Simplify string (inspect) representation

These types make heavy use of generics and combined types.
Instantiating string representation methods for all possibilities is unecesssary and slows down compilation.

src/spectator/mocks/abstract_arguments.cr

@@ -1,6 +1,11 @@
 module Spectator
   # Untyped arguments to a method call (message).
   abstract class AbstractArguments
+    # Use the string representation to avoid over complicating debug output.
+    def inspect(io : IO) : Nil
+      to_s(io)
+    end
+
     # Utility method for comparing two named tuples ignoring order.
     private def compare_named_tuples(a : NamedTuple, b : NamedTuple)
       a.each do |k, v1|

src/spectator/mocks/double.cr

@@ -101,6 +101,19 @@ module Spectator
       io << _spectator_stubbed_name
     end
 
+    # :ditto:
+    def inspect(io : IO) : Nil
+      {% if anno = @type.annotation(::Spectator::StubbedName) %}
+        io << "#<Double " << {{(anno[0] || :Anonymous.id).stringify}}
+      {% else %}
+        io << "#<Double Anonymous"
+      {% end %}
+
+      io << ":0x"
+      object_id.to_s(io, 16)
+      io << '>'
+    end
+
     # Defines a stub to change the behavior of a method in this double.
     #
     # NOTE: Defining a stub for a method not defined in the double's type has no effect.

src/spectator/mocks/method_call.cr

@@ -30,7 +30,13 @@ module Spectator
 
     # Constructs a string containing the method name and arguments.
     def to_s(io : IO) : Nil
-      io << '#' << method << arguments
+      io << '#' << method
+      arguments.inspect(io)
+    end
+
+    # :ditto:
+    def inspect(io : IO) : Nil
+      to_s(io)
     end
   end
 end