Fix another false assertions

* The assertions in AS::Duration don't actually assert.
 * The assertion in Railtie will pass even when `eager_load_namespaces`
   doesn't include `AppTemplate::Application` if `Rails.application` is
   truthy.

For more details, see here:

 * https://github.com/rails/rails/pull/16998
 * https://github.com/rails/rails/pull/17000

activesupport/test/core_ext/duration_test.rb

@@ -98,8 +98,8 @@ def test_fractional_days
 
   def test_since_and_ago
     t = Time.local(2000)
-    assert t + 1, 1.second.since(t)
-    assert t - 1, 1.second.ago(t)
+    assert_equal t + 1, 1.second.since(t)
+    assert_equal t - 1, 1.second.ago(t)
   end
 
   def test_since_and_ago_without_argument

railties/test/application/configuration_test.rb

@@ -182,7 +182,7 @@ def change
 
     test "application is always added to eager_load namespaces" do
       require "#{app_path}/config/application"
-      assert Rails.application, Rails.application.config.eager_load_namespaces
+      assert_includes Rails.application.config.eager_load_namespaces, AppTemplate::Application
     end
 
     test "the application can be eager loaded even when there are no frameworks" do