Add overlapping (consistent) flake cache insert test

* Additionally, update `insert`'s input type hint to support None values
  (as they are already selectable and (one shot) insertable).
  This is necessary to appease the linter wrt the added test.

pkgs/clan-cli/clan_cli/flake.py

@@ -154,7 +154,9 @@ class FlakeCacheEntry:
             self.value = value
 
     def insert(
-        self, value: str | float | dict[str, Any] | list[Any], selectors: list[Selector]
+        self,
+        value: str | float | dict[str, Any] | list[Any] | None,
+        selectors: list[Selector],
     ) -> None:
         selector: Selector
         if selectors == []:

pkgs/clan-cli/tests/test_flake_caching.py

@@ -17,6 +17,14 @@ def test_select() -> None:
     assert not test_cache.is_cached(["x", "z", 1])
 
 
+def test_insert() -> None:
+    test_cache = FlakeCacheEntry({}, [])
+    # Inserting the same thing twice should succeed
+    test_cache.insert(None, ["nix"])
+    test_cache.insert(None, ["nix"])
+    assert test_cache.select(["nix"]) is None
+
+
 def test_out_path() -> None:
     testdict = {"x": {"y": [123, 345, 456], "z": "/nix/store/bla"}}
     test_cache = FlakeCacheEntry(testdict, [])