tests: introduce a further variant of #2179

When working on a fix for this issue, we want to ensure we do not also affect
the case that currently (correctly) does not warn.

diff --git a/rtest/test_regression.py b/rtest/test_regression.py
index a69fc73be73d7920df5e5d26b409214867085d53..679d4fddc6a1e1fbe13c6127c4b46296ff2677a1 100644 (file)
--- a/rtest/test_regression.py
+++ b/rtest/test_regression.py
@@ -1376,6 +1376,29 @@ def test_2179():
   assert "Warning: no hard-coded metrics for" not in stderr, \
     "incorrect warning triggered"
 
+def test_2179_1():
+  """
+  processing a label with a line containing only a space should not yield a
+  warning
+  https://gitlab.com/graphviz/graphviz/-/issues/2179
+  """
+
+  # a graph containing a label with a line containing only a space
+  input = 'digraph "" {\n' \
+          '  0 -> 1 [fontname="Lato",label=< <br/>1>]\n' \
+          '}'
+
+  # run a graph with an empty label through Graphviz
+  with subprocess.Popen(["dot", "-Tsvg", "-o", os.devnull],
+                        stdin=subprocess.PIPE, stderr=subprocess.PIPE,
+                        universal_newlines=True) as p:
+    _, stderr = p.communicate(input)
+
+    assert p.returncode == 0
+
+  assert "Warning: no hard-coded metrics for" not in stderr, \
+    "incorrect warning triggered"
+
 def test_2185_1():
   """
   GVPR should deal with strings correctly