Merge pull request capistrano#84 from prevailhs/opt-out-no-matching-s…

…ervers

Update Servers#find_servers to not throw exception on unknown roles

lib/capistrano/configuration/servers.rb

@@ -54,13 +54,14 @@ def find_servers(options={})
             filter_server_list(hosts.uniq)
           end
         else
-					roles = role_list_from(ENV['ROLES'] || options[:roles] || self.roles.keys)
-					roles = roles & Array(options[:roles]) if preserve_roles && !options[:roles].nil?
+          roles = role_list_from(ENV['ROLES'] || options[:roles] || self.roles.keys)
+          roles = roles & Array(options[:roles]) if preserve_roles && !options[:roles].nil?
 
           only   = options[:only] || {}
           except = options[:except] || {}
 
-          servers = roles.inject([]) { |list, role| list.concat(self.roles[role]) }
+          # If we don't have a def for a role it means its bogus, skip it so higher level can handle
+          servers = roles.inject([]) { |list, role| list.concat(self.roles[role] || []) }
           servers = servers.select { |server| only.all? { |key,value| server.options[key] == value } }
           servers = servers.reject { |server| except.any? { |key,value| server.options[key] == value } }
 
@@ -103,7 +104,6 @@ def role_list_from(roles)
         roles = build_list(roles)
         roles.map do |role|
           role = String === role ? role.strip.to_sym : role
-          raise ArgumentError, "unknown role `#{role}'" unless self.roles.key?(role)
           role
         end
       end

test/configuration/servers_test.rb

@@ -39,11 +39,11 @@ def test_task_with_single_role_should_apply_only_to_that_role
     assert_equal %w(web1 web2).sort, @config.find_servers_for_task(task).map { |s| s.host }.sort
   end
 
-  def test_task_with_unknown_role_should_raise_exception
+  # NOTE Rather than throw an error, as it used to, we return an
+  #  empty array so that if a task is okay with a missing role it can continue on
+  def test_task_with_unknown_role_should_return_empty_array
     task = new_task(:testing, @config, :roles => :bogus)
-    assert_raises(ArgumentError) do
-      @config.find_servers_for_task(task)
-    end
+    assert_equal [], @config.find_servers_for_task(task)
   end
 
   def test_task_with_hosts_option_should_apply_only_to_those_hosts