# YAML Test Matrix

--- &test-G9HC
  Title: Invalid anchor in zero indented sequence
  Tags: [ anchor, error, sequence ]

YAML

---
seq:
&anchor
- a
- b

Expected Events

+STR
+DOC ---
+MAP
=VAL :seq

Expected JSON



cpp-yamlcpp-event

 invalid_incorrect
+STR
+DOC
+MAP
=VAL :seq
+SEQ &1
=VAL :a
=VAL :b
-SEQ
-MAP
-DOC
-STR

nim-nimyaml-event

 invalid_incorrect
+STR
+DOC ---
+MAP
=VAL :seq
=VAL :
+SEQ &anchor
=VAL :a
=VAL :b
-SEQ
=VAL :
-MAP
-DOC
-STR

c-libfyaml-event

 invalid_correct
stdin:3:2: error: invalid anchor indent for sequence
&anchor
 ^~~~~~
+STR
+DOC ---
+MAP
=VAL :seq

c-libfyaml-json

 invalid_correct
stdin:3:2: error: invalid anchor indent for sequence
&anchor
 ^~~~~~

c-libyaml-event

 invalid_correct
Parse error: could not find expected ':'
+STR
+DOC ---
+MAP
=VAL :seq

dotnet-yamldotnet-event

 invalid_correct
Unhandled exception. YamlDotNet.Core.SyntaxErrorException: (Line: 4, Col: 1, Idx: 17) - (Line: 4, Col: 1, Idx: 17): While scanning a simple key, could not find expected ':'.
   at YamlDotNet.Core.Scanner.StaleSimpleKeys()
   at YamlDotNet.Core.Scanner.FetchNextToken()
   at YamlDotNet.Core.Scanner.FetchMoreTokens()
   at YamlDotNet.Core.Scanner.MoveNextWithoutConsuming()
   at YamlDotNet.Core.Parser.GetCurrentToken()
   at YamlDotNet.Core.Parser.ParseBlockMappingValue()
   at YamlDotNet.Core.Parser.StateMachine()
   at YamlDotNet.Core.Parser.MoveNext()
   at Program.ConvertToLibYamlStyleAnnotatedEventStream(TextReader textReader, TextWriter textWriter)
   at Program.Main(String[] commandLineArguments)
Aborted (core dumped)
+STR
+DOC ---
+MAP
=VAL :seq

dotnet-yamldotnet-json

 invalid_correct
Unhandled exception. YamlDotNet.Core.SyntaxErrorException: (Line: 4, Col: 1, Idx: 17) - (Line: 4, Col: 1, Idx: 17): While scanning a simple key, could not find expected ':'.
   at YamlDotNet.Core.Scanner.StaleSimpleKeys()
   at YamlDotNet.Core.Scanner.FetchNextToken()
   at YamlDotNet.Core.Scanner.FetchMoreTokens()
   at YamlDotNet.Core.Scanner.MoveNextWithoutConsuming()
   at YamlDotNet.Core.Parser.GetCurrentToken()
   at YamlDotNet.Core.Parser.ParseBlockMappingValue()
   at YamlDotNet.Core.Parser.StateMachine()
   at YamlDotNet.Core.Parser.MoveNext()
   at YamlDotNet.Core.ParserExtensions.Allow[T](IParser parser)
   at YamlDotNet.Serialization.NodeDeserializers.ScalarNodeDeserializer.YamlDotNet.Serialization.INodeDeserializer.Deserialize(IParser parser, Type expectedType, Func`3 nestedObjectDeserializer, Object& value)
   at YamlDotNet.Serialization.ValueDeserializers.NodeValueDeserializer.DeserializeValue(IParser parser, Type expectedType, SerializerState state, IValueDeserializer nestedObjectDeserializer)
   at YamlDotNet.Serialization.ValueDeserializers.AliasValueDeserializer.DeserializeValue(IParser parser, Type expectedType, SerializerState state, IValueDeserializer nestedObjectDeserializer)
   at YamlDotNet.Serialization.ValueDeserializers.NodeValueDeserializer.<>c__DisplayClass3_0.<DeserializeValue>b__0(IParser r, Type t)
   at YamlDotNet.Serialization.NodeDeserializers.DictionaryNodeDeserializer.DeserializeHelper(Type tKey, Type tValue, IParser parser, Func`3 nestedObjectDeserializer, IDictionary result)
   at YamlDotNet.Serialization.NodeDeserializers.DictionaryNodeDeserializer.YamlDotNet.Serialization.INodeDeserializer.Deserialize(IParser parser, Type expectedType, Func`3 nestedObjectDeserializer, Object& value)
   at YamlDotNet.Serialization.ValueDeserializers.NodeValueDeserializer.DeserializeValue(IParser parser, Type expectedType, SerializerState state, IValueDeserializer nestedObjectDeserializer)
   at YamlDotNet.Serialization.ValueDeserializers.AliasValueDeserializer.DeserializeValue(IParser parser, Type expectedType, SerializerState state, IValueDeserializer nestedObjectDeserializer)
   at YamlDotNet.Serialization.Deserializer.Deserialize(IParser parser, Type type)
   at YamlDotNet.Serialization.Deserializer.Deserialize(TextReader input, Type type)
   at YamlDotNet.Serialization.Deserializer.Deserialize(TextReader input)
   at Program.Main(String[] commandLineArguments)
Aborted (core dumped)

hs-hsyaml-event

 invalid_correct
Parsing error near byte offset Pos {posByteOffset = 9, posCharOffset = 9, posLine = 3, posColumn = 0} (Unexpected '&')
+STR
+DOC ---
+MAP
=VAL :seq
=VAL :
-MAP
-DOC

hs-hsyaml-json

 invalid_correct
hsyaml-parser: user error (Unexpected '&')

java-snakeyaml-event

 invalid_correct
Exception in thread "main" while scanning a simple key
 in 'reader', line 3, column 1:
    &anchor
    ^
could not find expected ':'
 in 'reader', line 4, column 1:
    - a
    ^

	at org.yaml.snakeyaml.scanner.ScannerImpl.stalePossibleSimpleKeys(ScannerImpl.java:464)
	at org.yaml.snakeyaml.scanner.ScannerImpl.fetchMoreTokens(ScannerImpl.java:289)
	at org.yaml.snakeyaml.scanner.ScannerImpl.checkToken(ScannerImpl.java:227)
	at org.yaml.snakeyaml.parser.ParserImpl$ParseBlockMappingValue.produce(ParserImpl.java:586)
	at org.yaml.snakeyaml.parser.ParserImpl.peekEvent(ParserImpl.java:158)
	at org.yaml.snakeyaml.Yaml$3.hasNext(Yaml.java:654)
	at org.yaml.editor.Snake2Events.yamlToEvents(Snake2Events.java:111)
	at org.yaml.editor.Snake2Events.main(Snake2Events.java:119)

java-snakeyaml-json

 invalid_correct
Exception in thread "main" while scanning a simple key
 in 'reader', line 3, column 1:
    &anchor
    ^
could not find expected ':'
 in 'reader', line 4, column 1:
    - a
    ^

	at org.yaml.snakeyaml.scanner.ScannerImpl.stalePossibleSimpleKeys(ScannerImpl.java:464)
	at org.yaml.snakeyaml.scanner.ScannerImpl.fetchMoreTokens(ScannerImpl.java:289)
	at org.yaml.snakeyaml.scanner.ScannerImpl.checkToken(ScannerImpl.java:227)
	at org.yaml.snakeyaml.parser.ParserImpl$ParseBlockMappingValue.produce(ParserImpl.java:586)
	at org.yaml.snakeyaml.parser.ParserImpl.peekEvent(ParserImpl.java:158)
	at org.yaml.snakeyaml.parser.ParserImpl.checkEvent(ParserImpl.java:148)
	at org.yaml.snakeyaml.composer.Composer.composeNode(Composer.java:136)
	at org.yaml.snakeyaml.composer.Composer.composeValueNode(Composer.java:257)
	at org.yaml.snakeyaml.composer.Composer.composeMappingChildren(Composer.java:248)
	at org.yaml.snakeyaml.composer.Composer.composeMappingNode(Composer.java:236)
	at org.yaml.snakeyaml.composer.Composer.composeNode(Composer.java:162)
	at org.yaml.snakeyaml.composer.Composer.getNode(Composer.java:95)
	at org.yaml.snakeyaml.constructor.BaseConstructor.getData(BaseConstructor.java:134)
	at org.yaml.snakeyaml.Yaml$1.next(Yaml.java:494)
	at org.yaml.editor.Snake2Json.yamlToJson(Snake2Json.java:18)
	at org.yaml.editor.Snake2Json.main(Snake2Json.java:25)

js-jsyaml-json

 invalid_correct
/node/node_modules/js-yaml/lib/js-yaml/loader.js:173
  throw generateError(state, message);
  ^
YAMLException: can not read a block mapping entry; a multiline key may not be an implicit key at line 4, column 1:
    - a
    ^
    at generateError (/node/node_modules/js-yaml/lib/js-yaml/loader.js:167:10)
    at throwError (/node/node_modules/js-yaml/lib/js-yaml/loader.js:173:9)
    at readBlockMapping (/node/node_modules/js-yaml/lib/js-yaml/loader.js:1073:9)
    at composeNode (/node/node_modules/js-yaml/lib/js-yaml/loader.js:1359:12)
    at readDocument (/node/node_modules/js-yaml/lib/js-yaml/loader.js:1519:3)
    at loadDocuments (/node/node_modules/js-yaml/lib/js-yaml/loader.js:1575:5)
    at Object.loadAll (/node/node_modules/js-yaml/lib/js-yaml/loader.js:1583:19)
    at Object.<anonymous> (/yaml/bin/js-jsyaml-json:7:13)
    at Module._compile (internal/modules/cjs/loader.js:778:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)

js-yaml-event

 invalid_correct
A collection cannot be both a mapping and a sequence
+STR
+DOC ---

js-yaml-json

 invalid_correct
/yaml/bin/js-yaml-json:8
  if (doc.errors.length !== 0) throw doc.errors[0]
                               ^

YAMLSyntaxError: A collection cannot be both a mapping and a sequence
    at Collection.parse (/node/node_modules/yaml/dist/parse-cst.js:346:24)
    at ParseContext.PlainValue._defineProperty (/node/node_modules/yaml/dist/parse-cst.js:1605:29)
    at Document.parseContents (/node/node_modules/yaml/dist/parse-cst.js:622:26)
    at Document.parse (/node/node_modules/yaml/dist/parse-cst.js:685:19)
    at Object.parse (/node/node_modules/yaml/dist/parse-cst.js:1723:18)
    at Object.parseAllDocuments (/node/node_modules/yaml/dist/index.js:32:33)
    at Object.<anonymous> (/yaml/bin/js-yaml-json:7:19)
    at Module._compile (internal/modules/cjs/loader.js:778:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)
    at Module.load (internal/modules/cjs/loader.js:653:32)

lua-lyaml-json

 invalid_correct
luajit: 2:1: could not find expected ':'
stack traceback:
	[C]: in function 'error'
	/usr/local/share/lua/5.1/lyaml/init.lua:291: in function 'error'
	/usr/local/share/lua/5.1/lyaml/init.lua:310: in function 'parse'
	/usr/local/share/lua/5.1/lyaml/init.lua:428: in function 'load_node'
	/usr/local/share/lua/5.1/lyaml/init.lua:363: in function 'load_node'
	/usr/local/share/lua/5.1/lyaml/init.lua:482: in function 'load'
	/yaml/bin/lua-lyaml-json:6: in main chunk
	[C]: at 0x55b6df07ef97

perl-pp-event

 invalid_correct
Line      : 3
Column    : 8
Expected  : WS
Got       : EOL
Where     : /perl5/lib/perl5/YAML/PP/Parser.pm line 386
YAML      : ""
  at /yaml/bin/perl-pp-event line 25.
+STR
+DOC ---
+MAP
=VAL :seq
=VAL :

perl-pp-json

 invalid_correct
Line      : 3
Column    : 8
Expected  : WS
Got       : EOL
Where     : /perl5/lib/perl5/YAML/PP/Parser.pm line 386
YAML      : ""
  at /perl5/lib/perl5/YAML/PP/Loader.pm line 92.

perl-pp-perl

 invalid_correct
Line      : 3
Column    : 8
Expected  : WS
Got       : EOL
Where     : /perl5/lib/perl5/YAML/PP/Parser.pm line 386
YAML      : ""
  at /perl5/lib/perl5/YAML/PP/Loader.pm line 92.

perl-pplibyaml-event

 invalid_correct
YAML::PP::LibYAML Error: The problem:

    could not find expected ':'

was found at , line: 4, column: 1
while scanning a simple key at line: 3, column: 1

perl-pplibyaml-json

 invalid_correct
YAML::PP::LibYAML Error: The problem:

    could not find expected ':'

was found at , line: 4, column: 1
while scanning a simple key at line: 3, column: 1

perl-pplibyaml-perl

 invalid_correct
YAML::PP::LibYAML Error: The problem:

    could not find expected ':'

was found at , line: 4, column: 1
while scanning a simple key at line: 3, column: 1

perl-syck-json

 invalid_correct
Syck parser (line 4, column 0): syntax error at /perl5/lib/perl5/x86_64-linux-thread-multi/YAML/Syck.pm line 60, <> line 1.

perl-syck-perl

 invalid_correct
Syck parser (line 4, column 0): syntax error at /perl5/lib/perl5/x86_64-linux-thread-multi/YAML/Syck.pm line 60, <> line 1.

perl-tiny-json

 invalid_correct
YAML::Tiny failed to classify line '&anchor' at /yaml/bin/perl-tiny-json line 12.

perl-tiny-perl

 invalid_correct
YAML::Tiny failed to classify line '&anchor' at /yaml/bin/perl-tiny-perl line 15.

perl-xs-json

 invalid_correct
YAML::XS::Load Error: The problem:

    could not find expected ':'

was found at document: 1, line: 4, column: 1
while scanning a simple key at line: 3, column: 1

perl-xs-perl

 invalid_correct
YAML::XS::Load Error: The problem:

    could not find expected ':'

was found at document: 1, line: 4, column: 1
while scanning a simple key at line: 3, column: 1

perl-yaml-json

 invalid_correct
YAML Error: Invalid element in map
   Code: YAML_LOAD_ERR_BAD_MAP_ELEMENT
   Line: 3
   Document: 1
 at /perl5/lib/perl5/YAML/Loader.pm line 360.

perl-yaml-perl

 invalid_correct
YAML Error: Invalid element in map
   Code: YAML_LOAD_ERR_BAD_MAP_ELEMENT
   Line: 3
   Document: 1
 at /perl5/lib/perl5/YAML/Loader.pm line 360.

py-pyyaml-event

 invalid_correct
Traceback (most recent call last):
  File "/yaml/bin/py-pyyaml-event", line 7, in <module>
    for event in yaml.parse(sys.stdin.read()):
  File "/python/lib/python3.7/site-packages/yaml/__init__.py", line 75, in parse
    while loader.check_event():
  File "/python/lib/python3.7/site-packages/yaml/parser.py", line 98, in check_event
    self.current_event = self.state()
  File "/python/lib/python3.7/site-packages/yaml/parser.py", line 449, in parse_block_mapping_value
    if not self.check_token(KeyToken, ValueToken, BlockEndToken):
  File "/python/lib/python3.7/site-packages/yaml/scanner.py", line 116, in check_token
    self.fetch_more_tokens()
  File "/python/lib/python3.7/site-packages/yaml/scanner.py", line 162, in fetch_more_tokens
    self.stale_possible_simple_keys()
  File "/python/lib/python3.7/site-packages/yaml/scanner.py", line 292, in stale_possible_simple_keys
    "could not find expected ':'", self.get_mark())
yaml.scanner.ScannerError: while scanning a simple key
  in "<unicode string>", line 3, column 1:
    &anchor
    ^
could not find expected ':'
  in "<unicode string>", line 4, column 1:
    - a
    ^
+STR
+DOC ---
+MAP
=VAL :seq

py-pyyaml-json

 invalid_correct
Traceback (most recent call last):
  File "/yaml/bin/py-pyyaml-json", line 19, in <module>
    for doc in yaml.load_all(sys.stdin.read(), Loader=yaml.FullLoader):
  File "/python/lib/python3.7/site-packages/yaml/__init__.py", line 130, in load_all
    yield loader.get_data()
  File "/python/lib/python3.7/site-packages/yaml/constructor.py", line 45, in get_data
    return self.construct_document(self.get_node())
  File "/python/lib/python3.7/site-packages/yaml/composer.py", line 27, in get_node
    return self.compose_document()
  File "/python/lib/python3.7/site-packages/yaml/composer.py", line 55, in compose_document
    node = self.compose_node(None, None)
  File "/python/lib/python3.7/site-packages/yaml/composer.py", line 84, in compose_node
    node = self.compose_mapping_node(anchor)
  File "/python/lib/python3.7/site-packages/yaml/composer.py", line 133, in compose_mapping_node
    item_value = self.compose_node(node, item_key)
  File "/python/lib/python3.7/site-packages/yaml/composer.py", line 64, in compose_node
    if self.check_event(AliasEvent):
  File "/python/lib/python3.7/site-packages/yaml/parser.py", line 98, in check_event
    self.current_event = self.state()
  File "/python/lib/python3.7/site-packages/yaml/parser.py", line 449, in parse_block_mapping_value
    if not self.check_token(KeyToken, ValueToken, BlockEndToken):
  File "/python/lib/python3.7/site-packages/yaml/scanner.py", line 116, in check_token
    self.fetch_more_tokens()
  File "/python/lib/python3.7/site-packages/yaml/scanner.py", line 162, in fetch_more_tokens
    self.stale_possible_simple_keys()
  File "/python/lib/python3.7/site-packages/yaml/scanner.py", line 292, in stale_possible_simple_keys
    "could not find expected ':'", self.get_mark())
yaml.scanner.ScannerError: while scanning a simple key
  in "<unicode string>", line 3, column 1:
    &anchor
    ^
could not find expected ':'
  in "<unicode string>", line 4, column 1:
    - a
    ^

py-pyyaml-py

 invalid_correct
Traceback (most recent call last):
  File "/yaml/bin/py-pyyaml-py", line 36, in <module>
    for doc in yaml.load_all(sys.stdin.read(), Loader=yaml.FullLoader):
  File "/python/lib/python3.7/site-packages/yaml/__init__.py", line 130, in load_all
    yield loader.get_data()
  File "/python/lib/python3.7/site-packages/yaml/constructor.py", line 45, in get_data
    return self.construct_document(self.get_node())
  File "/python/lib/python3.7/site-packages/yaml/composer.py", line 27, in get_node
    return self.compose_document()
  File "/python/lib/python3.7/site-packages/yaml/composer.py", line 55, in compose_document
    node = self.compose_node(None, None)
  File "/python/lib/python3.7/site-packages/yaml/composer.py", line 84, in compose_node
    node = self.compose_mapping_node(anchor)
  File "/python/lib/python3.7/site-packages/yaml/composer.py", line 133, in compose_mapping_node
    item_value = self.compose_node(node, item_key)
  File "/python/lib/python3.7/site-packages/yaml/composer.py", line 64, in compose_node
    if self.check_event(AliasEvent):
  File "/python/lib/python3.7/site-packages/yaml/parser.py", line 98, in check_event
    self.current_event = self.state()
  File "/python/lib/python3.7/site-packages/yaml/parser.py", line 449, in parse_block_mapping_value
    if not self.check_token(KeyToken, ValueToken, BlockEndToken):
  File "/python/lib/python3.7/site-packages/yaml/scanner.py", line 116, in check_token
    self.fetch_more_tokens()
  File "/python/lib/python3.7/site-packages/yaml/scanner.py", line 162, in fetch_more_tokens
    self.stale_possible_simple_keys()
  File "/python/lib/python3.7/site-packages/yaml/scanner.py", line 292, in stale_possible_simple_keys
    "could not find expected ':'", self.get_mark())
yaml.scanner.ScannerError: while scanning a simple key
  in "<unicode string>", line 3, column 1:
    &anchor
    ^
could not find expected ':'
  in "<unicode string>", line 4, column 1:
    - a
    ^

py-ruamel-event

 invalid_correct
Traceback (most recent call last):
  File "/yaml/bin/py-ruamel-event", line 7, in <module>
    for event in ruamel.yaml.parse(sys.stdin.read()):
  File "/python/lib/python3.7/site-packages/ruamel/yaml/main.py", line 907, in parse
    while loader._parser.check_event():
  File "/python/lib/python3.7/site-packages/ruamel/yaml/parser.py", line 140, in check_event
    self.current_event = self.state()
  File "/python/lib/python3.7/site-packages/ruamel/yaml/parser.py", line 603, in parse_block_mapping_value
    if self.scanner.check_token(ValueToken):
  File "/python/lib/python3.7/site-packages/ruamel/yaml/scanner.py", line 170, in check_token
    self.fetch_more_tokens()
  File "/python/lib/python3.7/site-packages/ruamel/yaml/scanner.py", line 222, in fetch_more_tokens
    self.stale_possible_simple_keys()
  File "/python/lib/python3.7/site-packages/ruamel/yaml/scanner.py", line 359, in stale_possible_simple_keys
    self.reader.get_mark(),
ruamel.yaml.scanner.ScannerError: while scanning a simple key
  in "<unicode string>", line 3, column 1:
    &anchor
    ^ (line: 3)
could not find expected ':'
  in "<unicode string>", line 4, column 1:
    - a
    ^ (line: 4)
+STR
+DOC ---
+MAP
=VAL :seq

py-ruamel-json

 invalid_correct
Traceback (most recent call last):
  File "/yaml/bin/py-ruamel-json", line 19, in <module>
    for doc in ruamel.yaml.load_all(sys.stdin.read(), Loader=ruamel.yaml.Loader):
  File "/python/lib/python3.7/site-packages/ruamel/yaml/main.py", line 976, in load_all
    yield loader._constructor.get_data()
  File "/python/lib/python3.7/site-packages/ruamel/yaml/constructor.py", line 106, in get_data
    return self.construct_document(self.composer.get_node())
  File "/python/lib/python3.7/site-packages/ruamel/yaml/composer.py", line 68, in get_node
    return self.compose_document()
  File "/python/lib/python3.7/site-packages/ruamel/yaml/composer.py", line 101, in compose_document
    node = self.compose_node(None, None)
  File "/python/lib/python3.7/site-packages/ruamel/yaml/composer.py", line 138, in compose_node
    node = self.compose_mapping_node(anchor)
  File "/python/lib/python3.7/site-packages/ruamel/yaml/composer.py", line 218, in compose_mapping_node
    item_value = self.compose_node(node, item_key)
  File "/python/lib/python3.7/site-packages/ruamel/yaml/composer.py", line 111, in compose_node
    if self.parser.check_event(AliasEvent):
  File "/python/lib/python3.7/site-packages/ruamel/yaml/parser.py", line 140, in check_event
    self.current_event = self.state()
  File "/python/lib/python3.7/site-packages/ruamel/yaml/parser.py", line 603, in parse_block_mapping_value
    if self.scanner.check_token(ValueToken):
  File "/python/lib/python3.7/site-packages/ruamel/yaml/scanner.py", line 170, in check_token
    self.fetch_more_tokens()
  File "/python/lib/python3.7/site-packages/ruamel/yaml/scanner.py", line 222, in fetch_more_tokens
    self.stale_possible_simple_keys()
  File "/python/lib/python3.7/site-packages/ruamel/yaml/scanner.py", line 359, in stale_possible_simple_keys
    self.reader.get_mark(),
ruamel.yaml.scanner.ScannerError: while scanning a simple key
  in "<unicode string>", line 3, column 1:
    &anchor
    ^ (line: 3)
could not find expected ':'
  in "<unicode string>", line 4, column 1:
    - a
    ^ (line: 4)

py-ruamel-py

 invalid_correct
Traceback (most recent call last):
  File "/yaml/bin/py-ruamel-py", line 36, in <module>
    for doc in ruamel.yaml.load_all(sys.stdin.read(), Loader=ruamel.yaml.Loader):
  File "/python/lib/python3.7/site-packages/ruamel/yaml/main.py", line 976, in load_all
    yield loader._constructor.get_data()
  File "/python/lib/python3.7/site-packages/ruamel/yaml/constructor.py", line 106, in get_data
    return self.construct_document(self.composer.get_node())
  File "/python/lib/python3.7/site-packages/ruamel/yaml/composer.py", line 68, in get_node
    return self.compose_document()
  File "/python/lib/python3.7/site-packages/ruamel/yaml/composer.py", line 101, in compose_document
    node = self.compose_node(None, None)
  File "/python/lib/python3.7/site-packages/ruamel/yaml/composer.py", line 138, in compose_node
    node = self.compose_mapping_node(anchor)
  File "/python/lib/python3.7/site-packages/ruamel/yaml/composer.py", line 218, in compose_mapping_node
    item_value = self.compose_node(node, item_key)
  File "/python/lib/python3.7/site-packages/ruamel/yaml/composer.py", line 111, in compose_node
    if self.parser.check_event(AliasEvent):
  File "/python/lib/python3.7/site-packages/ruamel/yaml/parser.py", line 140, in check_event
    self.current_event = self.state()
  File "/python/lib/python3.7/site-packages/ruamel/yaml/parser.py", line 603, in parse_block_mapping_value
    if self.scanner.check_token(ValueToken):
  File "/python/lib/python3.7/site-packages/ruamel/yaml/scanner.py", line 170, in check_token
    self.fetch_more_tokens()
  File "/python/lib/python3.7/site-packages/ruamel/yaml/scanner.py", line 222, in fetch_more_tokens
    self.stale_possible_simple_keys()
  File "/python/lib/python3.7/site-packages/ruamel/yaml/scanner.py", line 359, in stale_possible_simple_keys
    self.reader.get_mark(),
ruamel.yaml.scanner.ScannerError: while scanning a simple key
  in "<unicode string>", line 3, column 1:
    &anchor
    ^ (line: 3)
could not find expected ':'
  in "<unicode string>", line 4, column 1:
    - a
    ^ (line: 4)

ruby-psych-json

 invalid_correct
/usr/lib/ruby/2.5.0/psych.rb:405:in `parse': (<unknown>): could not find expected ':' while scanning a simple key at line 3 column 1 (Psych::SyntaxError)
	from /usr/lib/ruby/2.5.0/psych.rb:405:in `parse_stream'
	from /usr/lib/ruby/2.5.0/psych.rb:488:in `load_stream'
	from /yaml/bin/ruby-psych-json:6:in `<main>'