Implement the `tag` commands

app/services/quick_actions/interpret_service.rb

@@ -583,6 +583,23 @@ module QuickActions
       @updates[:confidential] = true
     end
 
+    desc 'Tag this commit.'
+    explanation do |(tag_name), _|
+      "Tags this commit to #{tag_name}."
+    end
+    params 'v1.2.3 <message>'
+    parse_params do |tag_name_and_message|
+      tag_name_and_message.split(' ', 2)
+    end
+    condition do
+      issuable.is_a?(Commit)
+      # TODO authorize
+    end
+    command :tag do |(tag_name, message)|
+      @updates[:tag_name] = tag_name
+      @updates[:tag_message] = message
+    end
+
     def extract_users(params)
       return [] if params.nil?
 

spec/services/quick_actions/interpret_service_spec.rb

@@ -7,6 +7,7 @@ describe QuickActions::InterpretService do
   let(:developer2) { create(:user) }
   let(:issue) { create(:issue, project: project) }
   let(:milestone) { create(:milestone, project: project, title: '9.10') }
+  let(:commit) { create(:commit, project: project) }
   let(:inprogress) { create(:label, project: project, title: 'In Progress') }
   let(:bug) { create(:label, project: project, title: 'Bug') }
   let(:note) { build(:note, commit_id: merge_request.diff_head_sha) }
@@ -367,6 +368,14 @@ describe QuickActions::InterpretService do
       end
     end
 
+    shared_examples 'tag command' do
+      it 'tags a commit' do
+        _, updates = service.execute(content, issuable)
+
+        expect(updates).to eq(tag_name: tag_name, tag_message: tag_message)
+      end
+    end
+
     it_behaves_like 'reopen command' do
       let(:content) { '/reopen' }
       let(:issuable) { issue }
@@ -1179,6 +1188,32 @@ describe QuickActions::InterpretService do
         it_behaves_like 'empty command'
       end
     end
+
+    context '/tag command' do
+      let(:issuable) { commit }
+
+      context 'ignores command with no argument' do
+        it_behaves_like 'empty command' do
+          let(:content) { '/tag' }
+        end
+      end
+
+      context 'tags a commit with a tag name' do
+        it_behaves_like 'tag command' do
+          let(:tag_name) { 'v1.2.3' }
+          let(:tag_message) { nil }
+          let(:content) { "/tag #{tag_name}" }
+        end
+      end
+
+      context 'tags a commit with a tag name and message' do
+        it_behaves_like 'tag command' do
+          let(:tag_name) { 'v1.2.3' }
+          let(:tag_message) { 'Stable release' }
+          let(:content) { "/tag #{tag_name} #{tag_message}" }
+        end
+      end
+    end
   end
 
   describe '#explain' do
@@ -1397,6 +1432,16 @@ describe QuickActions::InterpretService do
       end
     end
 
+    describe 'tag a commit' do
+      let(:content) { '/tag 1.2.3 some message' }
+
+      it 'includes the tag name' do
+        _, explanations = service.explain(content, commit)
+
+        expect(explanations).to eq(["Tags this commit to 1.2.3."])
+      end
+    end
+
     # EE-specific tests
 
     describe 'weight command' do