Stubbing method with block throws "Illegal Instruction: 4" on OS X 10.7.5

[ericgriffis]

When I attempt to stub a method using a block to generate a return value, rspec prints "Illegal Instruction: 4" and exits. According to the second answer to this question, this means that some binary instruction is invalid on the executing OS (I'm running rspec-rails 2.13.1 on OS X 10.7.5).

Has anyone else noticed this problem? Is this a problem internal to rspec, rspec-rails, or rails, or could it be something else I have installed?

[JonRowe]

Can you provide a code sample to reproduce this? And we'd need you to be running the latest version of RSpec (2.14) and let us know what version of Ruby you're running.

[ericgriffis]

I am running rpsec-rails 2.13.1 and ruby 1.9.3p392, sorry for leaving that out before.

In attempting to find the simplest code that reproduces the error, I noticed a strange contingency on this behavior.

With the following code, rspec will print one failure then "Illegal instruction: 4" and exit:

describe "test" do
  before :each do
    Listing.stub(:new).and_return do
      FactoryGirl.build(:listing)
    end
  end

  describe "stub" do
    it "should do foo" do
      @listing = Listing.new
    end
    it "should do bar" do
      @listing = Listing.new
    end
  end
end

Here is the command line output:

FIllegal instruction: 4

However, with the following code, rspec will complete successfully, printing a different error:

describe "test" do
  before :each do
    Listing.stub(:new).and_return do
      FactoryGirl.build(:listing)
    end
  end

  describe "stub" do
    it "should do foo" do
      @listing = Listing.new
    end
  end
end

Here is the command line output for this code:

F

Failures:

  1) test stub should do foo
     Failure/Error: Unable to find matching line from backtrace
     SystemStackError:
       stack level too deep
     # /Users/ericgriffis/.rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/activesupport-3.2.13/lib/active_support/core_ext/class/attribute.rb:81

Note that the only difference between the two code blocks is that the former runs an identical test on the same (stubbed) method twice.

Thanks for looking into this; it's really got me stumped.

[xaviershay]

First, you need to do this:

listing = FactoryGirl.build(:listing)
Listing.stub(:new).and_return(listing)

What you had was equivalent to...

Object.stub(:new).and_return do
  Object.new
end

... which can't work because new has already been stubbed by the time you call it, hence the SystemStackError.

I haven't repro'd the illegal instruction part yet though.

[myronmarston]

I suspect that the illegal instruction has to do with how @ericgriffis's ruby interpreter was compiled, and we probably won't be able to repro it on our machines.

[xaviershay]

Don't think there's any other action here for us then. @ericgriffis please re-open if you're not satisfied :)

[JonRowe]

Yeah I suspect this is an artefact of the build/new relationship internally and doing something weird in your code / build of ruby. This isn't an RSpec issue.