How to use Test::Unit::Assertions from class methods?

ruby-talk
1

For unit tests I've written a mock object that should check its
arguments against expected arguments using assertions from
Test::Unit::Assertions. For instance methods I can include
Test::Unit::Assertions in the mock class, that's easy. But how can I
use these assertions in a class method?

Michael

···

--
Michael Schuerig Those who call the shots
mailto:michael@schuerig.de Are never in the line of fire
http://www.schuerig.de/michael/ --Ani DiFranco, Not So Soft

2

Michael Schuerig ha scritto:

For unit tests I've written a mock object that should check its
arguments against expected arguments using assertions from
Test::Unit::Assertions. For instance methods I can include
Test::Unit::Assertions in the mock class, that's easy. But how can I
use these assertions in a class method?

  IIUC, the #extend method is what you need, instead of #include

3

Michael Schuerig said:

But how can I use these assertions in a class method?

require 'test/unit'

class Foo
  # This:
  class << self
    include Test::Unit::Assertions
  end
  # OR this:
  extend Test::Unit::Assertions

  def self.do_something
    flunk('Badness')
  end
end

Foo::do_something
__END__

You will need to rescue on the Test::Unit::AssertionFailedError if you
don't want your first failed test taking the whole program down.

Ryan

4

Michael Schuerig wrote:

For unit tests I've written a mock object that should check its
arguments against expected arguments using assertions from
Test::Unit::Assertions. For instance methods I can include
Test::Unit::Assertions in the mock class, that's easy. But how can I
use these assertions in a class method?

Include them in the mock class's singleton class.

--- (untested code, but should work) ---
class MockClass
  include Test::Unit::Assertions

  class << self # To get the singleton class
    include Test::Unit::Assertions
  end

  # Whatever methods need to use the assertions
end

···

---

5

gabriele renzi wrote:

Michael Schuerig ha scritto:

For unit tests I've written a mock object that should check its
arguments against expected arguments using assertions from
Test::Unit::Assertions. For instance methods I can include
Test::Unit::Assertions in the mock class, that's easy. But how can I
use these assertions in a class method?

  IIUC, the #extend method is what you need, instead of #include

Yes, thanks, that is it. I've found a short note to that effect on p.385
of PickAxe2, also.

Michael

···

--
Michael Schuerig Most people would rather die than think.
mailto:michael@schuerig.de In fact, they do.
Michael Schürig | Sentenced to making sense --Bertrand Russell

6

Ryan Leavengood wrote:

You will need to rescue on the Test::Unit::AssertionFailedError if you
don't want your first failed test taking the whole program down.

No, that's not a problem. I'm using the class only in unit tests where
Test::Unit handles these things. It's just a mock object that poses for
some other class and only checks that calls are as expected.

Michael

···

--
Michael Schuerig They tell you that the darkness
mailto:michael@schuerig.de Is a blessing in disguise
Michael Schürig | Sentenced to making sense --Janis Ian, From Me To You

7

Charles Steinman wrote:

Michael Schuerig wrote:

For unit tests I've written a mock object that should check its
arguments against expected arguments using assertions from
Test::Unit::Assertions. For instance methods I can include
Test::Unit::Assertions in the mock class, that's easy. But how can I
use these assertions in a class method?

Include them in the mock class's singleton class.

--- (untested code, but should work) ---
class MockClass
  include Test::Unit::Assertions

  class << self # To get the singleton class
    include Test::Unit::Assertions
  end

  # Whatever methods need to use the assertions
end
---

Thanks, yes, that works, too. I'll need to work with the Ruby object
model some more to become really comfortable with it.

Michael

···

--
Michael Schuerig Airtight arguments have
mailto:michael@schuerig.de vacuous conclusions.
Michael Schürig | Sentenced to making sense --A.O. Rorty, Explaining Emotions

8

Michael Schuerig wrote:

Charles Steinman wrote:

Michael Schuerig wrote:

For unit tests I've written a mock object that should check its
arguments against expected arguments using assertions from
Test::Unit::Assertions. For instance methods I can include
Test::Unit::Assertions in the mock class, that's easy. But how can I
use these assertions in a class method?

Include them in the mock class's singleton class.

--- (untested code, but should work) ---
class MockClass
include Test::Unit::Assertions

class << self # To get the singleton class
   include Test::Unit::Assertions
end

# Whatever methods need to use the assertions
end
---

Thanks, yes, that works, too. I'll need to work with the Ruby object
model some more to become really comfortable with it.

Using #include on the class's signleton class is the same as using
#extend on the class itself, IIRC, so it's not really as confusing as it
sounds at first :slight_smile:

9

Joel VanderWerf <vjoel@path.berkeley.edu> writes:

Using #include on the class's signleton class is the same as using
#extend on the class itself, IIRC

Exactly.

   void
   rb_extend_object(obj, module)
       VALUE obj, module;
   {
       rb_include_module(rb_singleton_class(obj), module);
   }

···

--
Daniel Brockman <daniel@brockman.se>