Posts Tagged 'devops'

Testing recipe definitions with chefspec

Last time [1], we wrote chefspec tests to cover the behavior of the nginx::default recipe.  Another component provided by the recipe, is the nginx_site definition.  Similar to the previous approach we cover the definition’s resources for each possible track the recipe can go through.  The following is the output when the specs succeed.

nginx::default
  #nginx_site (definition)
    #enable => true (default)
      should execute command "/usr/sbin/nxensite foo"
      should notify "service[nginx]" and "reload"
    #enable => false
      should execute command "/usr/sbin/nxdissite foo"
      should notify "service[nginx]" and "reload"

To go about covering the behavior, we start driving TDD by creating failing specs staring with the default case:

context "#nginx_site (definition)" do
  context "#enable => true (default)" do
    it { expect(chef_run).to execute_command "/usr/sbin/nxensite foo" }
    it do
      expect(chef_run.execute("nxensite foo"))
      .to notify("service[nginx]", "reload")
    end
  end
end

The above specs will fail because nginx::default doesn’t to make a nginx_site(“foo”) call.  In minitest or test-kitchen, the approach was to create a test recipe that will conduct this integration test.  However, for isolated chefspecs, this is too heavy weight.  Code diving into the Chef 11.4.4 documentation and code [2], every recipe file is loaded by an instance_eval call on Recipe objects.  Hence we can make this approach to inject a fake recipe.  Below, we created a recipe called “nginx_spec::default” with using the existing run context from the “nginx::default” run.

def fake_recipe(run, &block)
  recipe = Chef::Recipe.new("nginx_spec", "default", run.run_context)
  recipe.instance_eval(&block)
end

# call to the spec example

recipe = fake_recipe(chef_run) do
  nginx_site "foo" do
    enable enabled
  end
end

Next, we create a new ChefSpec::ChefRunner instance by appending our internally-created “nginx_spec::default” recipe to the existing “nginx::default” run.  For this we monkey-patch chefspec to converge the added recipe:

class ChefSpec::ChefRunner
  def append(recipe)
    runner = Chef::Runner.new(recipe.run_context)
    runner.converge
    self
  end
end

# usage in our examples:
new_run = chef_run.append(recipe)

Now we can change our specs to use this new runner context instead to make our expectations.  Below is the whole context that makes the spec pass:

context "#enable => true (default)" do
  let(:run) do
    recipe = fake_recipe(chef_run) do
      nginx_site "foo"
    end
    chef_run.append(recipe)
  end

  it { expect(run).to execute_command "/usr/sbin/nxensite foo" }

  it do
    expect(run.execute("nxensite foo"))
    .to notify("service[nginx]", "reload")
  end
end

And now we have the nginx_site definition covered.  I made commits on the changes in my fork [3] of the opscode cookbook.  Although the approach is useful, this intrusive monkey-patching to chefspec (which is itself a monkey-patch on chef) shows why folks at Opscode recommend to use LWRPS into new recipe development as you can monitor the state of the new resource itself.  With definitions, you have to track the state of the resources made inside the definition action and provide the necessary spec.  This also has implications when you are driving the recipes via TDD to use the nginx_site definition.  I will cover testing that in another post.

  1. https://amespinosa.wordpress.com/2013/05/01/creating-fast-spec-coverage-on-legacy-recipes/
  2. http://rubydoc.info/gems/chef/11.4.4/Chef/DSL/IncludeRecipe#load_recipe-instance_method
  3. https://github.com/aespinosa/cookbook-nginx/commit/81ca51fcfcf8612101486371b3d46bc246fba322
広告

creating fast spec coverage on legacy recipes

As techniques in testing Chef recipes are still evolving, most of use inherit large untested cookbook codebases from eons ago (translates to a few months in Chef’s community speed).   After watching Chefconf 2013 livestreams, I decided to give chefspec [3] a try.  However, most of the write-ups about chefspec cover pretty basic.  Here, I will write how I covered our legacy chef repository with fast tests.  For this example, I will be writing coverage for opscode’s nginx recipe [1] .

First we begin by covering examples for all resources that gets created by default.

describe 'nginx::default' do
  it "loads the ohai plugin"
  it "starts the service"
end

Then, we create contexts for each test case in the recipe logic.

describe 'nginx::default' do
  it "loads the ohai plugin"

  it "builds from source when specified"

  context "install method is by package" do
    context "when the platform is redhat-based" do
      it "includes the yum::epel recipe if the source is epel"
      it "includes the nginx::repo recipe if the source is not epel"
    end
    it "installs the package"
    it "enables the service"
    it "includes common configurations"
  end

  it "starts the service"
end

Now we have a general idea of what tests to write from the rspec documentation run:

 rspec spec/default_spec.rb

nginx::default
  loads the ohai plugin (PENDING: Not yet implemented)
  builds from source when specified (PENDING: Not yet implemented)
  starts the service (PENDING: Not yet implemented)
  install method is by package
    installs the package (PENDING: Not yet implemented)
    enables the service (PENDING: Not yet implemented)
    includes common configurations (PENDING: Not yet implemented)
    when the platform is redhat-based
      includes the yum::epel recipe if the source is epel (PENDING: Not yet implemented)
      includes the nginx::repo recipe if the source is not epel (PENDING: Not yet implemented)

Pending:
  nginx::default loads the ohai plugin
    # Not yet implemented
    # ./spec/default_spec.rb:4
  nginx::default builds from source when specified
    # Not yet implemented
    # ./spec/default_spec.rb:6
  nginx::default starts the service
    # Not yet implemented
    # ./spec/default_spec.rb:18
  nginx::default install method is by package installs the package
    # Not yet implemented
    # ./spec/default_spec.rb:13
  nginx::default install method is by package enables the service
    # Not yet implemented
    # ./spec/default_spec.rb:14
  nginx::default install method is by package includes common configurations
    # Not yet implemented
    # ./spec/default_spec.rb:15
  nginx::default install method is by package when the platform is redhat-based includes the yum::epel recipe if the source is epel
    # Not yet implemented
    # ./spec/default_spec.rb:10
  nginx::default install method is by package when the platform is redhat-based includes the nginx::repo recipe if the source is not epel
    # Not yet implemented
    # ./spec/default_spec.rb:11

Finished in 0.00977 seconds
8 examples, 0 failures, 8 pending

Progress can be found in [2] where i tested everything.  Next I will be writing on how I tested the nginx nginx_site definitions.

  1. http://community.opscode.com/cookbooks/nginx
  2. https://github.com/aespinosa/cookbook-nginx
  3. https://github.com/acrmp/chefspec
  4. https://www.destroyallsoftware.com/screencasts/catalog/untested-code-part-1-introduction

Disclaimer: I came from an xUnit-testing background so I maybe interchanging “test cases” with “examples” and other purist stuff.  Also I may need to proof read on how my spec examples speak.