test(backends): remove now unused supported_to_timestamp_units backend flag (ibis-project#8940)

Test case configuration now happens through pytest markers.

depends on ibis-project#8939

---------

Co-authored-by: Gil Forsyth <gforsyth@users.noreply.github.com>

Author: kszucs

ibis/backends/clickhouse/tests/conftest.py

@@ -25,7 +25,6 @@
 class TestConf(ServiceBackendTest):
     check_dtype = False
     returned_timestamp_unit = "s"
-    supported_to_timestamp_units = {"s"}
     supports_json = False
     force_sort = True
     rounding_method = "half_to_even"

ibis/backends/exasol/tests/conftest.py

@@ -28,7 +28,6 @@ class TestConf(ServiceBackendTest):
     check_names = False
     supports_arrays = False
     returned_timestamp_unit = "us"
-    supported_to_timestamp_units = {"s", "ms", "us"}
     native_bool = True
     supports_structs = False
     supports_json = False

ibis/backends/pandas/tests/conftest.py

@@ -17,7 +17,6 @@
 
 class TestConf(BackendTest):
     check_names = False
-    supported_to_timestamp_units = BackendTest.supported_to_timestamp_units | {"ns"}
     returned_timestamp_unit = "ns"
     stateful = False
     rounding_method = "half_to_even"

ibis/backends/pyspark/tests/conftest.py

@@ -20,7 +20,6 @@ def set_pyspark_database(con, database):
 
 
 class TestConf(BackendTest):
-    supported_to_timestamp_units = {"s"}
     deps = ("pyspark",)
 
     def _load_data(self, **_: Any) -> None:

ibis/backends/tests/base.py

@@ -37,7 +37,6 @@ class BackendTest(abc.ABC):
     supports_arrays: bool = True
     "Whether backend supports Arrays / Lists"
     returned_timestamp_unit: str = "us"
-    supported_to_timestamp_units = {"s", "ms", "us"}
     native_bool: bool = True
     "Whether backend has native boolean types"
     supports_structs: bool = True