Add unit tests for sdg.filterblock

This new file introduces some unit tests for the filterblock module.
A previous commit introduced a bug fix to ensure that unexpected data
does not cause this block to break. These tests exercise those fixes.
The tests introduced here will run automatically in CI and help ensure
that the problem does not reoccur.

Signed-off-by: Russell Bryant <rbryant@redhat.com>

Author: russellb

tests/test_filterblock.py

@@ -0,0 +1,31 @@
+# Standard
+from unittest.mock import patch
+import operator
+import unittest
+
+# Third Party
+from datasets import Dataset, Features, Value
+
+# First Party
+from instructlab.sdg.filterblock import FilterByValueBlock
+
+
+class TestFilterByValueBlock(unittest.TestCase):
+    def setUp(self):
+        self.block = FilterByValueBlock(
+            filter_column="age",
+            filter_value=30,
+            operation=operator.eq,
+            convert_dtype=int,
+        )
+        self.dataset = Dataset.from_dict(
+            {"age": ["25", "30", "35", "forty", "45"]},
+            features=Features({"age": Value("string")}),
+        )
+
+    @patch("instructlab.sdg.filterblock.logger")
+    def test_generate_mixed_types(self, mock_logger):
+        filtered_dataset = self.block.generate(self.dataset)
+        self.assertEqual(len(filtered_dataset), 1)
+        self.assertEqual(filtered_dataset["age"], [30])
+        mock_logger.error.assert_called()