Failing test: markdownify a number

test/test_filters.rb

@@ -40,6 +40,13 @@ class TestFilters < JekyllUnitTest
       )
     end
 
+    should "markdownify with a number" do
+      assert_equal(
+        "<p>404</p>\n",
+        @filter.markdownify(404)
+      )
+    end
+
     context "smartify filter" do
       should "convert quotes and typographic characters" do
         assert_equal(
@@ -81,6 +88,13 @@ class TestFilters < JekyllUnitTest
         assert_equal "5 &gt; 4", @filter.smartify("5 > 4")
         assert_equal "This &amp; that", @filter.smartify("This & that")
       end
+
+      should "convert a number to a string" do
+        assert_equal(
+          "404",
+          @filter.smartify(404)
+        )
+      end
     end
 
     should "sassify with simple string" do