Hi, I am just starting out writing unit tests, and perhaps someone could
be kind enough to explain why I am seeing this behaviour:
First, my model looks like this:
Author <-HABTM-> Paper
With a model named ''authors_papers'' which belongs_to :author
and :paper.
This is to act as a lookup table which I believed Rails would do
automatically if set up like this.
This is my testing code, testing the Author model:
[code]
# Tests the Author<->Paper linkage through the automatic use of
# the author_papers model by Rails.
a = Author.new
p = Paper.new
assert_not_nil a
assert_not_nil p
assert a.save
assert p.save
# 1. Does the linkage work, returning an empty set?
assert_equal a.papers, []
# 2. Can we assign a paper to the author?
assert a.papers << p
assert a.save
assert_not_equal a.papers, []
# 3. Can we pull that paper out (read) again?
assert a.papers.include?(p)
# 4. Can we find the author from the paper?
assert_not_nil p.authors
assert p.authors.include?(a)
# 5. Can we update through the link?
assert p.authors.first.update_attributes(:lastname => "abc") #
Succeeds
assert_equal("abc", p.authors.first.lastname) #
Succeeds
puts "A.Lastname: #{a.lastname}" #
=>
<nil>
puts p.authors.first.lastname # =>
abc
assert_equal a, p.authors.first #
Succeeds
assert_equal("abc", a.lastname) #
Fails!
[/code]
The problem is in the last assertion - surely a.lastname should be set
to ''abc'' as we did that through the relationship from the
Paper? Any
help would be much appreciated, thanks.
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On 5 Oct 2007, a> # 5. Can we update through the link? > assert p.authors.first.update_attributes(:lastname => "abc") # > Succeeds > assert_equal("abc", p.authors.first.lastname) # > Succeeds > puts "A.Lastname: #{a.lastname}" # => > <nil> > puts p.authors.first.lastname # => > abc > assert_equal a, p.authors.first # > Succeeds > assert_equal("abc", a.lastname) # > Fails! > > [/code] > > The problem is in the last assertion - surely a.lastname should be set > to ''abc'' as we did that through the relationship from the Paper? Any > help would be much appreciated, thanks.The problem is that a contains stale data (it corresponds to the same row in the database as p.authors.first, but it''s a different ruby object(. If you did a.reload before the assertion, the test should pass. The compare on active record just compares the primary key, not the attributes, which is why assert_equal a, p.authors.first Fred --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
> The problem is that a contains stale dataAha - I had suspected it was something like this but my unfamiliarity with Rails prevented me from discovering the actual culprit. Thanks a lot for your time taken, it''s much appreciated, - N -- Posted via http://www.ruby-forum.com/. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
Peter Laurens wrote:> First, my model looks like this: > > Author <-HABTM-> Paper > > With a model named ''authors_papers'' which belongs_to :author and :paper. > This is to act as a lookup table which I believed Rails would do > automatically if set up like this.In addition to other comments... If by "Model" you mean a first-class object with more variables than just the two IDs, you shouldn''t use has_and_belongs_to_many. You should use: class Author... has_many :authors_papers has_many :papers, :through => :authors_papers This implies you should give authors_papers. However, if you said "Model" because you mean "table", and that table owns no data for itself, then use habtm!> This is my testing code, testing the Author model:This test case is too long. Short test cases are the key to happiness.> [code] > # Tests the Author<->Paper linkage through the automatic use of > # the author_papers model by Rails. > a = Author.new > p = Paper.newThose should be in the fixture system.> assert_not_nil a > assert_not_nil pDon''t assert something if another line will incidentally assert it. And we wouldn''t get very far in this test if either of those were nil. And give them complete names.> assert a.save > assert p.saveBy and large tests should save with save!. That satisfies the assertion concept by exploding if it can''t save. Further, save! will emit a diagnostic declaring why we could not save, and ''assert'' will only say "false is not true".> # 1. Does the linkage work, returning an empty set? > assert_equal a.papers, []Yes it''s harmless to add assertions that learn how Rails plumbing works!> # 2. Can we assign a paper to the author? > assert a.papers << p > assert a.save > assert_not_equal a.papers, []Would this work? assert_equal [p], a.papers I suspect you can force a reload on a collection by passing (:reload) to its successor. I have not confirmed this, so someone must speak up if I''m wrong! In general, prefer positive statements to negative ones, including positive "assert_equals" instead of negative "assert_not_equal". I also suspect one can pass (true), but that''s not self-documenting. Also, you should put the "reference" on the left side of an assertion, and the "sample" on the right. There are numerous trivial reasons to do this; just do it because there are _no_ good reasons to put the reference on the right!> # 5. Can we update through the link? > assert p.authors.first.update_attributes(:lastname => "abc") # > SucceedsThanks for the reminder that I should tack assert onto the beginning of all my test cases'' update_attributes calls! Now that you have experienced the joy of writing assertions for behavior that''s already written, you are going to have major fun writing tests for your own new code. More fun than endless debugging, at least! -- Phlip http://www.oreilly.com/catalog/9780596510657/ ^ assert_xpath --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
Phlip - thanks for you comments, will help me improve my testing a great deal. - N -- Posted via http://www.ruby-forum.com/. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---