Update StartWithMatcher to use MatchData

spec/matchers/start_with_matcher_spec.cr

@@ -1,7 +1,9 @@
 require "../spec_helper"
 
 describe Spectator::Matchers::StartWithMatcher do
-  describe "#match?" do
+  describe "#match" do
+    context "returned MatchData" do
+      describe "#matched?" do
         context "with a String" do
           context "against a matching string" do
             it "is true" do
@@ -9,7 +11,8 @@ describe Spectator::Matchers::StartWithMatcher do
               start = "foo"
               partial = new_partial(value)
               matcher = Spectator::Matchers::StartWithMatcher.new(start)
-          matcher.match?(partial).should be_true
+              match_data = matcher.match(partial)
+              match_data.matched?.should be_true
             end
 
             context "not at start" do
@@ -18,7 +21,8 @@ describe Spectator::Matchers::StartWithMatcher do
                 start = "bar"
                 partial = new_partial(value)
                 matcher = Spectator::Matchers::StartWithMatcher.new(start)
-            matcher.match?(partial).should be_false
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_false
               end
             end
           end
@@ -29,7 +33,8 @@ describe Spectator::Matchers::StartWithMatcher do
               start = "baz"
               partial = new_partial(value)
               matcher = Spectator::Matchers::StartWithMatcher.new(start)
-          matcher.match?(partial).should be_false
+              match_data = matcher.match(partial)
+              match_data.matched?.should be_false
             end
           end
 
@@ -39,7 +44,8 @@ describe Spectator::Matchers::StartWithMatcher do
               start = 'f'
               partial = new_partial(value)
               matcher = Spectator::Matchers::StartWithMatcher.new(start)
-          matcher.match?(partial).should be_true
+              match_data = matcher.match(partial)
+              match_data.matched?.should be_true
             end
 
             context "not at start" do
@@ -48,7 +54,8 @@ describe Spectator::Matchers::StartWithMatcher do
                 start = 'b'
                 partial = new_partial(value)
                 matcher = Spectator::Matchers::StartWithMatcher.new(start)
-            matcher.match?(partial).should be_false
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_false
               end
             end
           end
@@ -59,7 +66,8 @@ describe Spectator::Matchers::StartWithMatcher do
               start = 'z'
               partial = new_partial(value)
               matcher = Spectator::Matchers::StartWithMatcher.new(start)
-          matcher.match?(partial).should be_false
+              match_data = matcher.match(partial)
+              match_data.matched?.should be_false
             end
           end
 
@@ -69,7 +77,8 @@ describe Spectator::Matchers::StartWithMatcher do
               start = /foo/i
               partial = new_partial(value)
               matcher = Spectator::Matchers::StartWithMatcher.new(start)
-          matcher.match?(partial).should be_true
+              match_data = matcher.match(partial)
+              match_data.matched?.should be_true
             end
 
             context "not at start" do
@@ -78,7 +87,8 @@ describe Spectator::Matchers::StartWithMatcher do
                 start = /bar/i
                 partial = new_partial(value)
                 matcher = Spectator::Matchers::StartWithMatcher.new(start)
-            matcher.match?(partial).should be_false
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_false
               end
             end
           end
@@ -89,7 +99,8 @@ describe Spectator::Matchers::StartWithMatcher do
               start = /baz/i
               partial = new_partial(value)
               matcher = Spectator::Matchers::StartWithMatcher.new(start)
-          matcher.match?(partial).should be_false
+              match_data = matcher.match(partial)
+              match_data.matched?.should be_false
             end
           end
         end
@@ -101,7 +112,8 @@ describe Spectator::Matchers::StartWithMatcher do
               start = :a
               partial = new_partial(array)
               matcher = Spectator::Matchers::StartWithMatcher.new(start)
-          matcher.match?(partial).should be_true
+              match_data = matcher.match(partial)
+              match_data.matched?.should be_true
             end
 
             context "not at start" do
@@ -110,7 +122,8 @@ describe Spectator::Matchers::StartWithMatcher do
                 start = :b
                 partial = new_partial(array)
                 matcher = Spectator::Matchers::StartWithMatcher.new(start)
-            matcher.match?(partial).should be_false
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_false
               end
             end
           end
@@ -121,7 +134,8 @@ describe Spectator::Matchers::StartWithMatcher do
               start = :z
               partial = new_partial(array)
               matcher = Spectator::Matchers::StartWithMatcher.new(start)
-          matcher.match?(partial).should be_false
+              match_data = matcher.match(partial)
+              match_data.matched?.should be_false
             end
           end
 
@@ -130,7 +144,8 @@ describe Spectator::Matchers::StartWithMatcher do
               array = %i[a b c]
               partial = new_partial(array)
               matcher = Spectator::Matchers::StartWithMatcher.new(Symbol)
-          matcher.match?(partial).should be_true
+              match_data = matcher.match(partial)
+              match_data.matched?.should be_true
             end
 
             context "not at start" do
@@ -138,7 +153,8 @@ describe Spectator::Matchers::StartWithMatcher do
                 array = [1, 2, 3, :a, :b, :c]
                 partial = new_partial(array)
                 matcher = Spectator::Matchers::StartWithMatcher.new(Symbol)
-            matcher.match?(partial).should be_false
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_false
               end
             end
           end
@@ -148,7 +164,8 @@ describe Spectator::Matchers::StartWithMatcher do
               array = %i[a b c]
               partial = new_partial(array)
               matcher = Spectator::Matchers::StartWithMatcher.new(Int32)
-          matcher.match?(partial).should be_false
+              match_data = matcher.match(partial)
+              match_data.matched?.should be_false
             end
           end
 
@@ -158,7 +175,8 @@ describe Spectator::Matchers::StartWithMatcher do
               start = /foo/i
               partial = new_partial(array)
               matcher = Spectator::Matchers::StartWithMatcher.new(start)
-          matcher.match?(partial).should be_true
+              match_data = matcher.match(partial)
+              match_data.matched?.should be_true
             end
 
             context "not at start" do
@@ -167,7 +185,8 @@ describe Spectator::Matchers::StartWithMatcher do
                 start = /bar/i
                 partial = new_partial(array)
                 matcher = Spectator::Matchers::StartWithMatcher.new(start)
-            matcher.match?(partial).should be_false
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_false
               end
             end
           end
@@ -178,7 +197,69 @@ describe Spectator::Matchers::StartWithMatcher do
               start = /qux/i
               partial = new_partial(array)
               matcher = Spectator::Matchers::StartWithMatcher.new(start)
-          matcher.match?(partial).should be_false
+              match_data = matcher.match(partial)
+              match_data.matched?.should be_false
+            end
+          end
+        end
+      end
+
+      describe "#values" do
+        context "with a String" do
+          context "expected" do
+            it "is the expected value" do
+              value = "FOOBAR"
+              first = /baz/i
+              partial = new_partial(value)
+              matcher = Spectator::Matchers::StartWithMatcher.new(first)
+              match_data = matcher.match(partial)
+              match_data.values[:expected].should eq(first)
+            end
+          end
+
+          context "actual" do
+            it "is the actual value" do
+              value = "FOOBAR"
+              first = /baz/i
+              partial = new_partial(value)
+              matcher = Spectator::Matchers::StartWithMatcher.new(first)
+              match_data = matcher.match(partial)
+              match_data.values[:actual].should eq(value)
+            end
+          end
+        end
+
+        context "with an Indexable" do
+          context "expected" do
+            it "is the expected value" do
+              array = %w[FOO BAR BAZ]
+              first = /qux/i
+              partial = new_partial(array)
+              matcher = Spectator::Matchers::StartWithMatcher.new(first)
+              match_data = matcher.match(partial)
+              match_data.values[:expected].should eq(first)
+            end
+          end
+
+          context "actual" do
+            it "is the first element" do
+              array = %w[FOO BAR BAZ]
+              first = /qux/i
+              partial = new_partial(array)
+              matcher = Spectator::Matchers::StartWithMatcher.new(first)
+              match_data = matcher.match(partial)
+              match_data.values[:actual].should eq(array.first)
+            end
+          end
+
+          context "list" do
+            it "is the full actual list" do
+              array = %w[FOO BAR BAZ]
+              first = /qux/i
+              partial = new_partial(array)
+              matcher = Spectator::Matchers::StartWithMatcher.new(first)
+              match_data = matcher.match(partial)
+              match_data.values[:list].should eq(array)
             end
           end
         end
@@ -191,7 +272,8 @@ describe Spectator::Matchers::StartWithMatcher do
             start = "baz"
             partial = new_partial(value)
             matcher = Spectator::Matchers::StartWithMatcher.new(start)
-        matcher.message(partial).should contain("#starts_with?")
+            match_data = matcher.match(partial)
+            match_data.message.should contain("#starts_with?")
           end
         end
 
@@ -200,14 +282,16 @@ describe Spectator::Matchers::StartWithMatcher do
             array = %i[a b c]
             partial = new_partial(array)
             matcher = Spectator::Matchers::StartWithMatcher.new(array.first)
-        matcher.message(partial).should contain("===")
+            match_data = matcher.match(partial)
+            match_data.message.should contain("===")
           end
 
           it "mentions first" do
             array = %i[a b c]
             partial = new_partial(array)
             matcher = Spectator::Matchers::StartWithMatcher.new(array.first)
-        matcher.message(partial).should contain("first")
+            match_data = matcher.match(partial)
+            match_data.message.should contain("first")
           end
         end
 
@@ -217,7 +301,8 @@ describe Spectator::Matchers::StartWithMatcher do
           label = "everything"
           partial = new_partial(value, label)
           matcher = Spectator::Matchers::StartWithMatcher.new(start)
-      matcher.message(partial).should contain(label)
+          match_data = matcher.match(partial)
+          match_data.message.should contain(label)
         end
 
         it "contains the expected label" do
@@ -226,7 +311,8 @@ describe Spectator::Matchers::StartWithMatcher do
           label = "everything"
           partial = new_partial(value)
           matcher = Spectator::Matchers::StartWithMatcher.new(start, label)
-      matcher.message(partial).should contain(label)
+          match_data = matcher.match(partial)
+          match_data.message.should contain(label)
         end
 
         context "when expected label is omitted" do
@@ -235,7 +321,8 @@ describe Spectator::Matchers::StartWithMatcher do
             start = "baz"
             partial = new_partial(value)
             matcher = Spectator::Matchers::StartWithMatcher.new(start)
-        matcher.message(partial).should contain(start)
+            match_data = matcher.match(partial)
+            match_data.message.should contain(start)
           end
         end
       end
@@ -247,7 +334,8 @@ describe Spectator::Matchers::StartWithMatcher do
             start = "baz"
             partial = new_partial(value)
             matcher = Spectator::Matchers::StartWithMatcher.new(start)
-        matcher.negated_message(partial).should contain("#starts_with?")
+            match_data = matcher.match(partial)
+            match_data.negated_message.should contain("#starts_with?")
           end
         end
 
@@ -256,14 +344,16 @@ describe Spectator::Matchers::StartWithMatcher do
             array = %i[a b c]
             partial = new_partial(array)
             matcher = Spectator::Matchers::StartWithMatcher.new(array.first)
-        matcher.negated_message(partial).should contain("===")
+            match_data = matcher.match(partial)
+            match_data.negated_message.should contain("===")
           end
 
           it "mentions first" do
             array = %i[a b c]
             partial = new_partial(array)
             matcher = Spectator::Matchers::StartWithMatcher.new(array.first)
-        matcher.negated_message(partial).should contain("first")
+            match_data = matcher.match(partial)
+            match_data.negated_message.should contain("first")
           end
         end
 
@@ -273,7 +363,8 @@ describe Spectator::Matchers::StartWithMatcher do
           label = "everything"
           partial = new_partial(value, label)
           matcher = Spectator::Matchers::StartWithMatcher.new(start)
-      matcher.negated_message(partial).should contain(label)
+          match_data = matcher.match(partial)
+          match_data.negated_message.should contain(label)
         end
 
         it "contains the expected label" do
@@ -282,7 +373,8 @@ describe Spectator::Matchers::StartWithMatcher do
           label = "everything"
           partial = new_partial(value)
           matcher = Spectator::Matchers::StartWithMatcher.new(start, label)
-      matcher.negated_message(partial).should contain(label)
+          match_data = matcher.match(partial)
+          match_data.negated_message.should contain(label)
         end
 
         context "when expected label is omitted" do
@@ -291,7 +383,10 @@ describe Spectator::Matchers::StartWithMatcher do
             start = "baz"
             partial = new_partial(value)
             matcher = Spectator::Matchers::StartWithMatcher.new(start)
-        matcher.negated_message(partial).should contain(start)
+            match_data = matcher.match(partial)
+            match_data.negated_message.should contain(start)
+          end
+        end
       end
     end
   end

src/spectator/matchers/start_with_matcher.cr

@@ -6,72 +6,84 @@ module Spectator::Matchers
   # Otherwise, it is treated as an `Enumerable` and the `first` value is compared against.
   struct StartWithMatcher(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)
-      actual = partial.actual
-      compare_method(actual, &.eval(actual, expected))
+    private def match_starts_with?(actual)
+      actual.starts_with?(expected)
+    end
+
+    # Determines whether the matcher is satisfied with the value given to it.
+    private def match_first?(actual)
+      expected === actual
     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)
+      actual = values.actual
+      if actual.responds_to?(:starts_with?)
+        StartsWithMatchData.new(match_starts_with?(actual), values)
+      else
+        first = actual.first
+        FirstMatchData.new(match_first?(first), values, first)
+      end
+    end
+
+    # Match data specific to this matcher.
+    # This type is used when the actual value responds to `starts_with?`.
+    private struct StartsWithMatchData(ExpectedType, ActualType) < MatchData
+      # Creates the match data.
+      def initialize(matched, @values : ExpectedActual(ExpectedType, ActualType))
+        super(matched)
+      end
+
+      # Information about the match.
+      def values
+        {
+          expected: @values.expected,
+          actual:   @values.actual,
+        }
       end
 
       # Describes the condition that satisfies the matcher.
       # This is informational and displayed to the end-user.
-    def message(partial)
-      method_string = compare_method(partial.actual, &.to_s)
-      "Expected #{partial.label} to start with #{label} (using #{method_string})"
+      def message
+        "#{@values.actual_label} starts with #{@values.expected_label} (using #starts_with?)"
       end
 
       # Describes the condition that won't satsify the matcher.
       # This is informational and displayed to the end-user.
-    def negated_message(partial)
-      method_string = compare_method(partial.actual, &.to_s)
-      "Expected #{partial.label} to not start with #{label} (using #{method_string})"
-    end
-
-    # Returns the method that should be used for comparison.
-    # Call `eval(actual, expected)` on the returned value.
-    private macro compare_method(actual, &block)
-      # If the actual type defines `starts_with?`,
-      # then use that for the comparison.
-      # Otherwise, treat the actual type as an `Enumerable`,
-      # and retrieve the first value to compare with.
-      # FIXME: Is there a better way to do this?
-      if {{actual}}.responds_to?(:starts_with?)
-        {{block.args.first}} = StartsWithCompareMethod.new
-        {{block.body}}
-      else
-        {{block.args.first}} = EnumerableCompareMethod.new
-        {{block.body}}
+      def negated_message
+        "#{@values.actual_label} does not start with #{@values.expected_label} (using #starts_with?)"
       end
     end
 
-    # Comparison method for types that define the `starts_with?` method.
-    private struct StartsWithCompareMethod
-      # Evaluates the condition to determine whether the matcher is satisfied.
-      def eval(actual, expected)
-        actual.starts_with?(expected)
+    # Match data specific to this matcher.
+    # This type is used when the actual value does not respond to `ends_with?`.
+    private struct FirstMatchData(ExpectedType, ActualType, FirstType) < MatchData
+      # Creates the match data.
+      def initialize(matched, @values : ExpectedActual(ExpectedType, ActualType), @first : FirstType)
+        super(matched)
       end
 
-      # String representation for end-user output.
-      def to_s
-        "#starts_with?"
-      end
+      # Information about the match.
+      def values
+        {
+          expected: @values.expected,
+          actual:   @first,
+          list:     @values.actual,
+        }
       end
 
-    # Comparison method for `Enumerable` types.
-    private struct EnumerableCompareMethod
-      # Evaluates the condition to determine whether the matcher is satisfied.
-      def eval(actual, expected)
-        expected === actual.first
+      # Describes the condition that satisfies the matcher.
+      # This is informational and displayed to the end-user.
+      def message
+        "#{@values.actual_label} starts with #{@values.expected_label} (using expected === actual.first)"
       end
 
-      # String representation for end-user output.
-      def to_s
-        "expected === actual.first"
+      # Describes the condition that won't satsify the matcher.
+      # This is informational and displayed to the end-user.
+      def negated_message
+        "#{@values.actual_label} does not start with #{@values.expected_label} (using expected === actual.first)"
       end
     end
   end