How to spec the existence of specs

Testing RSpec
1

I’m writing a Rails plugin that generates specs for Rails models.
Obviously, I want to use RSpec to spec this plugin.

The plugin, called ModelSpeccer, contains a module with three methods.
Each method generates specs depending on its arguments. How can my
plugin’s specs check that each method in ModelSpeccer created the
correct specs?

Thanks,
Nick

2

Each method generates specs depending on its arguments

How does each method generate the specs?

  • Using script/generate rspec…
    or
  • File handling and writing your own?

–
Joseph W.
http://www.joesniff.co.uk

Nick H. wrote:

I’m writing a Rails plugin that generates specs for Rails models.
Obviously, I want to use RSpec to spec this plugin.

The plugin, called ModelSpeccer, contains a module with three methods.
Each method generates specs depending on its arguments. How can my
plugin’s specs check that each method in ModelSpeccer created the
correct specs?

Thanks,
Nick

3

On 2008-08-29, at 05:06, Joseph W. wrote:

Each method generates specs depending on its arguments

How does each method generate the specs?

  • Using script/generate rspec…
    or
  • File handling and writing your own?

–
Joseph W.
http://www.joesniff.co.uk

Hi again Joseph. Each method generates the specs by calling RSpec’s
#describe and #it methods, like this:

def check_model_attributes_when_nil(model, …
…
columns_to_check.each do |attribute|
describe model, “with ‘#{attribute}’ set to nil” do
…
it “should be invalid” do
@model_instance.should_not be_valid
end
…
end
end

4

On 2008-08-31, at 15:40, Joseph W. wrote:

invalid_values)
example_group.run.should be_true
and then you can check if they succeed/fail. An alternative to
checking
the output could be to test that the model has the relevant methods
invoked on it.

I hope that helps

Joseph W.
http://www.joesniff.co.uk

Hi Joseph. I just realised that I hadn’t responded to this email of
yours. Thanks for thinking about it and showing me how you’d take a
stab at it. I’m going to give it another shot in the next few days.
When I do, I’ll post my results.

Cheers,
Nick

5

I’ve been giving this some thought, I’ve not had the chance to test it
out yet,
but here are my examples:

it “should add a ‘it’ test” do
example_group = Class.new(Spec::Example::ExampleGroup)
example_group.should_receive(:it).with(…) …

example.class_eval do
describe_model_attribute(model, attribute, valid_values,
invalid_values)
end

end

describe “valid model”
it “should generate a spec which will pass” do
example_group = Class.new(Spec::Example::ExampleGroup) do
describe_model_attribute(model, attribute, valid_values,
invalid_values)
end
example_group.run.should be_true
end
end

So this means the scope of ‘it’ and ‘describe’ are against ExampleGroup.
Giving you something to mock against to check ‘it’/‘describe’.

Invoking run on the ExampleGroup class will run the specs you generate,
and then you can check if they succeed/fail. An alternative to checking
the output could be to test that the model has the relevant methods
invoked on it.

I hope that helps

Joseph W.
http://www.joesniff.co.uk

Nick H. wrote:

On 2008-08-29, at 05:06, Joseph W. wrote:

Each method generates specs depending on its arguments

How does each method generate the specs?

  • Using script/generate rspec…
    or
  • File handling and writing your own?

–
Joseph W.
http://www.joesniff.co.uk

Hi again Joseph. Each method generates the specs by calling RSpec’s
#describe and #it methods, like this:

def check_model_attributes_when_nil(model, …
…
columns_to_check.each do |attribute|
describe model, “with ‘#{attribute}’ set to nil” do
…
it “should be invalid” do
@model_instance.should_not be_valid
end
…
end
end