Better test following review

Author: Pierre-Sassoulas

tests/test_formatter.py

@@ -1,12 +1,14 @@
-import pytest
+from typing import Set
 
 from pydocstringformatter.formatting import FORMATTERS
-from pydocstringformatter.formatting.base import Formatter
 
 
-@pytest.mark.parametrize(
-    "formatter,expected", zip(FORMATTERS, ["beginning-quotes", "closing-quotes"])
-)
-def test_name(formatter: Formatter, expected: str) -> None:
-    """Test that the name do not change as they're used in the options."""
-    assert formatter.name == expected
+def test_name() -> None:
+    """Test that each formatter name exists and is unique."""
+    formatter_names: Set[str] = set()
+    for formatter in FORMATTERS:
+        assert formatter.name, "Each formatter should have a name set."
+        assert (
+            formatter.name not in formatter_names
+        ), "Each formatter should have an unique name."
+        formatter_names.add(formatter.name)