fix 'dot' test helper failing to encode string input

When asking the `dot` helper function to process a graph from inline input to a
binary output format, the `universal_newlines=True` parameter would not be
passed to the underlying `subprocess.check_output` call, resulting in failure to
encode the input. That is, something like the following:

  dot("png:gd", source="digraph { a -> b; }")

would result in:

  self = <subprocess.Popen object at 0x7fbb862ae390>
      def _communicate(self, input, endtime, orig_timeout):
  …
  >           input_view = memoryview(self._input)
  E           TypeError: memoryview: a bytes-like object is required, not 'str'
  /usr/lib64/python3.6/subprocess.py:1519: TypeError

Note that this problem was latent, as no usage fitting the above scenario
currently exists. Something like this will be introduced in a future commit.

Gitlab: related to #1786

diff --git a/rtest/gvtest.py b/rtest/gvtest.py
index 390ae6b14e8b7b35382450e1850e2b17b0ee589b..4bae0fea322fd4f46b78d2b2f9613505789449a9 100644 (file)
--- a/rtest/gvtest.py
+++ b/rtest/gvtest.py
@@ -81,14 +81,18 @@ def dot(T: str, source_file: Optional[Path] = None, source: Optional[str] = None
     "one of `source_file` or `source` needs to be provided"
 
   # is the output format a textual format?
+  output_is_text = T in ("cmapx", "json", "pic", "svg", "xdot")
+
   kwargs = {}
-  if T in ("cmapx", "json", "pic", "svg", "xdot"):
+  if output_is_text:
     kwargs["universal_newlines"] = True
 
   args = ["dot", f"-T{T}"]
 
   if source_file is not None:
     args += [source_file]
+  elif not output_is_text:
+    kwargs["input"] = source.encode("utf-8")
   else:
     kwargs["input"] = source