How to Assert Network Traffic in Kane CLI

Network assertions let you verify HTTP traffic: API responses, status codes, headers, response bodies, and request timing.

Network assertions also cover API calls that you make directly in an objective, not only the requests the page makes on its own. The agent records its own calls, and you query them with the same fields listed below. To make a call, for example to seed data or call a backend, see API Calls.

How Capture Works

KaneAI captures all HTTP network traffic automatically during each test step:

Continuous capture: Every HTTP request and response is recorded as it happens
Per-step scope: Each test step starts with a fresh capture. Traffic from previous steps is not carried over
Limits: Up to 5,000 requests are stored per step. When the limit is reached, the oldest 10% of entries are dropped to make room. Response bodies are capped at 64KB per entry
Text bodies only: Response bodies are captured for text-based content types (JSON, HTML, XML, CSS, JavaScript). Binary content (images, fonts, videos) is skipped
Multi-tab support: Traffic from new tabs and popups is also captured

Planning for Multi-Step Tests

Network data resets at every step, so plan for it:

If you need to assert on an API response later, extract and store it in the same step the request happens
Navigation and API calls in step 1 won’t be visible in step 3’s network log
Use extraction checkpoints to save values across steps

What You Can Query

Field	Type	Description
`method`	string	HTTP method (GET, POST, PUT, DELETE, …)
`url`	string	Full request URL
`domain`	string	Domain (e.g., “api.example.com”)
`path`	string	URL path without query string
`query_params`	dict	Query parameters
`resource_type`	string	xhr, fetch, document, script, image, …
`request_headers`	dict	Request headers
`request_body`	string	Request body (may be truncated)
`response_status`	int	HTTP status code (200, 404, 500, …)
`response_headers`	dict	Response headers
`response_body`	string	Response body (text types only, may be truncated)
`timing.duration_ms`	float	Total request duration in milliseconds
`timing.ttfb_ms`	float	Time to first byte in milliseconds
`failed`	bool	True if request failed at network level
`failure_reason`	string	Error reason (e.g., “net::ERR_CONNECTION_REFUSED”)

Example Assertions

Assert: no API calls returned 5xx status codes
Assert: the POST /api/login returned HTTP status 200
Assert: all API responses completed in under 2 seconds
Assert: no network requests failed with connection errors
Assert: the /posts endpoint returned at least 10 items in the response body

Example Extractions

Store the response body of the POST /api/login request
Extract the status code of the last API call to /api/users
Store all API request URLs

Example If/Else

If the /api/auth returned 200 then proceed to dashboard, else show error message

WebSocket and SSE Capture (Experimental)

Kane CLI can also capture WebSocket and server-sent events (SSE) traffic. Turn it on with run --network-ws and run --network-sse. Both are off by default, and SSE capture works only in Chromium. To keep a setting across runs, use config set-network-ws on|off or config set-network-sse on|off. testmd run and testrun run do not accept these flags.

​How Capture Works

​Planning for Multi-Step Tests

​What You Can Query

​Example Assertions

​Example Extractions

​Example If/Else

​WebSocket and SSE Capture (Experimental)

How Capture Works

Planning for Multi-Step Tests

What You Can Query

Example Assertions

Example Extractions

Example If/Else

WebSocket and SSE Capture (Experimental)