UPDATE 2015-06-26: Now re-tests all specs when testing plugins

We want to be able to test multiple implementations of the same function. For example, nmatrix has an internal implementation of getrf (used for calculating the determinant, among other things), but nmatrix-atlas overrides this with its own version of getrf which uses the ATLAS implementation. We want to test both of these.

There's no way to tell rspec: "run this bunch of specs, then require "nmatrix/atlas", then run this other bunch of specs". It loads all the spec files first, and then starts running the tests. So if one spec file requires nmatrix/atlas, then the ATLAS functions will be available when running all the specs. To avoid this, we make the rake spec task invoke rspec multiple times. After setting up the Rakefile as described here (and also remembering to set test_files in all our gemspecs), we need to add the following to set up the spec task:

require 'rspec/core/rake_task'
require 'rspec/core'
namespace :spec do
  #We need a separate rake task for each plugin, rather than one big task that
  #runs all of the specs. This is because there's no way to tell rspec
  #to run the specs in a certain order with (say) "nmatrix/atlas" require'd
  #for some of the specs, but not for others, without splitting them up like
  spec_tasks = []
  gemspecs.each do |gemspec|
    test_files = gemspec.test_files
    test_files.keep_if { |file| file =~ /_spec\.rb$/ }
    next if test_files.empty?
    spec_tasks << gemspec.name
    RSpec::Core::RakeTask.new(gemspec.name) do |spec|
      spec.pattern = FileList.new(test_files)
  task :all => spec_tasks

task :spec => "spec:all"

This has the desired behavior that if one the of spec sub-tasks fails, the task will fail immediately and the most recent messages on the console will give you the details about the error. It will not continue with the next rspec invocation if the previous one fails.

So the first invocation (testing the core nmatrix plugin) includes all the files in spec/ excluding those in spec/plugins/, and the second invocation (testing the nmatrix-atlas plugin) includes all of the files from the first run plus the files in spec/plugins/atlas/ where atlas_spec.rb is located. In atlas_spec.rb we require 'nmatrix/atlas', so that the second time all tests are run with the nmatrix-atlas plugin active.

Originally I planned to isolate all the specs that could possibly behave differently with nmatrix-atlas, and run only these tests when testing nmatrix-atlas. I eventually decided that it was better just to re-test everything.

Another issue that could arise is if we'd like to use the exact same specs to test equivalent functions. This is easily solved with RSpec's shared examples. So we create a file spec/lapack_shared.rb (since it doesn't end in _spec.rb it won't be included by our rake spec task):

RSpec.shared_examples "LAPACK shared" do
  #getrf spec goes here

And then in spec/plugins/atlas/atlas_spec.rb:

require "./lib/nmatrix/atlas"

require 'lapack_shared'

describe "NMatrix::LAPACK implementation from nmatrix-atlas plugin" do
  include_examples "LAPACK shared"

And something similar in spec/lapack_spec.rb except without the require "./lib/nmatrix/atlas" line. I did this before, but now that the nmatrix-atlas tests runs the entire nmatrix test suite, it's not necessary for the moment.