preserve directives, optional push root level scalar to own line

You need to set YAML().scalar_after_indicator = False to get a single scalar document
starting on its own line (instead of after the directives end indicator: --- abc")

fixes issue #304

*When this change indeed resolves your problem, please **Close** this issue*.
*(You can do so using the WorkFlow pull-down (close to the top right of this page))*

2 files changed, 60 insertions, 0 deletions

diff --git a/_test/roundtrip.py b/_test/roundtrip.py
index ee430a3..090b9e0 100644
--- a/_test/roundtrip.py
+++ b/_test/roundtrip.py
@@ -151,6 +151,55 @@ def round_trip(
     return data
 
 
+def na_round_trip(
+    inp,
+    outp=None,
+    extra=None,
+    intermediate=None,
+    indent=None,
+    top_level_colon_align=None,
+    prefix_colon=None,
+    preserve_quotes=None,
+    explicit_start=None,
+    explicit_end=None,
+    version=None,
+    dump_data=None,
+):
+    """
+    inp:    input string to parse
+    outp:   expected output (equals input if not specified)
+    """
+    if outp is None:
+        outp = inp
+    if version is not None:
+        version = version
+    doutp = dedent(outp)
+    if extra is not None:
+        doutp += extra
+    yaml = YAML()
+    yaml.preserve_quotes = preserve_quotes
+    yaml.scalar_after_indicator = False  # newline after every directives end
+    data = yaml.load(inp)
+    if dump_data:
+        print('data', data)
+    if intermediate is not None:
+        if isinstance(intermediate, dict):
+            for k, v in intermediate.items():
+                if data[k] != v:
+                    print('{0!r} <> {1!r}'.format(data[k], v))
+                    raise ValueError
+    yaml.indent = indent
+    yaml.top_level_colon_align = top_level_colon_align
+    yaml.prefix_colon = prefix_colon
+    yaml.explicit_start = explicit_start
+    yaml.explicit_end = explicit_end
+    res = yaml.dump(data, compare=doutp)
+    #if res != doutp:
+    #    diff(doutp, res, 'input string')
+    #print('\nroundtrip data:\n', res, sep="")
+    #assert res == doutp
+
+
 def YAML(**kw):
     import ruamel.yaml  # NOQA
 
diff --git a/_test/test_issues.py b/_test/test_issues.py
index 3692f61..9b301a9 100644
--- a/_test/test_issues.py
+++ b/_test/test_issues.py
@@ -8,6 +8,7 @@ import pytest  # NOQA
 
 from roundtrip import (
     round_trip,
+    na_round_trip,
     round_trip_load,
     round_trip_dump,
     dedent,
@@ -850,6 +851,16 @@ class TestIssues:
                            match='while scanning a directive'):
             yaml.load(inp)
 
+    def test_issue_304(self):
+        inp = """
+	%YAML 1.2
+	%TAG ! tag:example.com,2019:
+	---
+	!foo null
+	...
+        """
+        d = na_round_trip(inp)  # NOQA
+
 #    @pytest.mark.xfail(strict=True, reason='bla bla', raises=AssertionError)
 #    def test_issue_ xxx(self):
 #        inp = """