Update GreaterThanEqualMatcher to use MatchData

Add PrefixedValue type to help convey values better (without string
concat).

src/spectator/matchers/greater_than_equal_matcher.cr

@@ -5,27 +5,48 @@ module Spectator::Matchers
   # The values are compared with the >= operator.
   struct GreaterThanEqualMatcher(ExpectedType) < ValueMatcher(ExpectedType)
     # 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 >= expected
+    private def match?(actual)
+      actual >= expected
     end
 
     # Determines whether the matcher is satisfied with the partial given to it.
     # `MatchData` is returned that contains information about the match.
-    def match(partial) : MatchData
-      raise NotImplementedError.new("#match")
+    def match(partial)
+      values = ExpectedActual.new(partial, self)
+      MatchData.new(match?(values.actual), values)
     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 greater than or equal to #{label} (using >=)"
-    end
+    # Match data specific to this matcher.
+    private struct MatchData(ExpectedType, ActualType) < MatchData
+      # Creates the match data.
+      def initialize(matched, @values : ExpectedActual(ExpectedType, ActualType))
+        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 greater than or equal to #{label} (using >=)"
+      # Information about the match.
+      def values
+        {
+          expected: PrefixedValue.new(">=", @values.expected),
+          actual:   PrefixedValue.new(actual_operator, @values.actual),
+        }
+      end
+
+      # Textual operator for the actual value.
+      private def actual_operator
+        matched? ? ">=" : "<"
+      end
+
+      # Describes the condition that satisfies the matcher.
+      # This is informational and displayed to the end-user.
+      def message
+        "#{@values.actual_label} is greater than or equal to #{@values.expected_label} (using >=)"
+      end
+
+      # Describes the condition that won't satsify the matcher.
+      # This is informational and displayed to the end-user.
+      def negated_message
+        "#{@values.actual_label} is less than #{@values.expected_label} (using >=)"
+      end
     end
   end
 end

src/spectator/matchers/prefixed_value.cr

@@ -0,0 +1,18 @@
+module Spectator::Matchers
+  # Prefixes (for output formatting) an actual or expected value.
+  private struct PrefixedValue(T)
+    # Value being prefixed.
+    getter value : T
+
+    # Creates the prefixed value.
+    def initialize(@prefix : String, @value : T)
+    end
+
+    # Outputs the formatted value with a prefix.
+    def to_s(io)
+      io << @prefix
+      io << ' '
+      io << @value
+    end
+  end
+end