Add ImportBlock to allow extending existing pipelines

This is to enable the common case of a custom pipeline that
extends an existing pipeline, commonly either by prepending
or appending to the existing pipeline.

The format looks like e.g.:

```
version: "1.0"
blocks:
- <some blocks>
- name: import_child
  type: ImportBlock
  config:
    path: pipelines/full/knowledge.yaml
- <some more blocks>
```

Signed-off-by: Mark McLoughlin <[email protected]>

src/instructlab/sdg/importblock.py

@@ -0,0 +1,34 @@
+# SPDX-License-Identifier: Apache-2.0
+# Third Party
+from datasets import Dataset
+
+# Local
+from . import pipeline
+from .block import Block
+from .logger_config import setup_logger
+
+logger = setup_logger(__name__)
+
+
+class ImportBlock(Block):
+    def __init__(
+        self,
+        ctx,
+        block_name,
+        path,
+    ) -> None:
+        """
+        ImportBlock imports a chain of blocks from another pipeline config file.
+
+        Parameters:
+        - ctx (PipelineContext): A PipelineContext object containing runtime parameters.
+        - block_name (str): An identifier for this block.
+        - path (str): A path (absolute, or relative to the instructlab.sdg package) to a pipeline config file.
+        """
+        super().__init__(ctx, block_name)
+        self.path = path
+        self.pipeline = pipeline.Pipeline.from_file(self.ctx, self.path)
+
+    def generate(self, samples) -> Dataset:
+        logger.info("ImportBlock chaining to blocks from {self.path}")
+        return self.pipeline.generate(samples)

src/instructlab/sdg/pipeline.py

@@ -8,7 +8,7 @@
 import yaml
 
 # Local
-from . import filterblock, llmblock, utilblocks
+from . import filterblock, importblock, llmblock, utilblocks
 from .logger_config import setup_logger
 
 logger = setup_logger(__name__)
@@ -85,6 +85,7 @@ def generate(self, dataset) -> Dataset:
     "CombineColumnsBlock": utilblocks.CombineColumnsBlock,
     "ConditionalLLMBlock": llmblock.ConditionalLLMBlock,
     "FilterByValueBlock": filterblock.FilterByValueBlock,
+    "ImportBlock": importblock.ImportBlock,
     "LLMBlock": llmblock.LLMBlock,
     "SamplePopulatorBlock": utilblocks.SamplePopulatorBlock,
     "SelectorBlock": utilblocks.SelectorBlock,

tests/test_importblock.py

@@ -0,0 +1,103 @@
+# Standard
+from unittest.mock import MagicMock, patch
+import os
+import tempfile
+import unittest
+
+# Third Party
+from datasets import Dataset, Features, Value
+
+# First Party
+from instructlab.sdg.importblock import ImportBlock
+from instructlab.sdg.pipeline import Pipeline
+
+
+class TestImportBlockWithMockPipeline(unittest.TestCase):
+    @patch("instructlab.sdg.pipeline.Pipeline")
+    def setUp(self, mock_pipeline):
+        self.ctx = MagicMock()
+        self.block_name = "test_block"
+        self.path = "/path/to/config"
+        self.mock_pipeline = mock_pipeline
+        self.import_block = ImportBlock(self.ctx, self.block_name, self.path)
+        self.dataset = Dataset.from_dict({})
+
+    def test_initialization(self):
+        self.assertEqual(self.import_block.block_name, self.block_name)
+        self.assertEqual(self.import_block.path, self.path)
+        self.mock_pipeline.from_file.assert_called_once_with(self.ctx, self.path)
+
+    def test_generate(self):
+        self.mock_pipeline.from_file.return_value.generate.return_value = self.dataset
+        samples = self.import_block.generate(self.dataset)
+        self.mock_pipeline.from_file.return_value.generate.assert_called_once_with(
+            samples
+        )
+        self.assertEqual(samples, self.dataset)
+
+
+_CHILD_YAML = """\
+version: "1.0"
+blocks:
+- name: greater_than_thirty
+  type: FilterByValueBlock
+  config:
+    filter_column: age
+    filter_value: 30
+    operation: gt
+    convert_dtype: int
+"""
+
+
+_PARENT_YAML_FMT = """\
+version: "1.0"
+blocks:
+- name: forty_or_under
+  type: FilterByValueBlock
+  config:
+    filter_column: age
+    filter_value: 40
+    operation: le
+    convert_dtype: int
+- name: import_child
+  type: ImportBlock
+  config:
+    path: %s
+- name: big_bdays
+  type: FilterByValueBlock
+  config:
+    filter_column: age
+    filter_value:
+    - 30
+    - 40
+    operation: eq
+    convert_dtype: int
+"""
+
+
+class TestImportBlockWithFilterByValue(unittest.TestCase):
+    def setUp(self):
+        self.ctx = MagicMock()
+        self.ctx.num_procs = 1
+        self.child_yaml = self._write_tmp_yaml(_CHILD_YAML)
+        self.parent_yaml = self._write_tmp_yaml(_PARENT_YAML_FMT % self.child_yaml)
+        self.dataset = Dataset.from_dict(
+            {"age": ["25", "30", "35", "40", "45"]},
+            features=Features({"age": Value("string")}),
+        )
+
+    def tearDown(self):
+        os.remove(self.parent_yaml)
+        os.remove(self.child_yaml)
+
+    def _write_tmp_yaml(self, content):
+        tmp_file = tempfile.NamedTemporaryFile(delete=False, mode="w", suffix=".yaml")
+        tmp_file.write(content)
+        tmp_file.close()
+        return tmp_file.name
+
+    def test_generate(self):
+        pipeline = Pipeline.from_file(self.ctx, self.parent_yaml)
+        filtered_dataset = pipeline.generate(self.dataset)
+        self.assertEqual(len(filtered_dataset), 1)
+        self.assertEqual(filtered_dataset["age"], [40])