Fix Arguments to_s

spec/spectator/mocks/arguments_spec.cr

@@ -44,7 +44,7 @@ Spectator.describe Spectator::Arguments do
     subject { arguments.to_s }
 
     it "formats the arguments" do
-      is_expected.to eq("(42, \"foo\", bar: \"baz\", qux: 123)")
+      is_expected.to eq("(42, \"foo\", *splat: {:x, :y, :z}, bar: \"baz\", qux: 123)")
     end
 
     context "when empty" do

src/spectator/mocks/arguments.cr

@@ -92,16 +92,15 @@ module Spectator
 
       # Add the splat arguments.
       if (extra = @extra) && !extra.empty?
-        if splat = @splat_name
-          io << splat << ": {"
-        end
         io << ", " unless positional.empty?
+        if splat = @splat_name
+          io << '*' << splat << ": {"
+        end
         extra.each_with_index do |arg, i|
           io << ", " if i > 0
           arg.inspect(io)
         end
         io << '}' if @splat_name
-        io << ", " unless kwargs.empty?
       end
 
       # Add the keyword arguments.