Fix value negation of attribute matcher

src/spectator/matchers/attributes_matcher.cr

@@ -39,7 +39,7 @@ module Spectator::Matchers
     def negated_match(actual : TestExpression(T)) : MatchData forall T
       snapshot = snapshot_values(actual.value)
       if match?(snapshot)
-        FailedMatchData.new("#{actual.label} has attributes #{expected.label}", **values(snapshot))
+        FailedMatchData.new("#{actual.label} has attributes #{expected.label}", **negated_values(snapshot))
       else
         SuccessfulMatchData.new
       end
@@ -79,5 +79,17 @@ module Spectator::Matchers
       }
       {% end %}
     end
+
+    # Produces the tuple for the failed negated match data from a snapshot of the attributes.
+    private def negated_values(snapshot)
+      {% begin %}
+      {
+        {% for attribute in ExpectedType.keys %}
+        {{"expected " + attribute.stringify}}: "Not #{expected.value[{{attribute.symbolize}}].inspect}",
+        {{"actual " + attribute.stringify}}:   snapshot[{{attribute.symbolize}}].inspect,
+        {% end %}
+      }
+      {% end %}
+    end
   end
 end