add initial (diff only) support for YAML streams

Author: mr-mixas

nested_diff/cli.py

@@ -621,7 +621,57 @@ def _default_constructor(loader, tag_suffix, node):  # noqa: ARG001
 
     def decode(self, data):
         """Parse YAML string."""
-        return self.yaml.load(data, Loader=self.yaml_loader, **self.opts)
+        items = list(
+            self.yaml.load_all(data, Loader=self.yaml_loader, **self.opts),
+        )
+
+        if len(items) == 1:
+            return items[0]
+
+        return ListOfDocuments(items)
+
+
+class ListOfDocuments:
+    """Wrapper to represent bunch of documents like YAML stream."""
+
+    def __init__(self, items):
+        """Initialize wrapper.
+
+        Args:
+            items: list of documents.
+
+        """
+        self.items = items
+
+    def __repr__(self):
+        """Repr for wrapper."""
+        return f'ListOfDocuments({self.items})'
+
+
+class ListOfDocumentsHandler(nested_diff.handlers.ListHandler):
+    """ListOfDocuments handler."""
+
+    extension_id = 'nested_diff.ListOfDocuments'
+    handled_type = ListOfDocuments
+
+    def diff(self, differ, a, b):
+        """Calculate diff for two ListOfDocuments objects.
+
+        Args:
+            differ: nested_diff.Differ object.
+            a: First object to diff.
+            b: Second object to diff.
+
+        Returns:
+            Tuple: equality flag and nested diff.
+
+        """
+        equal, diff = differ.diff(a.items, b.items)
+
+        if diff:
+            diff['E'] = self.extension_id
+
+        return equal, diff
 
 
 class YamlNode:

nested_diff/diff_tool.py

@@ -58,6 +58,7 @@ def diff(self, a, b, **kwargs):
             diff_opts['R'] = int(diff_opts['R'])
 
         differ = nested_diff.Differ(**diff_opts)
+        differ.set_handler(nested_diff.cli.ListOfDocumentsHandler())
         differ.set_handler(nested_diff.cli.YamlNodeHandler())
 
         if self.args.text_ctx >= 0:
@@ -289,6 +290,7 @@ def __init__(  # noqa: PLR0913
 
         fmt_class = self.get_formatter_class(base_class, values=values)
         self.encoder = fmt_class(**self.get_opts(kwargs))
+        self.encoder.set_handler(nested_diff.cli.ListOfDocumentsHandler())
         self.encoder.set_handler(nested_diff.cli.YamlNodeHandler())
 
         if header is None:

tests/cli/shared.stream.a.yaml

@@ -0,0 +1,4 @@
+---
+one: 1
+---
+two: 2

tests/cli/shared.stream.b.yaml

@@ -0,0 +1,4 @@
+---
+one: uno
+---
+two: 2

tests/cli/test_diff_tool.py

@@ -786,3 +786,33 @@ def test_yaml_custom_tags(capsys, expected, rpath):
     assert exit_code == 1
 
     assert captured.out == expected
+
+
+def test_yaml_streams(capsys, expected, rpath):
+    exit_code = nested_diff.diff_tool.App(
+        args=(
+            rpath('shared.stream.a.yaml'),
+            rpath('shared.stream.b.yaml'),
+        ),
+    ).run()
+
+    captured = capsys.readouterr()
+    assert captured.err == ''
+    assert exit_code == 1
+
+    assert captured.out == expected
+
+
+def test_yaml_stream_vs_single(capsys, expected, rpath):
+    exit_code = nested_diff.diff_tool.App(
+        args=(
+            rpath('shared.stream.a.yaml'),
+            rpath('shared.lists.b.yaml'),
+        ),
+    ).run()
+
+    captured = capsys.readouterr()
+    assert captured.err == ''
+    assert exit_code == 1
+
+    assert captured.out == expected

tests/cli/test_diff_tool.test_yaml_stream_vs_single.exp

@@ -0,0 +1,2 @@
+- ListOfDocuments([{'one': 1}, {'two': 2}])
++ [0, [1, 2], 3]

tests/cli/test_diff_tool.test_yaml_streams.exp

@@ -0,0 +1,5 @@
+# <ListOfDocuments>
+  [0]
+    {'one'}
+-     1
++     'uno'