Add spec for including only *.css files

Author: Adam Garstka

spec/cc/engine/csslint_spec.rb

@@ -0,0 +1,28 @@
+require 'cc/engine/csslint'
+require 'tmpdir'
+
+module CC
+  module Engine
+    describe CSSlint do
+      let(:code) { Dir.mktmpdir }
+      let(:lint) { CSSlint.new(directory: code, io: nil, engine_config: {}) }
+      let(:content) { '#id { color: red; }' }
+
+      describe '#run' do
+        it 'analyzes *.css files' do
+          create_source_file('foo.css', content)
+          expect{ lint.run }.to output(/Don't use IDs in selectors./).to_stdout
+        end
+
+        it "doesn't analyze *.scss files" do
+          create_source_file('foo.scss', content)
+          expect{ lint.run }.to_not output.to_stdout
+        end
+
+        def create_source_file(path, content)
+          File.write(File.join(code, path), content)
+        end
+      end
+    end
+  end
+end