Add assertions to adjust timestamps on MySQL.

Tests were failing on MySQL due to timestamps with differing usec flunking
`assert_equal`.

Happened because Rails 4.2 added support for fractional seconds precision. Travis, however,
doesn't support the required MySQL 5.6 for it.

Bend the timestamps to strip out fractional seconds when tests are run with MySQL.

test/test_helper.rb

@@ -43,6 +43,36 @@ class ActiveSupport::TestCase
     DatabaseCleaner.clean if using_mysql?
     Thread.current[:paper_trail] = nil
   end
+
+  private
+
+  def assert_attributes_equal(expected, actual)
+    if using_mysql?
+      expected, actual = expected.dup, actual.dup
+
+      # Adjust timestamps for missing fractional seconds precision.
+      %w(created_at updated_at).each do |timestamp|
+        expected[timestamp] = expected[timestamp].change(usec: 0)
+        actual[timestamp]   = actual[timestamp].change(usec: 0)
+      end
+    end
+
+    assert_equal expected, actual
+  end
+
+  def assert_changes_equal(expected, actual)
+    if using_mysql?
+      expected, actual = expected.dup, actual.dup
+
+      # Adjust timestamps for missing fractional seconds precision.
+      %w(created_at updated_at).each do |timestamp|
+        expected[timestamp][1] = expected[timestamp][1].change(usec: 0)
+        actual[timestamp][1]   = actual[timestamp][1].change(usec: 0)
+      end
+    end
+
+    assert_equal expected, actual
+  end
 end
 
 #

test/unit/model_test.rb

@@ -229,7 +229,7 @@ class HasPaperTrailModelTest < ActiveSupport::TestCase
         }
 
         assert_kind_of Time, @widget.versions.last.changeset['updated_at'][1]
-        assert_equal changes, @widget.versions.last.changeset
+        assert_changes_equal changes, @widget.versions.last.changeset
       end
 
       context 'and then updated without any changes' do
@@ -375,7 +375,7 @@ class HasPaperTrailModelTest < ActiveSupport::TestCase
 
           should 'be available in its previous version' do
             assert_equal @widget.id, @reified_widget.id
-            assert_equal @widget.attributes, @reified_widget.attributes
+            assert_attributes_equal @widget.attributes, @reified_widget.attributes
           end
 
           should 'be re-creatable from its previous version' do

test/unit/protected_attrs_test.rb

@@ -38,7 +38,7 @@ class ProtectedAttrsTest < ActiveSupport::TestCase
         # For some reason this test seems to be broken in JRuby 1.9 mode in the
         # test env even though it works in the console. WTF?
         unless ActiveRecord::VERSION::MAJOR >= 4 && defined?(JRUBY_VERSION)
-          assert_equal @widget.previous_version.attributes, @initial_attributes
+          assert_attributes_equal @widget.previous_version.attributes, @initial_attributes
         end
       end
     end