Use label (expression string) instead of value

src/spectator/expectation.cr

@@ -2,7 +2,7 @@ require "./matchers/matcher"
 
 module Spectator
   class Expectation(T)
-    private getter label : String
+    protected getter label : String
     getter actual : T
 
     protected def initialize(@label : String, @actual : T)

src/spectator/matchers/equality_matcher.cr

@@ -12,11 +12,11 @@ module Spectator
       end
 
       def message(expectation : Expectation) : String
-        "Expected #{expectation.actual} to equal #{@expected} (using ==)"
+        "Expected #{expectation.label} to equal #{label} (using ==)"
       end
 
       def negated_message(expectation : Expectation) : String
-        "Expected #{expectation.actual} to not equal #{@expected} (using ==)"
+        "Expected #{expectation.label} to not equal #{label} (using ==)"
       end
     end
   end