Use connection.error_number in MySQLDatabaseTasks

MySQLDatabaseTasks, like AbstractMysqlAdapter, should be able to operate
on any mysql adapter, not just mysql2. Errors having a .error_number
attribute is a mysql2 specific API, which we (Rails) don't control, so
we should instead use connection.error_number(err), which we do.

This also updates tests to better test how this really works, previously
it stubbed create_database to raise Tasks::DatabaseAlreadyExists, which
can never happen.

2 files changed, 9 insertions, 4 deletions

diff --git a/activerecord/lib/active_record/tasks/mysql_database_tasks.rb b/activerecord/lib/active_record/tasks/mysql_database_tasks.rb
index a7e04007a9..e3efeb75b5 100644
--- a/activerecord/lib/active_record/tasks/mysql_database_tasks.rb
+++ b/activerecord/lib/active_record/tasks/mysql_database_tasks.rb
@@ -16,7 +16,7 @@ module ActiveRecord
         connection.create_database configuration["database"], creation_options
         establish_connection configuration
       rescue ActiveRecord::StatementInvalid => error
-        if error.cause.error_number == ER_DB_CREATE_EXISTS
+        if connection.error_number(error.cause) == ER_DB_CREATE_EXISTS
           raise DatabaseAlreadyExists
         else
           raise
diff --git a/activerecord/test/cases/tasks/mysql_rake_test.rb b/activerecord/test/cases/tasks/mysql_rake_test.rb
index 258132835f..ac3c5bc26e 100644
--- a/activerecord/test/cases/tasks/mysql_rake_test.rb
+++ b/activerecord/test/cases/tasks/mysql_rake_test.rb
@@ -7,7 +7,10 @@ if current_adapter?(:Mysql2Adapter)
   module ActiveRecord
     class MysqlDBCreateTest < ActiveRecord::TestCase
       def setup
-        @connection    = Class.new { def create_database(*); end }.new
+        @connection = Class.new do
+          def create_database(*); end
+          def error_number(_); end
+        end.new
         @configuration = {
           "adapter"  => "mysql2",
           "database" => "my-app-db"
@@ -90,9 +93,11 @@ if current_adapter?(:Mysql2Adapter)
         with_stubbed_connection_establish_connection do
           ActiveRecord::Base.connection.stub(
             :create_database,
-            proc { raise ActiveRecord::Tasks::DatabaseAlreadyExists }
+            proc { raise ActiveRecord::StatementInvalid }
           ) do
-            ActiveRecord::Tasks::DatabaseTasks.create @configuration
+            ActiveRecord::Base.connection.stub(:error_number, 1007) do
+              ActiveRecord::Tasks::DatabaseTasks.create @configuration
+            end
 
             assert_equal "Database 'my-app-db' already exists\n", $stderr.string
           end