Utils#deprecate only prints each warning once, and has working specs.

lib/koala/utils.rb

@@ -1,10 +1,13 @@
 module Koala
   module Utils
+
+    DEPRECATION_PREFIX = "KOALA: Deprecation warning: "
     def self.deprecate(message)
-      begin
-        send(:warn, "KOALA: Deprecation warning: #{message}")
-      rescue Exception => err
-        puts "Unable to issue Koala deprecation warning!  #{err.message}"
+      @posted_deprecations ||= []
+      unless @posted_deprecations.include?(message)
+        # only include each message once
+        Kernel.warn("#{DEPRECATION_PREFIX}#{message}")
+        @posted_deprecations << message
       end
     end
   end

spec/cases/utils_spec.rb

@@ -1,10 +1,34 @@
 require 'spec_helper'
 
 describe Koala::Utils do
-  it "has a deprecate method" do
-    Koala::Utils.should respond_to(:deprecate)
-  end
+  describe "#deprecate" do    
+    before :each do
+      # unstub deprecate so we can test it
+      Koala::Utils.unstub(:deprecate)
+    end
+
+    it "has a deprecation prefix that includes the words Koala and deprecation" do
+      Koala::Utils::DEPRECATION_PREFIX.should =~ /koala/i
+      Koala::Utils::DEPRECATION_PREFIX.should =~ /deprecation/i      
+    end
+
+    it "prints a warning with Kernel.warn" do
+      message = Time.now.to_s + rand.to_s
+      Kernel.should_receive(:warn)
+      Koala::Utils.deprecate(message)
+    end
 
-  # AFAIK there's no way to test that (Kernel.)warn receives the text
-  # Kernel.should_receive(:warn) doesn't seem to work, even though the text gets printed
+    it "prints the deprecation prefix and the warning" do
+      message = Time.now.to_s + rand.to_s
+      Kernel.should_receive(:warn).with(Koala::Utils::DEPRECATION_PREFIX + message)
+      Koala::Utils.deprecate(message)
+    end
+
+    it "only prints each unique message once" do
+      message = Time.now.to_s + rand.to_s
+      Kernel.should_receive(:warn).once
+      Koala::Utils.deprecate(message)
+      Koala::Utils.deprecate(message)
+    end
+  end
 end