Add tests for alternate mail subjects

chatmaild/src/chatmaild/tests/plugin.py

@@ -71,11 +71,11 @@ def maildata(request):
 
     assert datadir.exists(), datadir
 
-    def maildata(name, from_addr, to_addr):
+    def maildata(name, **kwargs):
         # Using `.read_bytes().decode()` instead of `.read_text()` to preserve newlines.
         data = datadir.joinpath(name).read_bytes().decode()
 
-        text = data.format(from_addr=from_addr, to_addr=to_addr)
+        text = data.format(**kwargs)
         return BytesParser(policy=policy.default).parsebytes(text.encode())
 
     return maildata