tools.memories, test: fix SopelIdentifierMemory.setdefault() behavior

sopel/tools/memories.py

@@ -206,6 +206,9 @@ def __contains__(self, key):
     def __setitem__(self, key: Optional[str], value):
         super().__setitem__(self._make_key(key), value)
 
+    def setdefault(self, key: str, default=None):
+        return super().setdefault(self._make_key(key), default)
+
     def __delitem__(self, key: str):
         super().__delitem__(self._make_key(key))
 

test/tools/test_tools_memories.py

@@ -64,6 +64,26 @@ def test_sopel_identifier_memory_channel_str():
     assert memory['#AdminChannel'] == test_value
 
 
+def test_sopel_identifier_memory_setdefault():
+    memory = memories.SopelIdentifierMemory()
+    assert 'foo' not in memory
+
+    memory.setdefault('Foo')
+    assert len(memory) == 1
+    assert 'foo' in memory
+    assert 'fOO' in memory
+    assert memory['fOo'] is None
+
+    memory.setdefault('bAr', 'DEFAULT')
+    assert len(memory) == 2
+    assert 'FoO' in memory
+    assert 'BaR' in memory
+    assert memory['Bar'] == 'DEFAULT'
+
+    assert memory.setdefault('baR', 'different') == 'DEFAULT'
+    assert len(memory) == 2  # still, that is
+
+
 def test_sopel_identifier_memory_copy():
     memory = memories.SopelIdentifierMemory()
     memory['SomeCamelCase'] = True