Fix prefix handling to make update_counter work correctly

 - also fix increment/decrement of array values

lib/statsd.rb

@@ -52,24 +52,19 @@ def timing(stat, time = nil, sample_rate = 1)
 
     # +stats+ can be a string or an array of strings
     def increment(stats, sample_rate = 1)
-      if @prefix
-        stats = "#{@prefix}.#{stats}"
-      end
       update_counter stats, 1, sample_rate
     end
 
     # +stats+ can be a string or an array of strings
     def decrement(stats, sample_rate = 1)
-      if @prefix
-        stats = "#{@prefix}.#{stats}"
-      end
       update_counter stats, -1, sample_rate
     end
 
     # +stats+ can be a string or array of strings
     def update_counter(stats, delta = 1, sample_rate = 1)
       stats = Array(stats)
-      send_stats(stats.map { |s| "#{s}:#{delta}|c" }, sample_rate)
+      p = @prefix ? "#{@prefix}." : '' # apply prefix to each
+      send_stats(stats.map { |s| "#{p}#{s}:#{delta}|c" }, sample_rate)
     end
 
     # +stats+ is a hash

spec/statsd_spec.rb

@@ -93,20 +93,34 @@
   describe '#increment' do
     let(:c) { Statsd::Client.new }
 
-    it 'should prepend the prefix if it has one' do
-      c.prefix = 'dev'
-      c.should_receive(:update_counter).with('dev.foo', anything(), anything())
+    it 'should update the counter by 1' do
+      c.should_receive(:update_counter).with('foo', 1, anything())
       c.increment('foo')
     end
   end
 
   describe '#decrement' do
     let(:c) { Statsd::Client.new }
 
+    it 'should update the counter by -1' do
+      c.should_receive(:update_counter).with('foo', -1, anything())
+      c.decrement('foo')
+    end
+  end
+
+  describe '#update_counter' do
+    let(:c) { Statsd::Client.new }
+
     it 'should prepend the prefix if it has one' do
       c.prefix = 'dev'
-      c.should_receive(:update_counter).with('dev.foo', anything(), anything())
-      c.decrement('foo')
+      c.should_receive(:send_stats).with(['dev.foo:123|c'], anything())
+      c.update_counter('foo', 123)
+    end
+
+    it 'should prepend multiple prefixes if it has one' do
+      c.prefix = 'dev'
+      c.should_receive(:send_stats).with(['dev.foo:123|c', 'dev.bar:123|c'], anything())
+      c.update_counter(['foo', 'bar'], 123)
     end
   end