Apply assorted ruff/flake8-simplify rules (SIM) (#2259)

* Apply ruff/flake8-simplify rule SIM103

SIM103 Return the condition directly

* Apply ruff/flake8-simplify rule SIM118

SIM118 Use `key in dict` instead of `key in dict.keys()`

src/zarr/core/indexing.py

@@ -218,9 +218,7 @@ def is_scalar(value: Any, dtype: np.dtype[Any]) -> bool:
         return True
     if hasattr(value, "shape") and value.shape == ():
         return True
-    if isinstance(value, tuple) and dtype.names and len(value) == len(dtype.names):
-        return True
-    return False
+    return isinstance(value, tuple) and dtype.names is not None and len(value) == len(dtype.names)
 
 
 def is_pure_fancy_indexing(selection: Any, ndim: int) -> bool:

src/zarr/store/zip.py

@@ -110,10 +110,7 @@ async def clear(self) -> None:
 
     async def empty(self) -> bool:
         with self._lock:
-            if self._zf.namelist():
-                return False
-            else:
-                return True
+            return not self._zf.namelist()
 
     def __str__(self) -> str:
         return f"zip://{self.path}"

src/zarr/testing/store.py

@@ -248,7 +248,7 @@ async def test_list_prefix(self, store: S) -> None:
         for prefix in prefixes:
             observed = tuple(sorted(await _collect_aiterator(store.list_prefix(prefix))))
             expected: tuple[str, ...] = ()
-            for key in store_dict.keys():
+            for key in store_dict:
                 if key.startswith(prefix):
                     expected += (key.removeprefix(prefix),)
             expected = tuple(sorted(expected))
@@ -267,7 +267,7 @@ async def test_list_dir(self, store: S) -> None:
         await store._set_many(store_dict.items())
 
         keys_observed = await _collect_aiterator(store.list_dir(root))
-        keys_expected = {k.removeprefix(root + "/").split("/")[0] for k in store_dict.keys()}
+        keys_expected = {k.removeprefix(root + "/").split("/")[0] for k in store_dict}
 
         assert sorted(keys_observed) == sorted(keys_expected)