How to test that a specific error message is thrown


#1

Hi,

If I have this line in my model:
validates_presence_of :name, :message => “Please enter a name”

and I test this with the following code:

def test_should_require_name
user= User.new(valid_user_attributes(:name => “”))
assert !applicant.save
end

Is there a way to write an additional test to ensure that not only the
name field may not be blank, but that if it is blank the message “Please
neter a name” is thrown?

Many thanks


#2

Yep

try…

def test_should_not_be_valid_without_name
user = User.new
user.valid?
assert_equal user.errors.on(:name), “Please enter a name”
end


#3

Hi,

That worked perfectly.
Thank you very much.


#4

Here’s an article about BDD if you’re interested:
http://dannorth.net/introducing-bdd

Hey, cool article. Thanks a lot.
I will read that through this evening.
I’m still a bit new to TDD and am still finding my way around, so thanks
for the advice.


#5

You’re welcome.

Just a little advice -

It’s generally better practice to be more specific with the names of
your tests. I find it helps define exactly what it is you’re testing
for.

Here’s an article about BDD if you’re interested:
http://dannorth.net/introducing-bdd


#6

Hope you find that useful
:slight_smile:

Thanks for the tip.
I’m currently reading a book “Professional Webdevelopment with RoR2” by
Jens-Christian F. and he’s just getting into Rspec.
I wasn’t sure how indepth I should read that part, but now I will
definitely take the time to check it out.


#7

I’d also recommend checking out rspec.

It’s a BDD framework that helps you write tests that feel a lot more
intuitive than the default rails testing suite.

simply install the rspec gem and the rspec-rails gem

Specs are written like:

describe User do

it “should not be valid without a name” do
user = User.new
user.valid?
user.errors.on(:name).should == “can’t be blank”
end

end

Hope you find that useful
:slight_smile: