Refactor `type_to_sql` to handle converting `limit` to `size` in itself

Also, improving an argument error message for `limit`, extracting around
`type_to_sql` code into schema statements, and more exercise tests.

2 files changed, 58 insertions, 10 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/mysql/schema_definitions.rb b/activerecord/lib/active_record/connection_adapters/mysql/schema_definitions.rb
index 8cb6b64fec..d21535a709 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql/schema_definitions.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql/schema_definitions.rb
@@ -64,16 +64,6 @@ module ActiveRecord
           case type
           when :virtual
             type = options[:type]
-          when :text, :blob, :binary
-            case (size = options[:size])&.to_s
-            when "tiny", "medium", "long"
-              sql_type = @conn.native_database_types[type][:name]
-              type = "#{size}#{sql_type}"
-            else
-              raise ArgumentError, <<~MSG unless size.nil?
-                #{size.inspect} is invalid :size value. Only :tiny, :medium, and :long are allowed.
-              MSG
-            end
           when :primary_key
             type = :integer
             options[:limit] ||= 8
diff --git a/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb
index e9484a08de..4018f0815c 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb
@@ -97,6 +97,30 @@ module ActiveRecord
           MySQL::SchemaDumper.create(self, options)
         end
 
+        # Maps logical Rails types to MySQL-specific data types.
+        def type_to_sql(type, limit: nil, precision: nil, scale: nil, size: limit_to_size(limit, type), unsigned: nil, **)
+          sql =
+            case type.to_s
+            when "integer"
+              integer_to_sql(limit)
+            when "text"
+              type_with_size_to_sql("text", size)
+            when "blob"
+              type_with_size_to_sql("blob", size)
+            when "binary"
+              if (0..0xfff) === limit
+                "varbinary(#{limit})"
+              else
+                type_with_size_to_sql("blob", size)
+              end
+            else
+              super
+            end
+
+          sql = "#{sql} unsigned" if unsigned && type != :primary_key
+          sql
+        end
+
         private
           CHARSETS_OF_4BYTES_MAXLEN = ["utf8mb4", "utf16", "utf16le", "utf32"]
 
@@ -197,6 +221,40 @@ module ActiveRecord
             schema, name = nil, schema unless name
             [schema, name]
           end
+
+          def type_with_size_to_sql(type, size)
+            case size&.to_s
+            when nil, "tiny", "medium", "long"
+              "#{size}#{type}"
+            else
+              raise ArgumentError,
+                "#{size.inspect} is invalid :size value. Only :tiny, :medium, and :long are allowed."
+            end
+          end
+
+          def limit_to_size(limit, type)
+            case type.to_s
+            when "text", "blob", "binary"
+              case limit
+              when 0..0xff;               "tiny"
+              when nil, 0x100..0xffff;    nil
+              when 0x10000..0xffffff;     "medium"
+              when 0x1000000..0xffffffff; "long"
+              else raise ActiveRecordError, "No #{type} type has byte size #{limit}"
+              end
+            end
+          end
+
+          def integer_to_sql(limit)
+            case limit
+            when 1; "tinyint"
+            when 2; "smallint"
+            when 3; "mediumint"
+            when nil, 4; "int"
+            when 5..8; "bigint"
+            else raise ActiveRecordError, "No integer type has byte size #{limit}. Use a decimal with scale 0 instead."
+            end
+          end
       end
     end
   end