Add JSON attribute test cases for SQLite3 adapter

activerecord/lib/active_record/connection_adapters/abstract_adapter.rb

@@ -478,6 +478,8 @@ def initialize_type_map(m = type_map)
           m.alias_type %r(number)i,    "decimal"
           m.alias_type %r(double)i,    "float"
 
+          m.register_type %r(^json)i, Type::Json.new
+
           m.register_type(%r(decimal)i) do |sql_type|
             scale = extract_scale(sql_type)
             precision = extract_precision(sql_type)

activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb

@@ -563,7 +563,6 @@ def initialize_type_map(m = type_map)
           m.register_type %r(longblob)i,   Type::Binary.new(limit: 2**32 - 1)
           m.register_type %r(^float)i,     Type::Float.new(limit: 24)
           m.register_type %r(^double)i,    Type::Float.new(limit: 53)
-          m.register_type %r(^json)i,      Type::Json.new
 
           register_integer_type m, %r(^bigint)i,    limit: 8
           register_integer_type m, %r(^int)i,       limit: 4

activerecord/test/cases/adapters/sqlite3/json_test.rb

+# frozen_string_literal: true
+
+require "cases/helper"
+require "cases/json_shared_test_cases"
+
+class SQLite3JSONTest < ActiveRecord::SQLite3TestCase
+  include JSONSharedTestCases
+
+  def setup
+    super
+    @connection.create_table("json_data_type") do |t|
+      t.column "payload", :json, default: {}
+      t.column "settings", :json
+    end
+  end
+
+  def test_default
+    @connection.add_column "json_data_type", "permissions", column_type, default: { "users": "read", "posts": ["read", "write"] }
+    klass.reset_column_information
+
+    assert_equal({ "users" => "read", "posts" => ["read", "write"] }, klass.column_defaults["permissions"])
+    assert_equal({ "users" => "read", "posts" => ["read", "write"] }, klass.new.permissions)
+  end
+
+  private
+    def column_type
+      :json
+    end
+end

activerecord/test/cases/json_shared_test_cases.rb

@@ -30,6 +30,7 @@ def test_column
   end
 
   def test_change_table_supports_json
+    skip unless @connection.supports_json?
     @connection.change_table("json_data_type") do |t|
       t.public_send column_type, "users"
     end
@@ -40,6 +41,7 @@ def test_change_table_supports_json
   end
 
   def test_schema_dumping
+    skip unless @connection.supports_json?
     output = dump_table_schema("json_data_type")
     assert_match(/t\.#{column_type}\s+"settings"/, output)
   end