Check option "primary_key" in check_foreign_key_without_index

This commit resolves #293.

lib/ridgepole/dsl_parser.rb

@@ -37,6 +37,7 @@ def check_foreign_key_without_index(table_name, attrs)
       attrs[:foreign_keys].each do |_, foreign_key_attrs|
         fk_index = foreign_key_attrs[:options][:column] || "#{foreign_key_attrs[:to_table].singularize}_id"
         next if attrs[:indices]&.any? { |_k, v| v[:column_name].first == fk_index }
+        next if attrs[:options][:primary_key] == fk_index
 
         Ridgepole::Logger.instance.warn(<<-MSG)
 [WARNING] Table `#{table_name}` has a foreign key on `#{fk_index}` column, but doesn't have any indexes on the column.

spec/mysql/fk/migrate_create_fk_spec.rb

@@ -192,9 +192,7 @@
       MSG
       subject.diff(dsl).migrate
 
-      expect do
-        subject.diff(dsl).migrate
-      end.to raise_error(/Mysql2::Error: Cannot drop index/)
+      expect(subject.diff(dsl).differ?).to be_truthy
     }
   end
 
@@ -219,7 +217,29 @@
       expect(Ridgepole::Logger.instance).to_not receive(:warn)
       subject.diff(dsl).migrate
 
-      expect { subject.diff(dsl).migrate }.to_not raise_error
+      expect(subject.diff(dsl).differ?).to be_falsey
+    }
+  end
+
+  context 'when create fk on the primary key' do
+    let(:dsl) do
+      erbh(<<-ERB)
+        create_table "users", force: :cascade, options: "ENGINE=InnoDB DEFAULT CHARSET=utf8" do |t|
+        end
+
+        create_table "icons", primary_key: "user_id", force: :cascade, options: "ENGINE=InnoDB DEFAULT CHARSET=utf8" do |t|
+        end
+        add_foreign_key "icons", "users", name: "fk_icons_users"
+      ERB
+    end
+
+    subject { client(dump_without_table_options: false) }
+
+    it {
+      expect(Ridgepole::Logger.instance).to_not receive(:warn)
+      subject.diff(dsl).migrate
+
+      expect(subject.diff(dsl).differ?).to be_falsey
     }
   end
 end