rspec - why does this attribute comparison usng assert_equal fail when they are the same, on ubuntu only?

Question

Two tests are failing - but only on Ubuntu(12) but not on my (new) Mac.

The failure two are Active Record object attribute comparisons but in all my effort to compare them, e.g. making hash's at the command line and pasting the attributes in, the comparison says they are the same.

A real puzzler as we have an extensive test suite with many hundreds of tests. Rails 3.2.8, rspec 2.11

Failure/Error: assert_equal @iep_service.attributes, IepService.first.attributes
 MiniTest::Assertion:
   <{"id"=>414,
    "duration"=>30,
    "frequency"=>3,
    "period"=>"week",
    "group_size"=>"group",
    "location"=>nil,
    "service"=>nil,
    "area_of_need"=>"speech",
    "created_at"=>Tue, 09 Oct 2012 01:53:39 UTC +00:00,
    "updated_at"=>Tue, 09 Oct 2012 01:53:39 UTC +00:00,
    "therapist_id"=>nil,
    "start_date"=>nil,
    "end_date"=>nil,
    "student_id"=>469,
    "adhoc"=>false}> expected but was
   <{"id"=>414,
    "duration"=>30,
    "frequency"=>3,
    "period"=>"week",
    "group_size"=>"group",
    "location"=>nil,
    "service"=>nil,
    "area_of_need"=>"speech",
    "created_at"=>Tue, 09 Oct 2012 01:53:39 UTC +00:00,
    "updated_at"=>Tue, 09 Oct 2012 01:53:39 UTC +00:00,
    "therapist_id"=>nil,
    "start_date"=>nil,
    "end_date"=>nil,
    "student_id"=>469,
    "adhoc"=>false}>.
# (eval):2:in `assert_equal'

Test Code:

  context "And a pre-existing Iep Service for one of those students" do
    before(:each) { @iep_service = FactoryGirl.create(:iep_service, :student => @district.students.first) }

    context "And an Iep Service CSV" do
      before(:each) { @spreadsheet = IepServiceSpreadsheet.new(@district, open_spec_fixture_file('sample-ieps.csv')) }

      specify "Prevent importing" do
        # Leave database untouched
        assert_equal 1, IepService.count
        assert_equal @iep_service.attributes, IepService.first.attributes

        # Provide error report
        assert @spreadsheet.error_report.any?
      end 
    end 
  end 

I also tried: @iep_service.attributes.should == IepService.first.attributes

but got:

 Failure/Error: @iep_service.attributes.should == IepService.first.attributes
   expected: {"id"=>421, "duration"=>30, "frequency"=>3, "period"=>"week", "group_size"=>"group", "location"=>nil, "service"=>nil, "area_of_need"=>"speech", "created_at"=>Tue, 09 Oct 2012 02:13:51 UTC +00:00, "updated_at"=>Tue, 09 Oct 2012 02:13:51 UTC +00:00, "therapist_id"=>nil, "start_date"=>nil, "end_date"=>nil, "student_id"=>483, "adhoc"=>false}
        got: {"id"=>421, "duration"=>30, "frequency"=>3, "period"=>"week", "group_size"=>"group", "location"=>nil, "service"=>nil, "area_of_need"=>"speech", "created_at"=>Tue, 09 Oct 2012 02:13:51 UTC +00:00, "updated_at"=>Tue, 09 Oct 2012 02:13:51 UTC +00:00, "therapist_id"=>nil, "start_date"=>nil, "end_date"=>nil, "student_id"=>483, "adhoc"=>false} (using ==)

with a big diff including "check the implementation of':

      Diff:{"id"=>421, "duration"=>30, "frequency"=>3, "period"=>"week",  
"group_size"=>"group", "location"=>nil, "service"=>nil, "area_of_need"=>"speech",  
"created_at"=>Tue, 09 Oct 2012 02:13:51 UTC +00:00, "updated_at"=>Tue, 09 Oct 2012 02:13:51 
UTC +00:00, "therapist_id"=>nil, "start_date"=>nil, "end_date"=>nil, "student_id"=>483, 
"adhoc"=>false}.==({"id"=>421, "duration"=>30, "frequency"=>3, "period"=>"week", 
"group_size"=>"group", "location"=>nil, "service"=>nil, "area_of_need"=>"speech", "created_at"=>Tue, 09 Oct 2012 02:13:51 UTC +00:00, "updated_at"=>Tue, 09 Oct 2012 02:13:51 UTC +00:00, "therapist_id"=>nil, "start_date"=>nil, "end_date"=>nil, "student_id"=>483, "adhoc"=>false}) returned false even though the diff between {"id"=>421, "duration"=>30, "frequency"=>3, "period"=>"week", "group_size"=>"group", "location"=>nil, "service"=>nil, 
"area_of_need"=>"speech", "created_at"=>Tue, 09 Oct 2012 02:13:51 UTC +00:00, 
"updated_at"=>Tue, 09 Oct 2012 02:13:51 UTC +00:00, "therapist_id"=>nil, "start_date"=>nil, 
"end_date"=>nil, "student_id"=>483, "adhoc"=>false} and {"id"=>421, "duration"=>30, 
"frequency"=>3, "period"=>"week", "group_size"=>"group", "location"=>nil, "service"=>nil, 
"area_of_need"=>"speech", "created_at"=>Tue, 09 Oct 2012 02:13:51 UTC +00:00, 
"updated_at"=>Tue, 09 Oct 2012 02:13:51 UTC +00:00, "therapist_id"=>nil, "start_date"=>nil, 
"end_date"=>nil, "student_id"=>483, "adhoc"=>false} is empty. 
Check the implementation of 
{"id"=>421, "duration"=>30, "frequency"=>3, "period"=>"week", "group_size"=>"group", 
"location"=>nil, "service"=>nil, "area_of_need"=>"speech", "created_at"=>Tue, 09 Oct 2012 
02:13:51 UTC +00:00, "updated_at"=>Tue, 09 Oct 2012 02:13:51 UTC +00:00, 
"therapist_id"=>nil, "start_date"=>nil, "end_date"=>nil, "student_id"=>483, 
"adhoc"=>false}.==.

Answer 1

No real answer has been given so I've gone with iterating through the atrributes, e.g.

i=0
while i < @student.attributes.count
  assert_equal @student.attributes[i], Student.first.attributes[i]
  i+= 1
end

# Comparing field by field as ruby hash comparison isn't working right - 
# but only on Ubuntu!