Add SubmoduleStatus post-commit hook

Author: jawshooah

config/default.yml

@@ -456,6 +456,12 @@ PostCommit:
     description: 'Generating tags file from source'
     required_executable: 'ctags'
 
+  SubmoduleStatus:
+    enabled: false
+    description: 'Checking submodule status'
+    required_executable: 'git'
+    flags: ['submodule', 'status']
+
 # Hooks that run after `git merge` executes successfully (no merge conflicts).
 PostMerge:
   ALL:

lib/overcommit/hook/post_commit/submodule_status.rb

@@ -0,0 +1,55 @@
+module Overcommit::Hook::PostCommit
+  # Checks the status of submodules in the current repository and
+  # notifies the user if any are uninitialized, out of date with
+  # the current index, or contain merge conflicts.
+  class SubmoduleStatus < Base
+    SUBMODULE_STATUS_REGEX = /
+      ^\s*(?<prefix>[-+U]?)(?<sha1>\w+)
+      \s(?<path>[^\s]+?)
+      (?:\s\((?<describe>.+)\))?$
+    /x
+
+    SubmoduleStatus = Struct.new(:prefix, :sha1, :path, :describe) do
+      def uninitialized?
+        prefix == '-'
+      end
+
+      def outdated?
+        prefix == '+'
+      end
+
+      def merge_conflict?
+        prefix == 'U'
+      end
+    end
+
+    def run
+      result = execute(command)
+      submodule_statuses = parse_submodule_statuses(result.stdout)
+
+      messages = []
+      submodule_statuses.each do |submodule_status|
+        path = submodule_status.path
+        if submodule_status.uninitialized?
+          messages << "Submodule #{path} is uninitialized."
+        elsif submodule_status.outdated?
+          messages << "Submodule #{path} is out of date with the current index."
+        elsif submodule_status.merge_conflict?
+          messages << "Submodule #{path} has merge conflicts."
+        end
+      end
+
+      return :pass if messages.empty?
+
+      [:warn, messages.join("\n")]
+    end
+
+    private
+
+    def parse_submodule_statuses(output)
+      output.scan(SUBMODULE_STATUS_REGEX).map do |prefix, sha1, path, describe|
+        SubmoduleStatus.new(prefix, sha1, path, describe)
+      end
+    end
+  end
+end