better error message handling + keep the throws JS object as error.value

lib/rhino/error.rb

@@ -5,14 +5,8 @@ module Rhino
     
     def initialize(native)
       @native = native # NativeException wrapping a Java Throwable
-    end
-
-    def message
-      cause ? cause.details : @native.to_s
-    end
-    
-    def to_s
-      super
+      message = value ? value : ( cause ? cause.details : @native )
+      super(message)
     end
     
     # most likely a Rhino::JS::JavaScriptException
@@ -20,6 +14,17 @@ module Rhino
       @native.respond_to?(:cause) ? @native.cause : nil
     end
 
+    def value
+      return @value if defined?(@value)
+      if cause.respond_to?(:value) # e.g. JavaScriptException.getValue
+        @value = cause.value
+      elsif ( unwrap = self.unwrap ) && unwrap.respond_to?(:value)
+        @value = unwrap.value
+      else
+        @value = nil
+      end
+    end
+    
     def unwrap
       return @unwrap if defined?(@unwrap)
       cause = self.cause

spec/rhino/error_spec.rb

@@ -6,9 +6,9 @@ describe Rhino::JSError do
     js_error = Rhino::JSError.new 'an error message'
     lambda { js_error.to_s && js_error.inspect }.should_not raise_error
     
-    js_error.cause.should be_nil
+    js_error.cause.should be nil
     js_error.message.should == 'an error message'
-    js_error.javascript_backtrace.should be_nil
+    js_error.javascript_backtrace.should be nil
   end
   
   it "might wrap a RhinoException wrapped in a NativeException like error" do
@@ -30,9 +30,34 @@ describe Rhino::JSError do
     js_error = Rhino::JSError.new native_error_class.new(rhino_e)
     lambda { js_error.to_s && js_error.inspect }.should_not raise_error
     
-    js_error.cause.should be(rhino_e)
+    js_error.cause.should be rhino_e
     js_error.message.should == '42'
-    js_error.javascript_backtrace.should_not be_nil
+    js_error.javascript_backtrace.should_not be nil
+  end
+  
+  it "keeps the thrown javascript object value" do
+    begin
+      Rhino::Context.eval "throw { foo: 'bar' }"
+    rescue => e
+      e.should be_a(Rhino::JSError)
+      e.value.should be_a(Rhino::JS::NativeObject)
+      e.value['foo'].should == 'bar'
+      e.value.should == e.message
+    else
+      fail "expected to rescue"
+    end
+  end
+
+  it "keeps the thrown javascript string value" do
+    begin
+      Rhino::Context.eval "throw 'mehehehe'"
+    rescue => e
+      e.should be_a(Rhino::JSError)
+      e.value.should == 'mehehehe'
+      e.value.should == e.message
+    else
+      fail "expected to rescue"
+    end
   end
   
 end