test: add comprehensive unit tests for /logs/ API endpoints (closes #1)

Added pytest-based unit tests for /logs/ endpoints covering:
- POST /logs/ success with valid payload
- POST /logs/ error cases: missing fields, empty body, invalid data types, wrong content-type
- GET /logs/ success, pagination (skip/limit), and after-creation assertions
- GET /logs/ error cases: invalid skip type, negative limit

Resolves issue #1: Add unit tests for /logs/ API endpoints

Author: DHANUSHGCODE

backend/tests/test_logs.py

@@ -1,22 +1,121 @@
+import pytest
 from fastapi.testclient import TestClient
 from backend.main import app
 
 client = TestClient(app)
 
-def test_create_log():
+VALID_PAYLOAD = {
+    "source_ip": "10.0.0.1",
+    "destination_ip": "10.0.0.2",
+    "protocol": "TCP",
+    "bytes_transferred": 1234,
+    "event_type": "normal",
+    "details": "test log entry"
+}
+
+
+# --- POST /logs/ Tests ---
+
+def test_create_log_success():
+    """Test POST /logs/ with a valid payload returns 200 or 201."""
+    resp = client.post("/logs/", json=VALID_PAYLOAD)
+    assert resp.status_code in (200, 201), f"Expected 200/201, got {resp.status_code}"
+    data = resp.json()
+    assert isinstance(data, dict)
+
+
+def test_create_log_missing_required_field():
+    """Test POST /logs/ with missing required field returns 422 Unprocessable Entity."""
     payload = {
-        "source_ip": "10.0.0.1",
         "destination_ip": "10.0.0.2",
         "protocol": "TCP",
         "bytes_transferred": 1234,
-        "event_type": "normal",
-        "details": "test log"
+        "event_type": "normal"
+        # source_ip is missing
     }
     resp = client.post("/logs/", json=payload)
+    assert resp.status_code == 422, f"Expected 422, got {resp.status_code}"
+
+
+def test_create_log_invalid_payload_empty_body():
+    """Test POST /logs/ with empty body returns 422."""
+    resp = client.post("/logs/", json={})
+    assert resp.status_code == 422, f"Expected 422, got {resp.status_code}"
+
+
+def test_create_log_invalid_data_type():
+    """Test POST /logs/ with wrong data type for bytes_transferred returns 422."""
+    payload = {**VALID_PAYLOAD, "bytes_transferred": "not_a_number"}
+    resp = client.post("/logs/", json=payload)
+    assert resp.status_code == 422, f"Expected 422, got {resp.status_code}"
+
+
+def test_create_log_response_structure():
+    """Test POST /logs/ response contains expected fields."""
+    resp = client.post("/logs/", json=VALID_PAYLOAD)
     assert resp.status_code in (200, 201)
+    data = resp.json()
+    # Response should be a dict (log record)
+    assert isinstance(data, dict)
+
 
-def test_list_logs():
+# --- GET /logs/ Tests ---
+
+def test_list_logs_success():
+    """Test GET /logs/ returns 200 with a list or paginated dict."""
+    resp = client.get("/logs/")
+    assert resp.status_code == 200, f"Expected 200, got {resp.status_code}"
+    data = resp.json()
+    assert isinstance(data, (list, dict)), "Response should be a list or dict"
+
+
+def test_list_logs_pagination_skip():
+    """Test GET /logs/ with skip query parameter."""
+    resp = client.get("/logs/?skip=0&limit=5")
+    assert resp.status_code == 200, f"Expected 200, got {resp.status_code}"
+    data = resp.json()
+    assert isinstance(data, (list, dict))
+
+
+def test_list_logs_pagination_limit():
+    """Test GET /logs/ with limit query parameter returns at most limit items."""
+    resp = client.get("/logs/?limit=2")
+    assert resp.status_code == 200, f"Expected 200, got {resp.status_code}"
+    data = resp.json()
+    if isinstance(data, list):
+        assert len(data) <= 2, f"Expected at most 2 results, got {len(data)}"
+
+
+def test_list_logs_after_creation():
+    """Test GET /logs/ returns logs after a POST."""
+    # Create a log first
+    client.post("/logs/", json=VALID_PAYLOAD)
     resp = client.get("/logs/")
     assert resp.status_code == 200
     data = resp.json()
-    assert isinstance(data, list) or isinstance(data, dict)
+    if isinstance(data, list):
+        assert len(data) >= 1, "Expected at least 1 log after creation"
+    elif isinstance(data, dict):
+        # Paginated response
+        items = data.get("items", data.get("logs", data.get("results", [])))
+        assert len(items) >= 1
+
+
+# --- Error / Edge Case Tests ---
+
+def test_create_log_no_content_type():
+    """Test POST /logs/ without JSON content-type."""
+    resp = client.post("/logs/", data="not json", headers={"Content-Type": "text/plain"})
+    assert resp.status_code in (400, 415, 422), f"Unexpected status: {resp.status_code}"
+
+
+def test_get_logs_invalid_limit():
+    """Test GET /logs/ with a negative limit returns 422 or handles gracefully."""
+    resp = client.get("/logs/?limit=-1")
+    assert resp.status_code in (200, 422), f"Unexpected status: {resp.status_code}"
+
+
+def test_get_logs_invalid_skip_type():
+    """Test GET /logs/ with non-integer skip returns 422."""
+    resp = client.get("/logs/?skip=abc")
+    assert resp.status_code == 422, f"Expected 422, got {resp.status_code}"