diff --git a/tests/test_vector_store.py b/tests/test_vector_store.py
new file mode 100644
index 0000000..a8c1ef9
--- /dev/null
+++ b/tests/test_vector_store.py
@@ -0,0 +1,124 @@
+import os
+from argparse import Namespace
+
+import pytest
+from unittest.mock import patch, MagicMock
+
+from sage.vector_store import PineconeVectorStore, MarqoVectorStore, build_vector_store_from_args
+
+mock_vectors = [({"id": "1", "text": "example"}, [0.1, 0.2, 0.3])]
+mock_namespace = "test_namespace"
+
+
+class TestVectorStore:
+    @pytest.fixture
+    def pinecone_store(self):
+        with patch("sage.vector_store.Pinecone"):
+            store = PineconeVectorStore(index_name="test_index", dimension=128, alpha=0.5)
+            yield store
+
+    @pytest.fixture
+    def marqo_store(self):
+        with patch("marqo.Client"):
+            store = MarqoVectorStore(url="http://localhost:8882", index_name="test_index")
+            yield store
+
+    @pytest.fixture
+    def mock_data_manager(self):
+        data_manager = MagicMock()
+        data_manager.walk.return_value = [("sample content", {})]
+        return data_manager
+
+    @pytest.fixture
+    def mock_nltk(self):
+        with patch("nltk.data.find") as mock_find:
+            mock_find.side_effect = LookupError
+            yield mock_find
+
+    @pytest.fixture
+    def mock_bm25_encoder(self):
+        with patch("sage.vector_store.BM25Encoder") as MockBM25Encoder:
+            mock_instance = MockBM25Encoder.return_value
+            mock_instance.encode_documents.return_value = [0.1, 0.2, 0.3]
+            mock_instance.fit = MagicMock()
+            mock_instance.dump = MagicMock()
+            yield mock_instance
+
+    def test_pinecone_vector_store_initialization(self, pinecone_store):
+        assert pinecone_store.index_name == "test_index"
+        assert pinecone_store.dimension == 128
+        assert pinecone_store.alpha == 0.5
+
+    def test_pinecone_vector_store_ensure_exists(self, pinecone_store):
+        pinecone_store.ensure_exists()
+        pinecone_store.client.create_index.assert_called_once()
+
+    def test_pinecone_vector_store_upsert_batch(self, pinecone_store):
+        pinecone_store.upsert_batch(mock_vectors, mock_namespace)
+        pinecone_store.client.Index().upsert.assert_called_once()
+
+    def test_marqo_vector_store_initialization(self, marqo_store):
+        assert marqo_store.index_name == "test_index"
+
+    def test_marqo_vector_store_ensure_exists(self, marqo_store):
+        # No specific assertion as ensure_exists is a no-op
+        marqo_store.ensure_exists()
+
+    def test_marqo_vector_store_upsert_batch(self, marqo_store):
+        # No specific assertion as upsert_batch is a no-op
+        marqo_store.upsert_batch(mock_vectors, mock_namespace)
+
+
+    def build_args(self, provider, alpha=1.0):
+        if provider == "pinecone":
+            return Namespace(
+                vector_store_provider="pinecone",
+                pinecone_index_name="test_index",
+                embedding_size=128,
+                retrieval_alpha=alpha,
+                index_namespace="test_namespace"
+            )
+        elif provider == "marqo":
+            return Namespace(
+                vector_store_provider="marqo",
+                marqo_url="http://localhost:8882",
+                index_namespace="test_index"
+            )
+
+    def build_bm25_cache_path(self):
+        return os.path.join(".bm25_cache", "test_namespace", "bm25_encoder.json")
+
+    def test_builds_pinecone_vector_store_with_default_bm25_encoder(self, pinecone_store, mock_bm25_encoder, mock_data_manager, mock_nltk):
+        args = self.build_args("pinecone", alpha=0.5)
+        store = build_vector_store_from_args(args, data_manager=mock_data_manager)
+        assert isinstance(store, PineconeVectorStore)
+        assert store.bm25_encoder is not None
+        mock_bm25_encoder.fit.assert_called_once()
+        mock_bm25_encoder.dump.assert_called_once_with(self.build_bm25_cache_path())
+
+    def test_builds_pinecone_vector_store_with_cached_bm25_encoder(self, pinecone_store, mock_bm25_encoder):
+        with patch("os.path.exists", return_value=True):
+            args = self.build_args("pinecone", alpha=0.5)
+            store = build_vector_store_from_args(args)
+            assert isinstance(store, PineconeVectorStore)
+            assert store.bm25_encoder is not None
+            mock_bm25_encoder.load.assert_called_once_with(path=self.build_bm25_cache_path())
+
+    def test_builds_pinecone_vector_store_without_bm25_encoder(self, pinecone_store):
+        args = self.build_args("pinecone", alpha=1.0)
+        store = build_vector_store_from_args(args)
+        assert isinstance(store, PineconeVectorStore)
+        assert store.bm25_encoder is None
+
+    def test_builds_marqo_vector_store(self):
+        args = self.build_args("marqo")
+        store = build_vector_store_from_args(args)
+        assert isinstance(store, MarqoVectorStore)
+
+    def test_raises_value_error_for_unrecognized_provider(self):
+        args = Namespace(vector_store_provider="unknown")
+        with pytest.raises(ValueError, match="Unrecognized vector store type unknown"):
+            build_vector_store_from_args(args)
+
+    if __name__ == '__main__':
+        pytest.main()
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