.run
+        end
+      end
+
+      it 'returns the default hook path' do
+        expect(subject).to eq File.expand_path(File.join('.git', 'hooks'))
+      end
+    end
+
+    context 'when explicitly set to an absolute path' do
+      around do |example|
+        repo do
+          `git config --local core.hooksPath /etc/hooks`
+          example.run
+        end
+      end
+
+      it 'returns the absolute path' do
+        expect(subject).to eq '/etc/hooks'
+      end
+    end
+
+    context 'when explicitly set to a relative path' do
+      around do |example|
+        repo do
+          `git config --local core.hooksPath my-hooks`
+          example.run
+        end
+      end
+
+      it 'returns the absolute path to the directory relative to the repo root' do
+        expect(subject).to eq File.expand_path('my-hooks')
+      end
+    end
+  end
 end

spec/overcommit/installer_spec.rb

@@ -142,6 +142,22 @@ def hook_files_installed?(hooks_dir)
             }.from(false).to(true)
           end
         end
+
+        context 'and a custom core.hooksPath directory is set' do
+          around do |example|
+            Dir.chdir(target) do
+              FileUtils.mkdir 'my-hooks'
+              `git config core.hooksPath my-hooks`
+              example.run
+            end
+          end
+
+          it 'installs the hooks in the custom directory' do
+            expect { subject }.to change { hook_files_installed?(File.join(target, 'my-hooks')) }.
+                               from(false).
+                               to(true)
+          end
+        end
       end
 
       context 'and an uninstall is requested' do