Implement recipe error reporting feature

features/recipe.feature

@@ -9,6 +9,21 @@ Feature: recipe evaluation
     Then the exit status must be 0
     And the output must contain "hello from recipe"
 
+  Scenario: reports errors when evaluating an invalid recipe
+    Given a recipe with:
+      """
+      puts 'OK'
+
+      invalid_keyword
+      """
+    When I execute the recipe
+    Then the exit status must be 70
+    And the output must match:
+      """
+      \AOK
+      recipe.rb:3:.+invalid recipe keyword `invalid_keyword'
+      """
+
   Scenario: source keyword, requires a recipe file
     Given a recipe with:
       """