pytest: Actually make sure that the direcory exists

Some tests may not spawn a node at all, so make sure that our assumption that
the directory exists in the fixture cleanup is correct by creating the
directory.

contrib/pyln-testing/pyln/testing/fixtures.py

@@ -41,6 +41,9 @@ def directory(request, test_base_dir, test_name):
     directory = os.path.join(test_base_dir, "{}_{}".format(test_name, __attempts[test_name]))
     request.node.has_errors = False
 
+    if not os.path.exists(directory):
+        os.makedirs(directory)
+
     yield directory
 
     # This uses the status set in conftest.pytest_runtest_makereport to

tests/test_onion.py

@@ -30,7 +30,6 @@ pubkeys = [
 def test_onion(directory, oniontool):
     """ Generate a 5 hop onion and then decode it.
     """
-    os.makedirs(directory)
     tempfile = os.path.join(directory, 'onion')
     out = subprocess.check_output(
         [oniontool, 'generate'] + pubkeys
@@ -53,7 +52,6 @@ def test_onion(directory, oniontool):
 def test_rendezvous_onion(directory, oniontool):
     """Create a compressed onion, decompress it at the RV node and then forward normally.
     """
-    os.makedirs(directory)
     tempfile = os.path.join(directory, 'onion')
     out = subprocess.check_output(
         [oniontool, '--rendezvous-id', pubkeys[0], 'generate'] + pubkeys