Merge pull request #14363 from arthurnn/usec_tests_mysql56

Add more tests for mysql 5.6 microseconds + Fix tests

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

@@ -97,6 +97,13 @@ def test_logs_name_rename_column_sql
     @connection.execute "DROP TABLE `bar_baz`"
   end
 
+  if mysql_56?
+    def test_quote_time_usec
+      assert_equal "'1970-01-01 00:00:00.000000'", @connection.quote(Time.at(0))
+      assert_equal "'1970-01-01 00:00:00.000000'", @connection.quote(Time.at(0).to_datetime)
+    end
+  end
+
   private
 
   def run_without_connection

activerecord/test/cases/persistence_test.rb

@@ -452,7 +452,7 @@ def test_update_attribute_with_one_updated
 
   def test_update_attribute_for_updated_at_on
     developer = Developer.find(1)
-    prev_month = Time.now.prev_month
+    prev_month = Time.now.prev_month.change(usec: 0)
 
     developer.update_attribute(:updated_at, prev_month)
     assert_equal prev_month, developer.updated_at
@@ -523,7 +523,7 @@ def test_update_column_for_readonly_attribute
 
   def test_update_column_should_not_modify_updated_at
     developer = Developer.find(1)
-    prev_month = Time.now.prev_month
+    prev_month = Time.now.prev_month.change(usec: 0)
 
     developer.update_column(:updated_at, prev_month)
     assert_equal prev_month, developer.updated_at
@@ -620,7 +620,7 @@ def test_update_columns_with_one_readonly_attribute
 
   def test_update_columns_should_not_modify_updated_at
     developer = Developer.find(1)
-    prev_month = Time.now.prev_month
+    prev_month = Time.now.prev_month.change(usec: 0)
 
     developer.update_columns(updated_at: prev_month)
     assert_equal prev_month, developer.updated_at