Include branch name(s) in "is invalid" alert

app/controllers/projects/compare_controller.rb

@@ -79,11 +79,11 @@ class Projects::CompareController < Projects::ApplicationController
   private
 
   def validate_refs!
-    valid = [head_ref, start_ref].map { |ref| valid_ref?(ref) }
+    invalid = [head_ref, start_ref].filter { |ref| !valid_ref?(ref) }
 
-    return if valid.all?
+    return if invalid.empty?
 
-    flash[:alert] = "Invalid branch name"
+    flash[:alert] = "Invalid branch name(s): #{invalid.join(', ')}"
     redirect_to project_compare_index_path(source_project)
   end
 

spec/controllers/projects/compare_controller_spec.rb

@@ -156,7 +156,7 @@ RSpec.describe Projects::CompareController do
       it 'shows a flash message and redirects' do
         show_request
 
-        expect(flash[:alert]).to eq('Invalid branch name')
+        expect(flash[:alert]).to eq("Invalid branch name(s): master%' AND 2554=4423 AND '%'='")
         expect(response).to have_gitlab_http_status(:found)
       end
     end
@@ -169,7 +169,20 @@ RSpec.describe Projects::CompareController do
       it 'shows a flash message and redirects' do
         show_request
 
-        expect(flash[:alert]).to eq('Invalid branch name')
+        expect(flash[:alert]).to eq("Invalid branch name(s): master%' AND 2554=4423 AND '%'='")
+        expect(response).to have_gitlab_http_status(:found)
+      end
+    end
+
+    context 'when the both refs are invalid' do
+      let(:from_project_id) { nil }
+      let(:from_ref) { "master%' AND 2554=4423 AND '%'='" }
+      let(:to_ref) { "improve%' =,awesome" }
+
+      it 'shows a flash message and redirects' do
+        show_request
+
+        expect(flash[:alert]).to eq("Invalid branch name(s): improve%' =,awesome, master%' AND 2554=4423 AND '%'='")
         expect(response).to have_gitlab_http_status(:found)
       end
     end