Removing an AR class definition, for testing plugins

rubyonrails-talk
1

I'm writing an acts_as_* plugin and am trying to BDD it. Ideally my specs would look like:

describe ActsAsCloneable, " basic cloning" do   load_example_classes   School.class_eval do     acts_as_cloneable   end

  before(:each) do     @old_school = School.create! :name => "Baylake Pines", :city => "Virginia Beach", :guid => "abc123"     @clone = @old_school.build_clone   end

  it "should preserve the attributes" do     @clone.name.should == "Baylake Pines"     @clone.city.should == "Virginia Beach"     @clone.guid.should == "abc123"   end

  it "should not clone the id" do     @clone.id.should be_blank   end end

describe ActsAsCloneable, " while specifying an attribute not to clone" do   load_example_classes   School.class_eval do     acts_as_cloneable :except => :guid   end

  before(:each) do     @old_school = School.create! :name => "Baylake Pines", :city => "Virginia Beach", :guid => "abc123"     @clone = @old_school.build_clone   end

  it "should preserve the regular attributes" do     @clone.name.should == "Baylake Pines"     @clone.city.should == "Virginia Beach"   end

  it "should not clone the specified attribute" do     @clone.guid.should be_blank   end

  it "should not clone the uncloned attribute" do     @clone.guid.should be_blank   end end

load_example_classes is a helper method that just defines the AR::base classes. The undefs would go there too.

Unfortunately what's happening is that the definition from the second spec is being used for the first spec...so when running both specs, the first fails. However if I comment out the second spec, the first one passes.

I've tried using remove_const and Object.remove_class. Neither seems to work. I need to start with a fresh class definition before each description is run...how can I do that?

Pat

2

The main idea behind the solution is classes are constants, knowing that and also that every class inherit from Module, as you guessed remove_const method is the key to do it.

1) If the class you want to remove belongs to main you should do: Object.send :remove_const, 'ClassToRemove'

    acts_as_cloneable   end

  before(:each) do

2) If the class you want to remove is inside a class or module you should do: MyModule.remove_const, 'ClassToRemove' => outside the module/class self.class.send :remove_const, 'ClassToRemove' => inside the module/ class

Assuming you create your test class with an eval inside a test case something like this should work:

class MyTestCase   def setup     eval 'class B; end'   end

  def teardown     self.class.send :remove_const, 'B'   end end

a = MyTestCase.new a.setup ; puts "after setup #{MyTestCase.constants.inspect}" # output ["B"] a.teardown ; puts "after teardown #{MyTestCase.constants.inspect}" # output