```ruby
require 'spec_helper'
module Gisele::Language
  describe Grammar do

    let(:grammar){ Gisele::Language::Grammar }

    def parse(text, rule, consume = true)
      grammar.parse(text, :root => rule, :consume => consume)
    end

    describe 'the task_name rule' do

      it 'parses correct task names' do
        parse('A',         :task_name).should eq('A')
        parse('Diagnosis', :task_name).should eq('Diagnosis')
        parse('TaskName',  :task_name).should eq('TaskName')
      end

      it 'raises on invalid task names' do
        lambda{ parse('not_a_task_name',  :task_name) }.should raise_error(Citrus::ParseError)
      end

    end # task_name

  end
end```

Enhance test coverage for task name.
user
```ruby
require 'spec_helper'
module Gisele::Language
  describe Grammar do

    let(:grammar){ Gisele::Language::Grammar }

    def parse(text, rule, consume = true)
      grammar.parse(text, :root => rule, :consume => consume)
    end

    describe 'the task_name rule' do

      it 'parses correct task names' do
        parse('A',          :task_name).should eq('A')
        parse('Diagnosis',  :task_name).should eq('Diagnosis')
        parse('TaskName',   :task_name).should eq('TaskName')
        parse('Task_Name',  :task_name).should eq('Task_Name')
      end

      it 'raises on invalid task names' do
        lambda{ parse('not_a_task_name',  :task_name) }.should raise_error(Citrus::ParseError)
      end

    end # task_name

  end
end```
assistant