CODEWITHSUNDEEP
ruby-on-railsrspec
Josiah Kiehl
Josiah Kiehl

Reputation: 3633

Expecting errors in rspec tests

I'm trying to expect an error in an rspec test.

lambda {Participant.create!({:user_id => three.id, :match_id => match.id, :team => 1})}.should raise_error StandardError

For now I'm just using StandardError to make sure it's working.

1) StandardError in 'Participant should never allow more participants than players'. 
   This game is already full.  Cannot add another player.
/home/josiah/Projects/Set-Match/app/models/participant.rb:12:in `do_not_exceed_player_count_in_match'
./spec/models/participant_spec.rb:24:

It clearly throws the error, but my test still fails.

Thoughts?

Upvotes: 32

Views: 19714

Answers (3)

Confusion
Confusion

Reputation: 16841

Since some time, but at least in RSpec 2.5, it is possible to use

expect {raise 'boom'}.to raise_error(RuntimeError, /boom/)

Upvotes: 49

crispy
crispy

Reputation: 5877

I had to fight with the same symptoms: 

def boom
  raise "boom"
end
boom.should raise_error

The test above fails because raise_error requires should to be called on a Proc (due to technical reasons, I suppose). Thus, wrapping a method call with a lambda works just fine:

  lambda { boom }.should raise_error

Unfortunately, the documentation does not say that explicitly and there is no RSpec Exception that reveals this behavior. There is a two year old ticket for that.

Upvotes: 7

Jonathan Julian
Jonathan Julian

Reputation: 12264

Your syntax looks correct. To debug this, simplify to make sure your spec is coded correctly.

it "should raise an error" do
  lambda {raise "boom"}.should raise_error
end

And then add more detail until it breaks.

lambda {raise "boom"}.should raise_error(RuntimeError)
lambda {raise StandardError.new("boom")}.should raise_error(StandardError)

Upvotes: 35

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