Initial change to MatchData

src/spectator/expectations/expectation.cr

@@ -6,10 +6,9 @@ module Spectator::Expectations
     # The *negated* flag should be true if the expectation is inverted.
     # These options are mutually-exclusive in this context.
     # Don't flip the value of *matched* because *negated* is true.
-    # The *partial* and the *matcher* arguments should reference
-    # the actual and expected result respectively.
-    def initialize(@matched : Bool, @negated : Bool,
-                   @partial : ExpectationPartial, @matcher : Matchers::Matcher)
+    # The *match_data* is the value returned by `Spectator::Matcher#match`
+    # when the expectation was evaluated.
+    def initialize(@matched : Bool, @negated : Bool, @match_data : MatchData)
     end
 
     # Indicates whether the expectation was satisifed.
@@ -22,22 +21,12 @@ module Spectator::Expectations
 
     # Text that indicates the condition that must be met for the expectation to be satisifed.
     def expected_message
-      @negated ? negated_message : message
+      @negated ? @match_data.negated_message : @match_data.message
     end
 
     # Text that indicates what the outcome was.
     def actual_message
-      satisfied? ? message : negated_message
-    end
-
-    # Describes the condition that must be met for the expectation to be satisifed.
-    private def message
-      @matcher.message(@partial)
-    end
-
-    # Describes the condition under which the expectation won't be satisifed.
-    private def negated_message
-      @matcher.negated_message(@partial)
+      satisfied? ? @match_data.message : @match_data.negated_message
     end
   end
 end

src/spectator/expectations/expectation_partial.cr

@@ -44,8 +44,8 @@ module Spectator::Expectations
 
     # Evaluates the expectation and returns it.
     private def eval(matcher, negated = false)
-      matched = matcher.match?(self)
-      Expectation.new(matched, negated, self, matcher)
+      match_data = matcher.match(self)
+      Expectation.new(matched, negated, match_data)
     end
 
     # Reports an expectation to the current harness.

src/spectator/matchers/match_data.cr

@@ -0,0 +1,27 @@
+module Spectator::Matchers
+  # Information regarding a expectation parial and matcher.
+  # `Matcher#match` will return a sub-type of this.
+  abstract struct MatchData
+    # Indicates whether the matcher was satisified with the expectation partial.
+    getter? matched : Bool
+
+    # Creates the base of the match data.
+    # The *matched* argument indicates
+    # whether the matcher was satisified with the expectation partial.
+    def initialize(@matched)
+    end
+
+    # Information about the match.
+    # Returned value and type will differ by sub-type,
+    # but all will return a set of key-value pairs.
+    abstract def values
+
+    # Describes the condition that satisfies the matcher.
+    # This is informational and displayed to the end-user.
+    abstract def message : String
+
+    # Describes the condition that won't satsify the matcher.
+    # This is informational and displayed to the end-user.
+    abstract def negated_message : String
+  end
+end

src/spectator/matchers/matcher.cr

@@ -14,14 +14,6 @@ module Spectator::Matchers
 
     # Determines whether the matcher is satisfied with the value given to it.
     # True is returned if the match was successful, false otherwise.
-    abstract def match?(partial) : Bool
-
-    # Describes the condition that satisfies the matcher.
-    # This is informational and displayed to the end-user.
-    abstract def message(partial) : String
-
-    # Describes the condition that won't satsify the matcher.
-    # This is informational and displayed to the end-user.
-    abstract def negated_message(partial) : String
+    abstract def match(partial) : MatchData
   end
 end

src/spectator/matchers/nil_matcher.cr

@@ -9,22 +9,40 @@ module Spectator::Matchers
       super("nil?")
     end
 
-    # Determines whether the matcher is satisfied with the value given to it.
-    # True is returned if the match was successful, false otherwise.
-    def match?(partial)
-      partial.actual.nil?
+    # Determines whether the matcher is satisfied with the partial given to it.
+    # `MatchData` is returned that contains information about the match.
+    def match(partial)
+      actual = partial.actual
+      matched = actual.nil?
+      MatchData.new(matched, actual, partial.label)
     end
 
-    # Describes the condition that satisfies the matcher.
-    # This is informational and displayed to the end-user.
-    def message(partial)
-      "Expected #{partial.label} to be nil"
-    end
+    # Match data specific to this matcher.
+    private struct MatchData(T) < MatchData
+      # Creates the match data.
+      def initialize(matched, @actual : T, @expected_label : String)
+        super(matched)
+      end
 
-    # Describes the condition that won't satsify the matcher.
-    # This is informational and displayed to the end-user.
-    def negated_message(partial)
-      "Expected #{partial.label} to not be nil"
+      # Information about the match.
+      def values
+        {
+          expected: nil,
+          actual:   @actual,
+        }
+      end
+
+      # Describes the condition that satisfies the matcher.
+      # This is informational and displayed to the end-user.
+      def message
+        "#{@expected_label} is nil"
+      end
+
+      # Describes the condition that won't satsify the matcher.
+      # This is informational and displayed to the end-user.
+      def negated_message
+        "#{@expected_label} is not nil"
+      end
     end
   end
 end