Adds description to Snippet API updates

Allows description to be individually updated via the
Project and Personal Snippet REST API endpoint

changelogs/unreleased/vij-snippets-missing-param-requirement.yml

+---
+title: Add ability to update only Snippet descriptions via REST endpoint
+merge_request: 41581
+author:
+type: changed

lib/api/helpers/snippets_helpers.rb

@@ -41,6 +41,10 @@ module API
         mutually_exclusive :files, :file_name
       end
 
+      params :minimum_update_params do
+        at_least_one_of :content, :description, :files, :file_name, :title, :visibility
+      end
+
       def content_for(snippet)
         if snippet.empty_repo?
           env['api.format'] = :txt

lib/api/project_snippets.rb

@@ -93,8 +93,7 @@ module API
                               desc: 'The visibility of the snippet'
 
         use :update_file_params
-
-        at_least_one_of :title, :file_name, :content, :files, :visibility
+        use :minimum_update_params
       end
       # rubocop: disable CodeReuse/ActiveRecord
       put ":id/snippets/:snippet_id" do

lib/api/snippets.rb

@@ -106,8 +106,7 @@ module API
                               desc: 'The visibility of the snippet'
 
         use :update_file_params
-
-        at_least_one_of :title, :file_name, :content, :files, :visibility
+        use :minimum_update_params
       end
       put ':id' do
         snippet = snippets_for_current_user.find_by_id(params.delete(:id))

spec/requests/api/project_snippets_spec.rb

@@ -306,15 +306,9 @@ RSpec.describe API::ProjectSnippets do
 
     it_behaves_like 'snippet file updates'
     it_behaves_like 'snippet non-file updates'
+    it_behaves_like 'snippet individual non-file updates'
     it_behaves_like 'invalid snippet updates'
 
-    it 'updates snippet with visibility parameter' do
-      expect { update_snippet(params: { visibility: 'private' }) }
-        .to change { snippet.reload.visibility }
-
-      expect(snippet.visibility).to eq('private')
-    end
-
     it_behaves_like 'update with repository actions' do
       let(:snippet_without_repo) { create(:project_snippet, author: admin, project: project, visibility_level: visibility_level) }
     end

spec/requests/api/snippets_spec.rb

@@ -393,6 +393,7 @@ RSpec.describe API::Snippets do
 
     it_behaves_like 'snippet file updates'
     it_behaves_like 'snippet non-file updates'
+    it_behaves_like 'snippet individual non-file updates'
     it_behaves_like 'invalid snippet updates'
 
     it "returns 404 for another user's snippet" do

spec/support/shared_examples/requests/api/snippets_shared_examples.rb

@@ -170,6 +170,25 @@ RSpec.shared_examples 'snippet non-file updates' do
   end
 end
 
+RSpec.shared_examples 'snippet individual non-file updates' do
+  using RSpec::Parameterized::TableSyntax
+
+  where(:attribute, :updated_value) do
+    :description | 'new description'
+    :title       | 'new title'
+    :visibility  | 'private'
+  end
+
+  with_them do
+    it 'updates the attribute' do
+      params = { attribute => updated_value }
+
+      expect { update_snippet(params: params) }
+        .to change { snippet.reload.send(attribute) }.to(updated_value)
+    end
+  end
+end
+
 RSpec.shared_examples 'invalid snippet updates' do
   it 'returns 404 for invalid snippet id' do
     update_snippet(snippet_id: non_existing_record_id, params: { title: 'foo' })