docs(tests): add API docs for the testing base classes

refactor(tests): more documentation

docs/_quarto.yml

@@ -543,3 +543,10 @@ quartodoc:
         - Options
         - Repr
         - SQL
+
+    - title: Contributing
+      desc: "Ibis Backend Developer Documentation"
+      package: ibis.backends.tests.base
+      contents:
+        - BackendTest
+        - ServiceBackendTest

docs/contribute/05_reference.qmd

@@ -0,0 +1,37 @@
+---
+title: "Test Class Reference"
+---
+
+This page provides a partial reference to the attributes, methods, properties
+and class-level variables that are used to help configure a backend for the Ibis
+test suite.
+
+Contributors are encouraged to look over the methods and class-level variables
+in `ibis/backends/tests/base.py`.
+
+To add a new backend test configuration import one of `BackendTest` or
+`ServiceBackendTest` into a `conftest.py` file with the path
+`ibis/backends/{backend_name}/tests/conftest.py`.  Then update / override the
+relevant class-level variables and methods.
+
+```python
+from ibis.backends.tests.base import BackendTest
+
+class TestConf(BackendTest):
+    """Backend-specific class with information for testing."""
+
+    supports_divide_by_zero = True
+    supports_floating_modulus = False
+    returned_timestamp_unit = "us"
+    supports_structs = True
+    supports_json = True
+    check_names = False
+    force_sort = True
+
+    @staticmethod
+    def connect(*args, **kwargs):
+        ...
+```
+
+{{< include ../reference/BackendTest.qmd >}}
+{{< include ../reference/ServiceBackendTest.qmd >}}

ibis/backends/bigquery/tests/conftest.py

@@ -34,7 +34,7 @@ class TestConf(BackendTest):
     supports_structs = True
     supports_json = True
     check_names = False
-    force_sort_before_comparison = True
+    force_sort = True
     deps = ("google.cloud.bigquery",)
 
     @staticmethod

ibis/backends/clickhouse/tests/conftest.py

@@ -29,7 +29,7 @@ class TestConf(ServiceBackendTest):
     supported_to_timestamp_units = {"s"}
     supports_floating_modulus = False
     supports_json = False
-    force_sort_before_comparison = True
+    force_sort = True
     rounding_method = "half_to_even"
     data_volume = "/var/lib/clickhouse/user_files/ibis"
     service_name = "clickhouse"

ibis/backends/flink/tests/conftest.py

@@ -11,7 +11,7 @@
 
 class TestConf(BackendTest):
     supports_structs = False
-    force_sort_before_comparison = True
+    force_sort = True
     deps = "pandas", "pyflink"
 
     @staticmethod

ibis/backends/impala/tests/conftest.py

@@ -31,7 +31,7 @@ class TestConf(BackendTest):
     returned_timestamp_unit = "s"
     supports_structs = False
     supports_json = False
-    force_sort_before_comparison = True
+    force_sort = True
     deps = "fsspec", "requests", "impala"
 
     def _load_data(self, **_: Any) -> None:

ibis/backends/tests/base.py

@@ -59,7 +59,7 @@ class BackendTest(abc.ABC):
     "Whether special handling is needed for running a multi-process pytest run."
     supports_tpch: bool = False
     "Child class defines a `load_tpch` method that loads the required TPC-H tables into a connection."
-    force_sort_before_comparison = False
+    force_sort = False
     "Sort results before comparing against reference computation."
     rounding_method: Literal["away_from_zero", "half_to_even"] = "away_from_zero"
     "Name of round method to use for rounding test comparisons."
@@ -163,6 +163,7 @@ def load_data(
 
     @classmethod
     def skip_if_missing_deps(cls) -> None:
+        """Add an `importorskip` for any missing dependencies."""
         for dep in cls.deps:
             pytest.importorskip(dep)
 
@@ -176,7 +177,11 @@ def postload(self, **_):  # noqa: B027
     def assert_series_equal(
         cls, left: pd.Series, right: pd.Series, *args: Any, **kwargs: Any
     ) -> None:
-        if cls.force_sort_before_comparison:
+        """Compare two Pandas Series, optionally ignoring order, dtype, and column name.
+
+        `force_sort`, `check_dtype`, and `check_names` are set as class-level variables.
+        """
+        if cls.force_sort:
             left = left.sort_values().reset_index(drop=True)
             right = right.sort_values().reset_index(drop=True)
         kwargs.setdefault("check_dtype", cls.check_dtype)
@@ -187,7 +192,11 @@ def assert_series_equal(
     def assert_frame_equal(
         cls, left: pd.DataFrame, right: pd.DataFrame, *args: Any, **kwargs: Any
     ) -> None:
-        if cls.force_sort_before_comparison:
+        """Compare two Pandas DataFrames optionally ignoring order, and dtype.
+
+        `force_sort`, and `check_dtype` are set as class-level variables.
+        """
+        if cls.force_sort:
             columns = list(set(left.columns) & set(right.columns))
             left = left.sort_values(by=columns)
             right = right.sort_values(by=columns)
@@ -344,9 +353,14 @@ class ServiceBackendTest(BackendTest):
     @property
     @abc.abstractmethod
     def test_files(self) -> Iterable[Path]:
+        """Returns an iterable of test files to load into a Docker container before testing."""
         ...
 
     def preload(self):
+        """Use `docker compose cp` to copy all files from `test_files` into a container.
+
+        `service_name` and `data_volume` are set as class-level variables.
+        """
         service = self.service_name
         data_volume = self.data_volume
         with concurrent.futures.ThreadPoolExecutor() as e: