Fix to correctly schema dump the tinyblob

Currently `tinyblob` is dumped to `t.binary "tiny_blob", limit: 255`.
But `t.binary ... limit: 255` is generating SQL to `varchar(255)`.
It is incorrect. This commit fixes this problem.

activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb

@@ -134,6 +134,7 @@ module ActiveRecord
         time:        { name: "time" },
         date:        { name: "date" },
         binary:      { name: "blob" },
+        blob:        { name: "blob" },
         boolean:     { name: "tinyint", limit: 1 },
         bigint:      { name: "bigint" },
         json:        { name: "json" },
@@ -679,12 +680,18 @@ module ActiveRecord
       # Maps logical Rails types to MySQL-specific data types.
       def type_to_sql(type, limit = nil, precision = nil, scale = nil, unsigned = nil)
         sql = case type.to_s
-        when 'binary'
-          binary_to_sql(limit)
         when 'integer'
           integer_to_sql(limit)
         when 'text'
           text_to_sql(limit)
+        when 'blob'
+          binary_to_sql(limit)
+        when 'binary'
+          if (0..0xfff) === limit
+            "varbinary(#{limit})"
+          else
+            binary_to_sql(limit)
+          end
         else
           super(type, limit, precision, scale)
         end
@@ -997,15 +1004,6 @@ module ActiveRecord
         MySQL::TableDefinition.new(native_database_types, name, temporary, options, as)
       end
 
-      def binary_to_sql(limit) # :nodoc:
-        case limit
-        when 0..0xfff;           "varbinary(#{limit})"
-        when nil;                "blob"
-        when 0x1000..0xffffffff; "blob(#{limit})"
-        else raise(ActiveRecordError, "No binary type has byte length #{limit}")
-        end
-      end
-
       def integer_to_sql(limit) # :nodoc:
         case limit
         when 1; 'tinyint'
@@ -1028,6 +1026,16 @@ module ActiveRecord
         end
       end
 
+      def binary_to_sql(limit) # :nodoc:
+        case limit
+        when 0..0xff;               'tinyblob'
+        when nil, 0x100..0xffff;    'blob'
+        when 0x10000..0xffffff;     'mediumblob'
+        when 0x1000000..0xffffffff; 'longblob'
+        else raise(ActiveRecordError, "No binary type has byte length #{limit}")
+        end
+      end
+
       class MysqlJson < Type::Internal::AbstractJson # :nodoc:
         def changed_in_place?(raw_old_value, new_value)
           # Normalization is required because MySQL JSON data format includes

activerecord/lib/active_record/connection_adapters/mysql/schema_definitions.rb

@@ -7,6 +7,10 @@ module ActiveRecord
           super
         end
 
+        def blob(*args, **options)
+          args.each { |name| column(name, :blob, options) }
+        end
+
         def json(*args, **options)
           args.each { |name| column(name, :json, options) }
         end

activerecord/lib/active_record/connection_adapters/mysql/schema_dumper.rb

@@ -27,6 +27,14 @@ module ActiveRecord
 
         private
 
+        def schema_type(column)
+          if column.sql_type == 'tinyblob'
+            'blob'
+          else
+            super
+          end
+        end
+
         def schema_limit(column)
           super unless column.type == :boolean
         end

activerecord/test/cases/adapters/mysql/sql_types_test.rb

@@ -4,7 +4,7 @@ class MysqlSqlTypesTest < ActiveRecord::MysqlTestCase
   def test_binary_types
     assert_equal 'varbinary(64)', type_to_sql(:binary, 64)
     assert_equal 'varbinary(4095)', type_to_sql(:binary, 4095)
-    assert_equal 'blob(4096)', type_to_sql(:binary, 4096)
+    assert_equal 'blob', type_to_sql(:binary, 4096)
     assert_equal 'blob', type_to_sql(:binary)
   end
 

activerecord/test/cases/adapters/mysql2/sql_types_test.rb

@@ -4,7 +4,7 @@ class Mysql2SqlTypesTest < ActiveRecord::Mysql2TestCase
   def test_binary_types
     assert_equal 'varbinary(64)', type_to_sql(:binary, 64)
     assert_equal 'varbinary(4095)', type_to_sql(:binary, 4095)
-    assert_equal 'blob(4096)', type_to_sql(:binary, 4096)
+    assert_equal 'blob', type_to_sql(:binary, 4096)
     assert_equal 'blob', type_to_sql(:binary)
   end
 

activerecord/test/cases/schema_dumper_test.rb

@@ -215,7 +215,7 @@ class SchemaDumperTest < ActiveRecord::TestCase
 
     def test_schema_dump_includes_length_for_mysql_blob_and_text_fields
       output = standard_dump
-      assert_match %r{t\.binary\s+"tiny_blob",\s+limit: 255$}, output
+      assert_match %r{t\.blob\s+"tiny_blob",\s+limit: 255$}, output
       assert_match %r{t\.binary\s+"normal_blob",\s+limit: 65535$}, output
       assert_match %r{t\.binary\s+"medium_blob",\s+limit: 16777215$}, output
       assert_match %r{t\.binary\s+"long_blob",\s+limit: 4294967295$}, output

activerecord/test/schema/mysql2_specific_schema.rb

@@ -2,7 +2,7 @@ ActiveRecord::Schema.define do
   create_table :binary_fields, force: true do |t|
     t.binary :var_binary, limit: 255
     t.binary :var_binary_large, limit: 4095
-    t.column :tiny_blob, 'tinyblob', limit: 255
+    t.blob   :tiny_blob, limit: 255
     t.binary :normal_blob, limit: 65535
     t.binary :medium_blob, limit: 16777215
     t.binary :long_blob, limit: 2147483647

activerecord/test/schema/mysql_specific_schema.rb

@@ -2,7 +2,7 @@ ActiveRecord::Schema.define do
   create_table :binary_fields, force: true do |t|
     t.binary :var_binary, limit: 255
     t.binary :var_binary_large, limit: 4095
-    t.column :tiny_blob, 'tinyblob', limit: 255
+    t.blob   :tiny_blob, limit: 255
     t.binary :normal_blob, limit: 65535
     t.binary :medium_blob, limit: 16777215
     t.binary :long_blob, limit: 2147483647