Provide better failure messages for include_json matcher. Addresses issue #45

Author: DanOlson

lib/json_spec/matchers/include_json.rb

@@ -5,13 +5,17 @@ class IncludeJson
       include JsonSpec::Exclusion
       include JsonSpec::Messages
 
+      attr_reader :actual_json
+
       def initialize(expected_json = nil)
         @expected_json = expected_json
       end
 
       def matches?(actual_json)
         raise "Expected included JSON not provided" if @expected_json.nil?
 
+        self.actual_json = actual_json
+
         actual = parse_json(actual_json, @path)
         expected = exclude_keys(parse_json(@expected_json))
         case actual
@@ -43,18 +47,24 @@ def including(*keys)
       end
 
       def failure_message
-        message_with_path("Expected included JSON")
+        message_with_path("Expected #{actual_json} to include #{@expected_json}")
       end
       alias :failure_message_for_should :failure_message
 
       def failure_message_when_negated
-        message_with_path("Expected excluded JSON")
+        message_with_path("Expected #{actual_json} to exclude #{@expected_json}")
       end
       alias :failure_message_for_should_not :failure_message_when_negated
 
       def description
         message_with_path("include JSON")
       end
+
+      private
+
+      def actual_json=(json)
+        @actual_json = json
+      end
     end
   end
 end

spec/json_spec/matchers/include_json_spec.rb

@@ -71,6 +71,22 @@
     matcher.description.should == %(include JSON at path "json/0")
   end
 
+  it "provides a useful failure message for should" do
+    actual   = %({"ids": [1,2,3]})
+    expected = %({"ids": [4,5,6]})
+    matcher  = include_json(expected)
+    matcher.matches?(actual)
+    matcher.failure_message_for_should.should == "Expected #{actual} to include #{expected}"
+  end
+
+  it "provides a useful failure message for should not" do
+    actual   = %({"ids": [1,2,3]})
+    expected = actual
+    matcher  = include_json(expected)
+    matcher.matches?(actual)
+    matcher.failure_message_for_should_not.should == "Expected #{actual} to exclude #{expected}"
+  end
+
   it "raises an error when not given expected JSON" do
     expect{ %([{"id":1,"two":3}]).should include_json }.to raise_error
   end