[VectorStore] Improvement: Improve chroma vector store (#28524)

- Complete unit test
- Fix spelling error

libs/partners/chroma/langchain_chroma/vectorstores.py

@@ -758,7 +758,7 @@ class Chroma(VectorStore):
 
         The most similar documents will have the lowest relevance score. Default
         relevance score function is euclidean distance. Distance metric must be
-        provided in `collection_metadata` during initizalition of Chroma object.
+        provided in `collection_metadata` during initialization of Chroma object.
         Example: collection_metadata={"hnsw:space": "cosine"}. Available distance
         metrics are: 'cosine', 'l2' and 'ip'.
 

libs/partners/chroma/tests/unit_tests/test_vectorstores.py

@@ -13,3 +13,18 @@ def test_initialization() -> None:
         texts=texts,
         embedding=FakeEmbeddings(size=10),
     )
+
+
+def test_similarity_search() -> None:
+    """Test similarity search by Chroma."""
+    texts = ["foo", "bar", "baz"]
+    metadatas = [{"page": str(i)} for i in range(len(texts))]
+    docsearch = Chroma.from_texts(
+        collection_name="test_collection",
+        texts=texts,
+        embedding=FakeEmbeddings(size=10),
+        metadatas=metadatas,
+    )
+    output = docsearch.similarity_search("foo", k=1)
+    docsearch.delete_collection()
+    assert len(output) == 1