Merge pull request #382 from ruby/exception-handling-refactor

Exception backtraces should round trip

3 files changed, 36 insertions, 32 deletions

diff --git a/lib/psych/visitors/to_ruby.rb b/lib/psych/visitors/to_ruby.rb
index 74a52df..c265acb 100644
--- a/lib/psych/visitors/to_ruby.rb
+++ b/lib/psych/visitors/to_ruby.rb
@@ -252,6 +252,8 @@ module Psych
 
           e = build_exception((resolve_class($1) || class_loader.exception),
                               h.delete('message'))
+
+          e.set_backtrace h.delete('backtrace') if h.key? 'backtrace'
           init_with(e, h, o)
 
         when '!set', 'tag:yaml.org,2002:set'
diff --git a/lib/psych/visitors/yaml_tree.rb b/lib/psych/visitors/yaml_tree.rb
index cfed8f1..62d1d5c 100644
--- a/lib/psych/visitors/yaml_tree.rb
+++ b/lib/psych/visitors/yaml_tree.rb
@@ -181,41 +181,11 @@ module Psych
       end
 
       def visit_Exception o
-        tag = ['!ruby/exception', o.class.name].join ':'
-
-        @emitter.start_mapping nil, tag, false, Nodes::Mapping::BLOCK
-
-        {
-          'message'   => private_iv_get(o, 'mesg'),
-          'backtrace' => private_iv_get(o, 'backtrace'),
-        }.each do |k,v|
-          next unless v
-          @emitter.scalar k, nil, nil, true, false, Nodes::Scalar::ANY
-          accept v
-        end
-
-        dump_ivars o
-
-        @emitter.end_mapping
+        dump_exception o, private_iv_get(o, 'mesg')
       end
 
       def visit_NameError o
-        tag = ['!ruby/exception', o.class.name].join ':'
-
-        @emitter.start_mapping nil, tag, false, Nodes::Mapping::BLOCK
-
-        {
-          'message'   => o.message.to_s,
-          'backtrace' => private_iv_get(o, 'backtrace'),
-        }.each do |k,v|
-          next unless v
-          @emitter.scalar k, nil, nil, true, false, Nodes::Scalar::ANY
-          accept v
-        end
-
-        dump_ivars o
-
-        @emitter.end_mapping
+        dump_exception o, o.message.to_s
       end
 
       def visit_Regexp o
@@ -492,6 +462,24 @@ module Psych
       def dump_list o
       end
 
+      def dump_exception o, msg
+        tag = ['!ruby/exception', o.class.name].join ':'
+
+        @emitter.start_mapping nil, tag, false, Nodes::Mapping::BLOCK
+
+        if msg
+          @emitter.scalar 'message', nil, nil, true, false, Nodes::Scalar::ANY
+          accept msg
+        end
+
+        @emitter.scalar 'backtrace', nil, nil, true, false, Nodes::Scalar::ANY
+        accept o.backtrace
+
+        dump_ivars o
+
+        @emitter.end_mapping
+      end
+
       def format_time time
         if time.utc?
           time.strftime("%Y-%m-%d %H:%M:%S.%9N Z")
diff --git a/test/psych/test_exception.rb b/test/psych/test_exception.rb
index df7fd73..e7fc88c 100644
--- a/test/psych/test_exception.rb
+++ b/test/psych/test_exception.rb
@@ -23,6 +23,20 @@ module Psych
       $VERBOSE = @orig_verbose
     end
 
+    def make_ex msg = 'oh no!'
+      begin
+        raise msg
+      rescue ::Exception => e
+        e
+      end
+    end
+
+    def test_backtrace
+      err     = make_ex
+      new_err = Psych.load(Psych.dump(err))
+      assert_equal err.backtrace, new_err.backtrace
+    end
+
     def test_naming_exception
       err     = String.xxx rescue $!
       new_err = Psych.load(Psych.dump(err))