Add documentation and implementation for custom pgvector knowledge storage (#2883)

Co-Authored-By: Joe Moura <joao@crewai.com>

tests/knowledge/pgvector_knowledge_storage_test.py

@@ -0,0 +1,90 @@
+import os
+import pytest
+from typing import Dict, Any, List
+from unittest.mock import patch, MagicMock
+
+from crewai.knowledge.storage.pgvector_knowledge_storage import PGVectorKnowledgeStorage
+
+class MockSession:
+    def __init__(self):
+        self.queries = []
+        self.commits = 0
+        self.rollbacks = 0
+        self.closes = 0
+    
+    def query(self, *args, **kwargs):
+        return self
+    
+    def filter(self, *args, **kwargs):
+        return self
+    
+    def first(self):
+        return None
+    
+    def add(self, *args, **kwargs):
+        pass
+    
+    def commit(self):
+        self.commits += 1
+    
+    def rollback(self):
+        self.rollbacks += 1
+    
+    def close(self):
+        self.closes += 1
+    
+    def execute(self, *args, **kwargs):
+        return self
+    
+    def fetchall(self):
+        return [
+            ("doc1", "This is a test document", '{"source": "test"}', 0.9),
+            ("doc2", "Another test document", '{"source": "test"}', 0.8),
+            ("doc3", "A third test document", '{"source": "test"}', 0.7),
+        ]
+
+@pytest.fixture
+def mock_embedder():
+    return lambda x: [[0.1] * 1536 for _ in range(len(x))]
+
+@pytest.fixture
+def mock_session():
+    return MockSession()
+
+@pytest.fixture
+def mock_session_maker(mock_session):
+    def session_maker():
+        return mock_session
+    return session_maker
+
+@pytest.fixture
+def mock_engine():
+    return MagicMock()
+
+@pytest.fixture
+def pgvector_storage(mock_embedder, mock_session_maker, mock_engine):
+    with patch("crewai.knowledge.storage.pgvector_knowledge_storage.create_engine", return_value=mock_engine), \
+         patch("crewai.knowledge.storage.pgvector_knowledge_storage.sessionmaker", return_value=mock_session_maker), \
+         patch("crewai.knowledge.storage.pgvector_knowledge_storage.Base.metadata.create_all"):
+        storage = PGVectorKnowledgeStorage(connection_string="postgresql://test:test@localhost:5432/test")
+        storage.embedder = mock_embedder
+        return storage
+
+def test_search(pgvector_storage, mock_session):
+    results = pgvector_storage.search(["test query"], limit=3, score_threshold=0.5)
+    
+    assert len(results) == 3
+    assert results[0]["id"] == "doc1"
+    assert results[0]["context"] == "This is a test document"
+    assert results[0]["score"] == 0.9
+    
+    assert mock_session.closes == 1
+
+def test_save(pgvector_storage, mock_session):
+    documents = ["Document 1", "Document 2"]
+    metadata = [{"source": "test1"}, {"source": "test2"}]
+    
+    pgvector_storage.save(documents, metadata)
+    
+    assert mock_session.commits == 1
+    assert mock_session.closes == 1