Merge pull request #3 from Yesware/failure-value

Failure value

CHANGELOG.md

@@ -0,0 +1,8 @@
+# deferrable_gratification changes
+
+## v1.0.0
+- Remove the `Fluent` module as the same syntax is available in
+  `EventMachine` 1.0.3.
+- Add `failure_value` to `DeferrableGratification::Primitives` to fail without
+  an exception. Any value may be specified, but the main use is to fail with
+  only an error string.

lib/deferrable_gratification/default_deferrable.rb

@@ -5,7 +5,6 @@ module DeferrableGratification
   # Barebones Deferrable that includes the {DeferrableGratification}
   # extensions:
   #
-  # @see Fluent
   # @see Bothback
   # @see Combinators
   class DefaultDeferrable

lib/deferrable_gratification/primitives.rb

@@ -49,6 +49,16 @@ def failure(exception_class_or_message, message_or_nil = nil)
       end
     end
 
+    # Return a Deferrable which immediately fails with the specified value.
+    # This is useful for failing with the string for an error message instead
+    # of an exception.
+    #
+    # @param value [Object] The value to fail with.
+    # @return [EM::Deferrable] A deferrable that fails with the specified value.
+    def failure_value(value)
+      blank.tap { |d| d.fail(value) }
+    end
+
     # Return a completely uninteresting Deferrable.
     def blank
       DeferrableGratification::DefaultDeferrable.new

spec/deferrable_gratification/primitives_spec.rb

@@ -56,4 +56,33 @@
       it { should fail_with(RangeError, 'you shall not pass!') }
     end
   end
+
+  describe '.failure_value' do
+    describe 'DG.failure_value with a string' do
+      subject { DG.failure_value('i am a string') }
+
+      it 'fails with the specified string' do
+        error = nil
+        subject.errback do |err|
+          error = err
+        end
+
+        error.should == 'i am a string'
+      end
+    end
+
+    describe 'DG.failure_value with an arbitrary object' do
+      let(:obj) { double(Object) }
+      subject { DG.failure_value(obj) }
+
+      it 'fails with the specified object' do
+        error = nil
+        subject.errback do |err|
+          error = err
+        end
+
+        error.should equal obj
+      end
+    end
+  end
 end