Using real objects is considered polite

Previously, ToddlerBase and derived classes were used directly, but none
of the methods is marked as a class or static method. Amazingly enough,
it worked regardless. It's useful to have a constructor, though, so do
things conventionally.

As we can't just monkey-patch the classes then, use the shared `toddler`
fixture which creates the object for the test methods that need it.

Signed-off-by: Nils Philippsen <nils@redhat.com>

tests/plugins/test_debug.py

@@ -1,16 +1,17 @@
 import fedora_messaging.api
 
-import toddlers.plugins.debug
+from toddlers.plugins.debug import DebugToddler
 
 
 class TestDebugToddler:
-    def test_accepts_topic(self):
-        assert toddlers.plugins.debug.DebugToddler.accepts_topic("foo.bar")
 
-    def test_process(self):
+    toddler_cls = DebugToddler
+
+    def test_accepts_topic(self, toddler):
+        assert toddler.accepts_topic("foo.bar")
+
+    def test_process(self, toddler):
         msg = fedora_messaging.api.Message()
         msg.id = 123
         msg.topic = "toddlers.test.topic"
-        assert (
-            toddlers.plugins.debug.DebugToddler.process(config={}, message=msg) is None
-        )
+        assert toddler.process(config={}, message=msg) is None