Support microsecond datetime precision on MariaDB 5.3+.

We support microsecond datetime precision for MySQL 5.6.4+. MariaDB has
supported it since 5.3.0, but even 10.x versions return a compatible
version string like `5.5.5-10.1.8-MariaDB-log` which we parse as 5.5.5,
before MySQL supported microsecond precision.

Specialize our version check to account for MariaDB to fix.

4 files changed, 47 insertions, 23 deletions

diff --git a/activerecord/test/cases/adapters/mysql2/datetime_precision_quoting_test.rb b/activerecord/test/cases/adapters/mysql2/datetime_precision_quoting_test.rb
new file mode 100644
index 0000000000..e349c67c93
--- /dev/null
+++ b/activerecord/test/cases/adapters/mysql2/datetime_precision_quoting_test.rb
@@ -0,0 +1,45 @@
+require "cases/helper"
+
+class Mysql2DatetimePrecisionQuotingTest < ActiveRecord::Mysql2TestCase
+  setup do
+    @connection = ActiveRecord::Base.connection
+  end
+
+  test 'microsecond precision for MySQL gte 5.6.4' do
+    stub_version '5.6.4'
+    assert_microsecond_precision
+  end
+
+  test 'no microsecond precision for MySQL lt 5.6.4' do
+    stub_version '5.6.3'
+    assert_no_microsecond_precision
+  end
+
+  test 'microsecond precision for MariaDB gte 5.3.0' do
+    stub_version '5.5.5-10.1.8-MariaDB-log'
+    assert_microsecond_precision
+  end
+
+  test 'no microsecond precision for MariaDB lt 5.3.0' do
+    stub_version '5.2.9-MariaDB'
+    assert_no_microsecond_precision
+  end
+
+  private
+    def assert_microsecond_precision
+      assert_match_quoted_microsecond_datetime(/\.000001\z/)
+    end
+
+    def assert_no_microsecond_precision
+      assert_match_quoted_microsecond_datetime(/\d\z/)
+    end
+
+    def assert_match_quoted_microsecond_datetime(match)
+      assert_match match, @connection.quoted_date(Time.now.change(usec: 1))
+    end
+
+    def stub_version(full_version_string)
+      @connection.stubs(:full_version).returns(full_version_string)
+      @connection.remove_instance_variable(:@version) if @connection.instance_variable_defined?(:@version)
+    end
+end
diff --git a/activerecord/test/cases/adapters/mysql2/quoting_test.rb b/activerecord/test/cases/adapters/mysql2/quoting_test.rb
deleted file mode 100644
index 2de7e1b526..0000000000
--- a/activerecord/test/cases/adapters/mysql2/quoting_test.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-require "cases/helper"
-
-class Mysql2QuotingTest < ActiveRecord::Mysql2TestCase
-  setup do
-    @connection = ActiveRecord::Base.connection
-  end
-
-  test 'quoted date precision for gte 5.6.4' do
-    @connection.stubs(:full_version).returns('5.6.4')
-    @connection.remove_instance_variable(:@version) if @connection.instance_variable_defined?(:@version)
-    t = Time.now.change(usec: 1)
-    assert_match(/\.000001\z/, @connection.quoted_date(t))
-  end
-
-  test 'quoted date precision for lt 5.6.4' do
-    @connection.stubs(:full_version).returns('5.6.3')
-    @connection.remove_instance_variable(:@version) if @connection.instance_variable_defined?(:@version)
-    t = Time.now.change(usec: 1)
-    assert_no_match(/\.000001\z/, @connection.quoted_date(t))
-  end
-end
diff --git a/activerecord/test/cases/date_time_precision_test.rb b/activerecord/test/cases/date_time_precision_test.rb
index e996d142a2..f8664d83bd 100644
--- a/activerecord/test/cases/date_time_precision_test.rb
+++ b/activerecord/test/cases/date_time_precision_test.rb
@@ -1,7 +1,7 @@
 require 'cases/helper'
 require 'support/schema_dumping_helper'
 
-if ActiveRecord::Base.connection.supports_datetime_with_precision?
+if subsecond_precision_supported?
 class DateTimePrecisionTest < ActiveRecord::TestCase
   include SchemaDumpingHelper
   self.use_transactional_tests = false
diff --git a/activerecord/test/cases/time_precision_test.rb b/activerecord/test/cases/time_precision_test.rb
index 3b6e4dcc2b..628a8eb771 100644
--- a/activerecord/test/cases/time_precision_test.rb
+++ b/activerecord/test/cases/time_precision_test.rb
@@ -1,7 +1,7 @@
 require 'cases/helper'
 require 'support/schema_dumping_helper'
 
-if ActiveRecord::Base.connection.supports_datetime_with_precision?
+if subsecond_precision_supported?
 class TimePrecisionTest < ActiveRecord::TestCase
   include SchemaDumpingHelper
   self.use_transactional_tests = false