Spec: Improve jenkins page formatters

This will allow the test result pages in jenkins to *always*
show timestamps so it's clear what we mean by "oldest"
and "newest."

Change-Id: If7a317250eab118e961a0bc29103c86e134ce09c
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/240189
QA-Review: James Butters <jbutters@instructure.com>
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Reviewed-by: Aaron Ogata <aogata@instructure.com>
Reviewed-by: James Butters <jbutters@instructure.com>
Product-Review: Derek Bender <djbender@instructure.com>

spec/formatters/error_context/base_formatter.rb

@@ -100,9 +100,10 @@ module ErrorContext
 
       def note_recent_spec_run(example)
         recent_spec_runs << {
-          location: RerunArgument.for(example),
           exception: example.exception,
-          pending: example.pending
+          location: RerunArgument.for(example),
+          pending: example.pending,
+          recorded_at: Time.zone.now
         }
         self.num_failures += 1 if example.exception
       end

spec/formatters/error_context/html_page_formatter.rb

@@ -60,13 +60,14 @@ module ErrorContext
       base_path = "../" + ("../" * summary.spec_path.count("/"))
       errors = ErrorSummary.recent_spec_runs.reverse.map do |run|
         location = ERB::Util.html_escape(run[:location])
-        if run[:pending]
+        contents = if run[:pending]
           "bin/rspec #{location} (pending)"
         elsif run[:exception]
           "bin/rspec <a href=\"#{base_path + location}/index.html\">#{location}</a> (failed)"
         else
           "bin/rspec #{location}"
         end
+        "#{run[:recorded_at]}: #{contents}"
       end.join("<br>")
 
       "(newest)<br>#{errors}<br>(oldest)".html_safe