Fix a false positive for Rails/ReversibleMigration

Follow up to #110 (comment).

This PR fixes a false positive for `Rails/ReversibleMigration`
when using `t.remove` with `type` option in Rails 6.1.

Author: koic

changelog/fix_false_positive_for_rails_reversible_migration.md

@@ -0,0 +1 @@
+* [#553](https://github.com/rubocop/rubocop-rails/pull/553): Fix a false positive for `Rails/ReversibleMigration` when using `t.remove` with `type` option in Rails 6.1. ([@koic][])

lib/rubocop/cop/rails/reversible_migration.rb

@@ -317,16 +317,24 @@ def check_change_table_offense(receiver, node)
           return if receiver != node.receiver &&
                     reversible_change_table_call?(node)
 
+          action = if method_name == :remove
+                     target_rails_version >= 6.1 ? 't.remove (without type)' : 't.remove'
+                   else
+                     "change_table(with #{method_name})"
+                   end
+
           add_offense(
             node,
-            message: format(MSG, action: "change_table(with #{method_name})")
+            message: format(MSG, action: action)
           )
         end
 
         def reversible_change_table_call?(node)
           case node.method_name
-          when :change, :remove
+          when :change
             false
+          when :remove
+            target_rails_version >= 6.1 && all_hash_key?(node.arguments.last, :type)
           when :change_default, :change_column_default, :change_table_comment,
                :change_column_comment
             all_hash_key?(node.arguments.last, :from, :to)

spec/rubocop/cop/rails/reversible_migration_spec.rb

@@ -213,11 +213,35 @@ def change
       end
     RUBY
 
-    it_behaves_like 'offense', 'change_table(with remove)', <<~RUBY
-      change_table :users do |t|
-        t.remove :qualification
+    context 'remove' do
+      context 'Rails >= 6.1', :rails61 do
+        it_behaves_like 'accepts', 't.remove (with type)', <<~RUBY
+          change_table :users do |t|
+            t.remove(:posts, type: :text)
+          end
+        RUBY
+
+        it_behaves_like 'offense', 't.remove (without type)', <<~RUBY
+          change_table :users do |t|
+            t.remove(:posts)
+          end
+        RUBY
       end
-    RUBY
+
+      context 'Rails < 6.1', :rails60 do
+        it_behaves_like 'offense', 't.remove', <<~RUBY
+          change_table :users do |t|
+            t.remove(:posts, type: :text)
+          end
+        RUBY
+
+        it_behaves_like 'offense', 't.remove', <<~RUBY
+          change_table :users do |t|
+            t.remove(:posts)
+          end
+        RUBY
+      end
+    end
   end
 
   context 'remove_columns' do