Added click tracking and tests for it

lib/snogmetrics.rb

@@ -68,6 +68,17 @@ def identify(identity)
       end
     end
 
+    # The equivalent of the `KM.trackClick` method of the JavaScript API. The first
+    # argument should be a selector (a tag id or class name). Furthermore you can
+    # pass either an event name, an event name and a hash of properties, or only
+    # a hash of properties.
+    def trackClick(selector, *args)
+      raise 'Not enough arguments' if args.size == 0
+      raise 'Too many arguments' if args.size > 2
+
+      queue << ['trackClick', selector, *args]
+    end
+
     # Register which variant the user saw in an A/B test.
     def set(experiment, variant)
       queue << ['set', experiment, variant]

spec/snogmetrics_spec.rb

@@ -58,6 +58,35 @@ def self.production?
     end
   end
 
+  describe '#trackClick' do
+    it 'will output code that pushes an event with the specified name and properties' do
+      @context.km.trackClick('tagid', 'hello world', :foo => 'bar')
+      @context.km.js.should include('_kmq.push(["trackClick","tagid","hello world",{"foo":"bar"}]);')
+    end
+
+    it 'will output code that pushes an event with name only' do
+      @context.km.trackClick('tagid', 'foo')
+      @context.km.js.should include('_kmq.push(["trackClick","tagid","foo"]);')
+    end
+
+    it 'will output code that pushes an event with properties only' do
+      @context.km.trackClick('tagid', {:foo => 'bar', :plink => :plonk})
+      @context.km.js.should match(%r#_kmq.push\(\["trackClick","tagid",\{(?:"foo":"bar","plink":"plonk"|"plink":"plonk","foo":"bar")\}\]\)#)
+    end
+
+    it 'complains if called without arguments' do
+      running { @context.km.trackClick }.should raise_error
+    end
+
+    it 'complains if called with selector only' do
+      running { @context.km.trackClick('tagid') }.should raise_error
+    end
+
+    it 'complains if called with more than three arguments' do
+      running { @context.km.trackClick('tagid', 'hello world', {:foo => 'bar'}, '12') }.should raise_error
+    end
+  end
+
   describe '#identify' do
     it 'will output code that pushes an identify call with the provided identity' do
       @context.km.identify('Phil')