cereal.diff

diff -r old/lib/minitest.rb new/lib/minitest.rb
--- old/lib/minitest.rb
+++ new/lib/minitest.rb
@@ -647,7 +647,7 @@
     ##
     # The location of the test method.
 
-    attr_accessor :source_location
+    attr_writer :source_location
 
     ##
     # Create a new test result from a Runnable instance.
@@ -658,15 +658,22 @@
       r = self.new o.name
       r.klass      = o.class.name
       r.assertions = o.assertions
-      r.failures   = o.failures.dup
+      r.failures   = o.failures
       r.time       = o.time
       r.metadata   = o.metadata if o.metadata?
 
-      r.source_location = o.method(o.name).source_location rescue ["unknown", -1]
+      r.source_location = o.method(o.name).source_location unless runnable.passed?
 
       r
     end
 
+    ##
+    # The location of the test method.
+
+    def source_location
+      @source_location ||= ["unknown", -1]
+    end
+
     def class_name # :nodoc:
       self.klass # for Minitest::Reportable
     end
diff -r old/test/minitest/test_minitest_test.rb new/test/minitest/test_minitest_test.rb
--- old/test/minitest/test_minitest_test.rb
+++ new/test/minitest/test_minitest_test.rb
@@ -782,6 +782,10 @@
     tc.assertions = 42
     tc.failures << "a failure"
 
+    def tc.passed?
+      false
+    end
+
     yield tc if block_given?
 
     def tc.setup