assert_file

Asserts a given file exists. You need to supply an absolute path or a path relative to the configured destination:

assert_file "config/environment.rb"

You can also give extra arguments. If the argument is a regexp, it will check if the regular expression matches the given file content. If it's a string, it compares the file with the given string:

assert_file "config/environment.rb", /initialize/

Finally, when a block is given, it yields the file content:

assert_file "app/controllers/products_controller.rb" do |controller|
  assert_instance_method :index, controller do |index|
    assert_match(/Product\.all/, index)
  end
end

assert_directory