Fix error formatting in debug mode

Backtrace filtering was only disabled for exception cause, this change
ensure no backtrace filtering at all in debug mode.

* Prevent main exception filtering when debug mode is enabled;
* Test when exception cause must be displayed;
* Test how exception cause must be displayed.

features/cli/debug.feature

@@ -1,11 +1,13 @@
 Feature: CLI debug option
 
-  Background:
-    Given a recipe with:
-      """
-      task(:trigger_error) { fail 'some error' }
-      """
-
-  Scenario: reports recipe errors
+  Scenario: reports recipe errors with their cause
+    Given a recipe with an error
     When I execute the recipe with option -d
     Then the output must match /\ARuntimeError:.*\n\ncause:\nRuntimeError:/
+
+  Scenario: does not exclude anything from backtrace
+    Given a recipe using a remote
+    When I execute the recipe on unknown remote target with option -d
+    Then the output must contain "producer-core"
+    And the output must contain "net-ssh"
+    And the output must contain ruby lib directory

features/steps/output_steps.rb

@@ -26,6 +26,10 @@ Then /^the error output must contain exactly "([^"]+)"$/ do |content|
   assert_exact_output content, all_stderr
 end
 
+Then /^the output must contain ruby lib directory$/ do
+  assert_partial_output RbConfig::CONFIG['rubylibdir'], all_output
+end
+
 Then /^the output must not contain ruby lib directory$/ do
   assert_no_partial_output RbConfig::CONFIG['rubylibdir'], all_output
 end

features/steps/recipe_steps.rb

@@ -27,6 +27,11 @@ When /^I execute the recipe on unknown remote target$/ do
   assert_matching_output '\ASocketError', all_output
 end
 
+When /^I execute the recipe on unknown remote target with option (-.+)$/ do |option|
+  run_simple "producer recipe.rb #{option} -t #unknown_host.test", false
+  assert_matching_output '\ASocketError', all_output
+end
+
 When /^I successfully execute the recipe$/ do
   step 'I execute the recipe'
   assert_exit_status 0

lib/producer/core/error_formatter.rb

@@ -18,7 +18,7 @@ module Producer
       end
 
       def format(exception)
-        lines = format_exception exception
+        lines = format_exception exception, filter: !debug?
 
         if debug? && exception.cause
           lines << ''

spec/producer/core/error_formatter_spec.rb

@@ -25,9 +25,10 @@ module Producer
       describe '#format' do
         let(:rubylibdir)  { RbConfig::CONFIG['rubylibdir'] }
         let(:bt)          { %W[backtrace /producer-core /net-ssh #{rubylibdir}] }
+        let(:exception)   { RuntimeError.new('some exception').tap { |o| o.set_backtrace bt } }
 
-        def exception
-          begin fail 'original exception' rescue fail 'some exception' end
+        def exception_with_cause
+          begin fail 'exception cause' rescue fail 'some exception' end
         rescue => e
           e.tap { |o| o.set_backtrace bt }
         end
@@ -41,7 +42,6 @@ module Producer
           expect(formatter.format exception).to match /^\s+backtrace$/
         end
 
-        context 'filtering' do
         it 'excludes producer code from the backtrace' do
           expect(formatter.format exception).not_to include 'producer-core'
         end
@@ -54,12 +54,30 @@ module Producer
           expect(formatter.format exception).not_to include rubylibdir
         end
 
+        context 'when exception has a cause' do
+          it 'does not include the cause' do
+            expect(formatter.format exception_with_cause)
+              .not_to include 'exception cause'
+          end
+        end
+
         context 'when debug is enabled' do
           let(:debug) { true }
 
-            it 'does not exclude producer code from the backtrace' do
+          it 'does not filter the backtrace' do
             expect(formatter.format exception).to include 'producer-core'
           end
+
+          context 'when exception has a cause' do
+            it 'includes the exception cause' do
+              expect(formatter.format exception_with_cause)
+                .to include 'exception cause'
+            end
+
+            it 'formats the cause' do
+              expect(formatter.format exception_with_cause)
+                .to match /^cause:\nRuntimeError: exception cause/
+            end
           end
         end
       end