Add conversion methods to Twitter::NullObject

lib/twitter/null_object.rb

@@ -1,9 +1,12 @@
+require 'forwardable'
+
 module Twitter
   class NullObject
-    # @return [TrueClass] This method always returns true.
-    def nil?
-      true
-    end
+    extend Forwardable
+    def_instance_delegators :nil, :nil?, :to_a, :to_c, :to_c, :to_f, :to_h,
+                            :to_i, :to_r, :to_s
+    alias_method :to_ary, :to_a
+    alias_method :to_str, :to_s
 
     # @return [Twitter::NullObject] This method always returns self.
     def method_missing(*args, &block)

spec/twitter/null_object_spec.rb

@@ -2,25 +2,88 @@
 
 describe Twitter::NullObject do
 
-  before do
-    @null_object = Twitter::NullObject.new
-  end
-
   describe '#nil?' do
     it 'returns true' do
-      expect(@null_object.nil?).to be true
+      expect(subject.nil?).to be true
+    end
+  end
+
+  describe '#to_a' do
+    it 'returns an empty array' do
+      expect(subject.to_a).to be_an Array
+      expect(subject.to_a).to be_empty
+    end
+  end
+
+  describe '#to_ary' do
+    it 'returns an empty array' do
+      expect(subject.to_ary).to be_an Array
+      expect(subject.to_ary).to be_empty
+    end
+  end
+
+  if RUBY_VERSION >= '1.9'
+    describe '#to_c' do
+      it 'returns zero as a complex number' do
+        expect(subject.to_c).to be_a Complex
+        expect(subject.to_c).to be_zero
+      end
+    end
+
+    describe '#to_r' do
+      it 'returns zero as a rational number' do
+        expect(subject.to_r).to be_a Rational
+        expect(subject.to_r).to be_zero
+      end
+    end
+  end
+
+  if RUBY_VERSION >= '2.0'
+    describe '#to_h' do
+      it 'returns an empty hash' do
+        expect(subject.to_h).to be_a Hash
+        expect(subject.to_h).to be_empty
+      end
+    end
+  end
+
+  describe '#to_f' do
+    it 'returns zero as a floating point number' do
+      expect(subject.to_f).to be_a Float
+      expect(subject.to_f).to be_zero
+    end
+  end
+
+  describe '#to_i' do
+    it 'returns zero' do
+      expect(subject.to_i).to be_an Integer
+      expect(subject.to_i).to be_zero
+    end
+  end
+
+  describe '#to_s' do
+    it 'returns an empty string' do
+      expect(subject.to_s).to be_a String
+      expect(subject.to_s).to be_empty
+    end
+  end
+
+  describe '#to_str' do
+    it 'returns an empty string' do
+      expect(subject.to_str).to be_a String
+      expect(subject.to_str).to be_empty
     end
   end
 
   describe 'calling any method' do
     it 'returns self' do
-      expect(@null_object.any).to equal @null_object
+      expect(subject.any).to equal subject
     end
   end
 
   describe '#respond_to?' do
     it 'returns true' do
-      expect(@null_object.respond_to?(:any)).to be true
+      expect(subject.respond_to?(:any)).to be true
     end
   end