Add test and docstrings

Signed-off-by: Emerson Knapp <emerson.b.knapp@gmail.com>

ros2node/ros2node/api/__init__.py

@@ -50,6 +50,14 @@ def parse_node_name(node_name):
 
 
 def annotate_duplicate_nodes(node_names: List[NodeName]) -> Tuple[bool, List[str]]:
+    """
+    Annotate a list of node names with a warnings if names are not unique.
+
+    :param node_names: list of all NodeNames observed in the graph
+    :return Tuple containing:
+        bool of whether any duplicate nodes were found
+        list of all names as strings, with or without annotations, for printing
+    """
     annotation_string = ' (non-unique name)'
 
     any_duplicates = False

ros2node/ros2node/verb/list.py

@@ -40,5 +40,6 @@ def main(self, *, args):
         elif node_names:
             has_duplicates, sorted_names = annotate_duplicate_nodes(node_names)
             if has_duplicates:
-                print('# WARNING: There are nodes in the graph that share a name')
+                print('# WARNING: Be aware that are nodes in the graph that share an exact name, '
+                      'this can have unintended side effects.')
             print(*sorted_names, sep='\n')

ros2node/test/test_node.py

@@ -12,6 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from ros2node.api import annotate_duplicate_nodes
+from ros2node.api import NodeName
 from ros2node.api import parse_node_name
 
 
@@ -34,3 +36,28 @@ def test_parse_node_name():
     assert name.full_name == '/ns/talker'
     assert name.namespace == '/ns'
     assert name.name == 'talker'
+
+
+def test_duplicate_names():
+    all_unique_names = [
+        NodeName('foo', 'ns_foo', 'ns_foo/foo'),
+        NodeName('bar', 'ns_foo', 'ns_foo/bar'),
+    ]
+
+    any_duplicates, printable_names = annotate_duplicate_nodes(all_unique_names)
+    assert not any_duplicates
+    assert printable_names == [
+        'ns_foo/bar',
+        'ns_foo/foo',
+    ]
+
+    all_unique_names = [
+        NodeName('foo', 'ns_foo', 'ns_foo/foo'),
+        NodeName('foo', 'ns_foo', 'ns_foo/foo'),
+    ]
+    any_duplicates, printable_names = annotate_duplicate_nodes(all_unique_names)
+    assert any_duplicates
+    assert printable_names == [
+        'ns_foo/foo (non-unique name)',
+        'ns_foo/foo (non-unique name)',
+    ]