Merge pull request #569 from amomchilov/new-AnchorNotDefined-error

Raise specific error when an anchor isn't defined

4 files changed, 43 insertions, 14 deletions

diff --git a/lib/psych/exception.rb b/lib/psych/exception.rb
index 04a9a90..d7469a4 100644
--- a/lib/psych/exception.rb
+++ b/lib/psych/exception.rb
@@ -13,6 +13,13 @@ module Psych
     end
   end
 
+  # Subclasses `BadAlias` for backwards compatibility
+  class AnchorNotDefined < BadAlias
+    def initialize anchor_name
+      super "An alias referenced an unknown anchor: #{anchor_name}"
+    end
+  end
+
   class DisallowedClass < Exception
     def initialize action, klass_name
       super "Tried to #{action} unspecified class: #{klass_name}"
diff --git a/lib/psych/visitors/to_ruby.rb b/lib/psych/visitors/to_ruby.rb
index 0bf5198..cce5daf 100644
--- a/lib/psych/visitors/to_ruby.rb
+++ b/lib/psych/visitors/to_ruby.rb
@@ -323,7 +323,7 @@ module Psych
       end
 
       def visit_Psych_Nodes_Alias o
-        @st.fetch(o.anchor) { raise BadAlias, "Unknown alias: #{o.anchor}" }
+        @st.fetch(o.anchor) { raise AnchorNotDefined, o.anchor }
       end
 
       private
diff --git a/test/psych/test_hash.rb b/test/psych/test_hash.rb
index 0efa211..31eba85 100644
--- a/test/psych/test_hash.rb
+++ b/test/psych/test_hash.rb
@@ -102,16 +102,38 @@ module Psych
     end
 
     def test_ref_append
-      hash = Psych.unsafe_load(<<-eoyml)
----
-foo: &foo
-  hello: world
-bar:
-  <<: *foo
-eoyml
+      hash = Psych.unsafe_load(<<~eoyml)
+        ---
+        foo: &foo
+          hello: world
+        bar:
+          <<: *foo
+      eoyml
       assert_equal({"foo"=>{"hello"=>"world"}, "bar"=>{"hello"=>"world"}}, hash)
     end
 
+    def test_anchor_reuse
+      hash = Psych.unsafe_load(<<~eoyml)
+        ---
+        foo: &foo
+          hello: world
+        bar: *foo
+      eoyml
+      assert_equal({"foo"=>{"hello"=>"world"}, "bar"=>{"hello"=>"world"}}, hash)
+      assert_same(hash.fetch("foo"), hash.fetch("bar"))
+    end
+
+    def test_raises_if_anchor_not_defined
+      assert_raise(Psych::AnchorNotDefined) do
+        Psych.unsafe_load(<<~eoyml)
+          ---
+          foo: &foo
+            hello: world
+          bar: *not_foo
+        eoyml
+      end
+    end
+
     def test_recursive_hash
       h = { }
       h["recursive_reference"] = h
@@ -135,11 +157,11 @@ eoyml
         pend "This Ruby implementation doesn't support string deduplication"
       end
 
-      hashes = Psych.load(<<-eoyml)
----
-- unique_identifier: 1
-- unique_identifier: 2
-eoyml
+      hashes = Psych.load(<<~eoyml)
+        ---
+        - unique_identifier: 1
+        - unique_identifier: 2
+      eoyml
 
       assert_same hashes[0].keys.first, hashes[1].keys.first
     end
diff --git a/test/psych/test_merge_keys.rb b/test/psych/test_merge_keys.rb
index 8d2fcea..2f55a1e 100644
--- a/test/psych/test_merge_keys.rb
+++ b/test/psych/test_merge_keys.rb
@@ -117,7 +117,7 @@ development:
 bar:
   << : *foo
       eoyml
-      exp = assert_raise(Psych::BadAlias) { Psych.load(yaml, aliases: true) }
+      exp = assert_raise(Psych::AnchorNotDefined) { Psych.load(yaml, aliases: true) }
       assert_match 'foo', exp.message
     end