Merge pull request #1828 from tsion/argumenterror-message

Fix #inspect, #to_s, and #message for ArgumentError

kernel/common/exception.rb

@@ -168,12 +168,15 @@ class ZeroDivisionError < StandardError
 end
 
 class ArgumentError < StandardError
-  def message
-    return @reason_message if @reason_message
-    if @method_name
-      "method '#{@method_name}': given #{@given}, expected #{@expected}"
+  def to_s
+    if @given and @expected
+      if @method_name
+        "method '#{@method_name}': given #{@given}, expected #{@expected}"
+      else
+        "given #{@given}, expected #{@expected}"
+      end
     else
-      "given #{@given}, expected #{@expected}"
+      super
     end
   end
 end

spec/core/exception/arguments_spec.rb

@@ -0,0 +1,9 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+
+describe "ArgumentError" do
+  it "uses its internal message in #inspect" do
+    lambda { 1.+(2, 3) }.should raise_error(ArgumentError) do |e|
+      e.inspect.should == "#<ArgumentError: method '+': given 2, expected 1>"
+    end
+  end
+end

spec/ruby/core/exception/arguments_spec.rb

@@ -4,4 +4,8 @@
   it "is a subclass of StandardError" do
     StandardError.should be_ancestor_of(ArgumentError)
   end
+
+  it "gives its own class name as message if it has no message" do
+    ArgumentError.new.message.should == "ArgumentError"
+  end
 end