Harrison/improve data augmented generation docs (#390)

Co-authored-by: cameronccohen <cameron.c.cohen@gmail.com>
Co-authored-by: Cameron Cohen <cameron.cohen@quantco.com>

tests/unit_tests/test_text_splitter.py

@@ -1,6 +1,7 @@
 """Test text splitting functionality."""
 import pytest
 
+from langchain.docstore.document import Document
 from langchain.text_splitter import CharacterTextSplitter
 
 
@@ -35,3 +36,29 @@ def test_character_text_splitting_args() -> None:
     """Test invalid arguments."""
     with pytest.raises(ValueError):
         CharacterTextSplitter(chunk_size=2, chunk_overlap=4)
+
+
+def test_create_documents() -> None:
+    """Test create documents method."""
+    texts = ["foo bar", "baz"]
+    splitter = CharacterTextSplitter(separator=" ", chunk_size=3, chunk_overlap=0)
+    docs = splitter.create_documents(texts)
+    expected_docs = [
+        Document(page_content="foo"),
+        Document(page_content="bar"),
+        Document(page_content="baz"),
+    ]
+    assert docs == expected_docs
+
+
+def test_create_documents_with_metadata() -> None:
+    """Test create documents with metadata method."""
+    texts = ["foo bar", "baz"]
+    splitter = CharacterTextSplitter(separator=" ", chunk_size=3, chunk_overlap=0)
+    docs = splitter.create_documents(texts, [{"source": "1"}, {"source": "2"}])
+    expected_docs = [
+        Document(page_content="foo", metadata={"source": "1"}),
+        Document(page_content="bar", metadata={"source": "1"}),
+        Document(page_content="baz", metadata={"source": "2"}),
+    ]
+    assert docs == expected_docs