Quote these dates to prevent intermittent test failure. Suppose local time is...

Quote these dates to prevent intermittent test failure. Suppose local time is 00:50 GMT+1. Without the quoting, the YAML parser would parse this as 00:50 UTC, into the local time of 01:50 GMT+1. Then, it would get written into the database in local time as 01:50. When it came back out the UTC date from the database and the UTC date of two weeks ago would be compared. The former would be 23:50, and the latter would be 00:50, so the two dates would differ, causing the assertion to fail. Quoting it prevents the YAML parser from getting involved.

activerecord/test/cases/fixtures_test.rb

@@ -587,8 +587,8 @@ def test_only_populates_columns_that_exist
   end
 
   def test_preserves_existing_fixture_data
-    assert_equal(2.weeks.ago.utc.to_date, pirates(:redbeard).created_on.utc.to_date)
-    assert_equal(2.weeks.ago.utc.to_date, pirates(:redbeard).updated_on.utc.to_date)
+    assert_equal(2.weeks.ago.to_date, pirates(:redbeard).created_on.to_date)
+    assert_equal(2.weeks.ago.to_date, pirates(:redbeard).updated_on.to_date)
   end
 
   def test_generates_unique_ids

activerecord/test/fixtures/pirates.yml

@@ -5,5 +5,5 @@ blackbeard:
 redbeard:
   catchphrase: "Avast!"
   parrot: louis
-  created_on: <%= 2.weeks.ago.to_s(:db) %>
-  updated_on: <%= 2.weeks.ago.to_s(:db) %>
+  created_on: "<%= 2.weeks.ago.to_s(:db) %>"
+  updated_on: "<%= 2.weeks.ago.to_s(:db) %>"