Increase test coverage

singer_sdk/batch.py

@@ -12,9 +12,10 @@
     from singer_sdk.helpers._batch import BatchConfig
 
 _T = t.TypeVar("_T")
+_B = t.TypeVar("_B", bound="BaseBatcher")
 
 
-def __getattr__(name: str) -> t.Any:  # noqa: ANN401
+def __getattr__(name: str) -> t.Any:  # noqa: ANN401 # pragma: no cover
     if name == "JSONLinesBatcher":
         warnings.warn(
             "The class JSONLinesBatcher was moved to singer_sdk.contrib.batch_encoder_jsonl.",  # noqa: E501
@@ -98,23 +99,35 @@ def get_batches(self, records: t.Iterator[dict]) -> t.Iterator[list[str]]:
 
         Returns:
             A list of file paths (called a manifest).
+        """
+        encoding_format = self.batch_config.encoding.format
+        batcher_type: type[BaseBatcher] = self.get_batcher(encoding_format)
+        batcher = batcher_type(
+            self.tap_name,
+            self.stream_name,
+            self.batch_config,
+        )
+        return batcher.get_batches(records)
+
+    @classmethod
+    def get_batcher(cls, name: str) -> type[_B]:
+        """Get a batcher by name.
+
+        Args:
+            name: The name of the batcher.
+
+        Returns:
+            The batcher class.
 
         Raises:
-            ValueError: If unsupported format given.
+            ValueError: If the batcher is not found.
         """
-        encoding_format = self.batch_config.encoding.format
         plugins = entry_points(group="singer_sdk.batch_encoders")
 
         try:
-            plugin = next(filter(lambda x: x.name == encoding_format, plugins))
+            plugin = next(filter(lambda x: x.name == name, plugins))
         except StopIteration:
-            message = f"Unsupported batch format: {encoding_format}"
+            message = f"Unsupported batcher: {name}"
             raise ValueError(message) from None
 
-        batcher_type: type[Batcher] = plugin.load()
-        batcher = batcher_type(
-            self.tap_name,
-            self.stream_name,
-            self.batch_config,
-        )
-        return batcher.get_batches(records)
+        return plugin.load()

singer_sdk/sinks/core.py

@@ -526,9 +526,6 @@ def process_batch_files(
         Raises:
             NotImplementedError: If the batch file encoding is not supported.
         """
-        spec = importlib.util.find_spec("pyarrow")
-        if spec:
-            import pyarrow.parquet as pq
         file: GzipFile | t.IO
         storage: StorageTarget | None = None
 
@@ -550,7 +547,12 @@ def process_batch_files(
                     )
                     context = {"records": [json.loads(line) for line in context_file]}  # type: ignore[attr-defined]
                     self.process_batch(context)
-            elif spec and encoding.format == BatchFileFormat.PARQUET:
+            elif (
+                importlib.util.find_spec("pyarrow")
+                and encoding.format == BatchFileFormat.PARQUET
+            ):
+                import pyarrow.parquet as pq
+
                 with storage.fs(create=False) as batch_fs, batch_fs.open(
                     tail,
                     mode="rb",

tests/core/test_batch.py

@@ -109,6 +109,11 @@ def test_storage_from_url(file_url: str, root: str):
     assert target.root == root
 
 
+def test_get_unsupported_batcher():
+    with pytest.raises(ValueError, match="Unsupported batcher"):
+        Batcher.get_batcher("unsupported")
+
+
 @pytest.mark.parametrize(
     "file_url,expected",
     [