Improve CLI error reporting

features/cli_error_reporting.feature

@@ -0,0 +1,20 @@
+Feature: CLI error reporting
+
+  Background:
+    Given a recipe with:
+      """
+      task(:trigger_error) { fail 'some error' }
+      """
+
+  Scenario: reports recipe errors
+    When I execute the recipe
+    Then the exit status must be 70
+    And the output must match /\ARuntimeError: some error\n/
+
+  Scenario: reports errors with a backtrace
+    When I execute the recipe
+    Then the output must match /^\s+recipe\.rb:\d+:in /
+
+  Scenario: prepends recipe file path in the backtrace
+    When I execute the recipe
+    Then the output must match /^\s+recipe\.rb \(recipe\)\n\s+recipe\.rb:/