test: add backend flow test (#995)

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## Description
Simple Cognee endpoint testing

## DCO Affirmation
I affirm that all code in every commit of this pull request conforms to
the terms of the Topoteretes Developer Certificate of Origin.

---------

Co-authored-by: Boris <boris@topoteretes.com>

cognee/tests/test_cognee_server_start.py

@@ -4,6 +4,7 @@ import time
 import os
 import signal
 import requests
+from pathlib import Path
 import sys
 
 
@@ -27,7 +28,7 @@ class TestCogneeServerStart(unittest.TestCase):
             preexec_fn=os.setsid,
         )
         # Give the server some time to start
-        time.sleep(30)
+        time.sleep(35)
 
         # Check if server started with errors
         if cls.server_process.poll() is not None:
@@ -54,6 +55,64 @@ class TestCogneeServerStart(unittest.TestCase):
         self.assertIn("message", root_response.json())
         self.assertEqual(root_response.json()["message"], "Hello, World, I am alive!")
 
+        # Login request
+        url = "http://127.0.0.1:8000/api/v1/auth/login"
+        form_data = {
+            "username": "default_user@example.com",
+            "password": "default_password",
+        }
+        login_response = requests.post(url, data=form_data, timeout=10)
+        login_response.raise_for_status()  # raises on HTTP 4xx/5xx
+
+        # Define Bearer token to use for authorization
+        auth_var = (
+            "Bearer " + login_response.json()["access_token"]
+        )  # e.g. "Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6..."
+
+        # Add request
+        url = "http://127.0.0.1:8000/api/v1/add"
+        file_path = Path(os.path.join(Path(__file__).parent, "test_data/example.png"))
+        headers = {"Authorization": auth_var}
+
+        form_data = {"datasetName": "test"}
+
+        file = {
+            "data": (
+                file_path.name,
+                open(file_path, "rb"),
+            )
+        }
+
+        add_response = requests.post(url, headers=headers, data=form_data, files=file, timeout=15)
+        add_response.raise_for_status()  # raise if HTTP 4xx/5xx
+
+        # Cognify request
+        url = "http://127.0.0.1:8000/api/v1/cognify"
+        headers = {
+            "Authorization": auth_var,
+            "Content-Type": "application/json",
+        }
+
+        payload = {"datasets": ["test"]}
+
+        cognify_response = requests.post(url, headers=headers, json=payload, timeout=15)
+        cognify_response.raise_for_status()  # raises on HTTP 4xx/5xx
+
+        # TODO: Add test to verify cognify pipeline is complete before testing search
+
+        # Search request
+        url = "http://127.0.0.1:8000/api/v1/search"
+
+        headers = {
+            "Authorization": auth_var,
+            "Content-Type": "application/json",
+        }
+
+        payload = {"searchType": "GRAPH_COMPLETION", "query": "What's in the document?"}
+
+        search_response = requests.post(url, headers=headers, json=payload, timeout=15)
+        search_response.raise_for_status()  # raises on HTTP 4xx/5xx
+
 
 if __name__ == "__main__":
     unittest.main()