Console Assertions - LambdaTest

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Console assertions let you verify browser console output: error messages, warnings, log messages, and uncaught JavaScript exceptions.

How Capture Works

KaneAI captures all browser console output automatically during each test step:

Continuous capture: Every console.log(), console.warn(), console.error(), and uncaught JS exception is recorded
Per-step scope: Each test step starts with a fresh capture. Console messages from previous steps are not carried over
Limits: Up to 50,000 messages are stored per step. When the limit is reached, the oldest 10% are dropped
No truncation: Message text is stored in full. Unlike network response bodies, console messages are never truncated
Object resolution: When JavaScript logs an object (console.log({status: "ok"})), KaneAI resolves it to the actual value instead of storing “JSHandle@object”
Multi-tab support: Console messages from new tabs and popups are also captured
Top-frame only: Messages from embedded iframes (payment widgets, third-party components) are not captured

Planning for Multi-Step Tests

Because console data resets each step, plan accordingly:

If you need to verify a console message later, extract and store it in the same step it appears
Console output from step 1 won’t be visible in step 3’s console log

Level Normalization

Console message levels are normalized to 5 values:

Level	What triggers it
`log`	`console.log()`, `console.dir()`, `console.table()`, and other info-level calls
`warning`	`console.warn()`
`error`	`console.error()` and uncaught exceptions
`info`	`console.info()`
`debug`	`console.debug()`

What You Can Query

Field	Type	Description
`level`	string	Message level: “log”, “warning”, “error”, “info”, “debug”
`text`	string	Full message text (not truncated)
`url`	string	Source file URL
`line_number`	int	Source line number
`is_exception`	bool	True for uncaught JS exceptions (pageerror events)
`stack_trace`	string	Stack trace (exceptions only)

Errors vs Exceptions

errors includes ALL error-level messages: both console.error() calls AND uncaught exceptions
exceptions is a subset of errors: only uncaught JavaScript exceptions
To check for app-level errors without exceptions: query errors where is_exception is false

Example Assertions

Assert: no console errors on the page
Assert: no uncaught JavaScript exceptions
Assert: console contains "Amplitude SDK triggered"
Assert: no console warnings
Assert: no JS errors after clicking Submit

Example Extractions

Store all console error messages
Extract the first console error text
Store all console log output

Example If/Else

If console contains "feature_flag_enabled" then use new flow, else use legacy flow

​How Capture Works

​Planning for Multi-Step Tests

​Level Normalization

​What You Can Query

​Errors vs Exceptions

​Example Assertions

​Example Extractions

​Example If/Else