Add diff! message to wire_protocol to allow clients to more easily sa…

…tisfy the 80% use case where you want to diff the table and fail the step if the diff fails.

History.txt

@@ -1,3 +1,8 @@
+== In Git
+
+=== New features
+* Add diff! message to wire protocol to allow for immediate diff response to invokes (Matt Wynne)
+
 == 0.6.2 2010-01-18
 
 === Bugfixes

features/wire_protocol_table_diffing.feature

@@ -90,3 +90,28 @@ Feature: Wire protocol table diffing
       1 step (1 failed)
 
       """
+
+  Scenario: Invoke a step definition which asks for an immediate diff that fails
+    Given there is a wire server running on port 54321 which understands the following protocol:
+      | request                                              | response                            |
+      | ["step_matches",{"name_to_match":"we're all wired"}] | ["success",[{"id":"1", "args":[]}]] |
+      | ["begin_scenario"]                                   | ["success"]                         |
+      | ["invoke",{"id":"1","args":[]}]                      | ["diff!",[[["a"]],[["b"]]]]         |
+      | ["end_scenario"]                                     | ["success"]                         |
+    When I run cucumber -f progress
+    And it should fail with
+      """
+      F
+
+      (::) failed steps (::)
+
+      Tables were not identical (Cucumber::Ast::Table::Different)
+      features/wired.feature:2:in `Given we're all wired'
+      
+      Failing Scenarios:
+      cucumber features/wired.feature:1 # Scenario: Wired
+
+      1 scenario (1 failed)
+      1 step (1 failed)
+
+      """

lib/cucumber/wire_support/wire_protocol/requests.rb

@@ -64,12 +64,16 @@ def execute(step_definition_id, args)
           def handle_pending(message)
             raise Pending, message || "TODO"
           end
-
-          def handle_diff(tables)
+          
+          def handle_diff!(tables)
             table1 = Ast::Table.new(tables[0])
             table2 = Ast::Table.new(tables[1])
+            table1.diff!(table2)
+          end
+
+          def handle_diff(tables)
             begin
-              table1.diff!(table2)
+              handle_diff!(tables)
             rescue Cucumber::Ast::Table::Different
               @connection.diff_failed
             end