[sans-io] minor test improvements

test/mitmproxy/proxy2/conftest.py

@@ -7,7 +7,7 @@ from mitmproxy.proxy2 import context
 @pytest.fixture
 def tctx():
     return context.Context(
-        context.Client("client"),
-        context.Server("server"),
+        context.Client(("client", 1234)),
+        context.Server(("server", 42)),
         options.Options()
     )

test/mitmproxy/proxy2/tutils.py

@@ -135,7 +135,9 @@ class playbook:
 
             def _str(x):
                 arrow = ">" if isinstance(x, events.Event) else "<"
-                x = str(x).replace('Placeholder:', '')
+                x = str(x)\
+                    .replace('Placeholder:None', '<unset placeholder>')\
+                    .replace('Placeholder:', '')
                 return f"{arrow} {x}"
 
             diff = "\n".join(difflib.ndiff(