Merge pull request #83 from chiting/add-hex-check

Add hexadecimal RGB triplet string format check

lib/rainbow/color.rb

@@ -36,6 +36,11 @@ def self.build(ground, values)
     end
 
     def self.parse_hex_color(hex)
+      unless hex =~ /^#?[a-f0-9]{6}/i
+        raise ArgumentError,
+              "Invalid hexadecimal RGB triplet. Valid format: /^#?[a-f0-9]{6}/i"
+      end
+
       hex = hex.sub(/^#/, '')
       r   = hex[0..1].to_i(16)
       g   = hex[2..3].to_i(16)

spec/unit/color_spec.rb

@@ -37,7 +37,7 @@ module Rainbow
         specify { expect(subject.b).to eq(112) }
       end
 
-      context "when single string given" do
+      context "when single hexadecimal string given" do
         let(:values) { ['#deadcc'] }
 
         it { should be_instance_of(Color::RGB) }
@@ -48,6 +48,14 @@ module Rainbow
         specify { expect(subject.b).to eq(204) }
       end
 
+      context "when single non hexadecimal string given" do
+        let(:values) { ['green'] }
+
+        it 'raises ArgumentError' do
+          expect { subject }.to raise_error(ArgumentError)
+        end
+      end
+
       context "when 2 elements" do
         let(:values) { [1, 2] }