Testing for warnings

ruby-talk
1

Is there a way of asserting that a warning is raised in a unit test? So I could write something like:

assert_warns "Blah blah" do function_that_warns(foo) end

I can't seem to find anything in the test/unit docs, but it seems like something that would be relatively common to test for...

Alex Gutteridge

Bioinformatics Center
Kyoto University

2

You may try to write that yourself by replacing Kernel#warn, though
this way you cannot check warnings from C code. Alternatively you
could replace/capture $stderr/STDERR and look for warnings there.

···

On 7/2/07, Alex Gutteridge <alexg@kuicr.kyoto-u.ac.jp> wrote:

Is there a way of asserting that a warning is raised in a unit test?
So I could write something like:

assert_warns "Blah blah" do function_that_warns(foo) end

I can't seem to find anything in the test/unit docs, but it seems
like something that would be relatively common to test for...

3

I specifically need to check for warnings from C code so replacing Kernel#warn won't work. I will try hooking into STDERR though - thanks for the idea.

Alex Gutteridge

Bioinformatics Center
Kyoto University

···

On 3 Jul 2007, at 06:23, Jano Svitok wrote:

On 7/2/07, Alex Gutteridge <alexg@kuicr.kyoto-u.ac.jp> wrote:

Is there a way of asserting that a warning is raised in a unit test?
So I could write something like:

assert_warns "Blah blah" do function_that_warns(foo) end

I can't seem to find anything in the test/unit docs, but it seems
like something that would be relatively common to test for...

You may try to write that yourself by replacing Kernel#warn, though
this way you cannot check warnings from C code. Alternatively you
could replace/capture $stderr/STDERR and look for warnings there.

4

Possibly make use of Mocha or another mocking framework?

class Foo
  def bar
    warn "baz"
  end
end

require "test/unit"
require "rubygems"
require "mocha"

class TestFoo < Test::Unit::TestCase

  def test_bar_should_warn
    a = Foo.new
    a.expects(:warn).with("baz")
    a.bar
  end

end

···

On 7/2/07, Alex Gutteridge <alexg@kuicr.kyoto-u.ac.jp> wrote:

I specifically need to check for warnings from C code so replacing
Kernel#warn won't work. I will try hooking into STDERR though -
thanks for the idea.