Web Socket step

The WebSocket step enables real-time, bidirectional communication testing by allowing you to connect to WebSocket endpoints, send messages, and validate responses. This step is particularly useful for testing applications that require persistent connections and real-time data exchange.

WebSocket Step Operations

A WebSocket step can perform three main operations:

1. Connect - Establishes a WebSocket connection to the specified endpoint

2. Send - Transmits messages through an established WebSocket connection

3. Receive - Listens for and validates incoming WebSocket messages

Step Configuration

Connection

When establishing a connection:

• The URL format follows: wss://<your-websocket-endpoint>

• Headers can be added to the WebSocket handshake request for authentication or custom protocols

• A timeout value (in seconds) can be set for the connection attempt

Sending Messages

For sending messages:

• Supports two data types:

  • Text (JSON, plain text)

  • Binary data

• Messages can include dynamic parameters

• Headers can be included with the message

• Used for both sending data and subscribing to channels

• A timeout can be specified for the send operation

Note: A Send step without a preceding Connect step will automatically create a new WebSocket connection.

Receiving Messages

When receiving messages:

• Messages are fetched based on the WebSocket URL

  • Use URL query parameters (e.g., wss://example.com/ws?userId=1) to send and filter messages by specific properties

• Message retrieval options:

  • Last - Returns the most recent single message

  • Last 10 - Returns an array of the last 10 messages

  • Last 50 - Returns an array of the last 50 messages

• Extractions support all standard Loadmill extraction methods

  • Example JSONPath for array filtering: $[?(@.id == "${my_id}")]

  • Learn more about extractions

• Wait for extractions to be resolved - Since WebSocket connections are asynchronous, this setting defines how long to wait for messages that match your extraction criteria. Default is 5 seconds, but you may need to adjust this based on your application's behavior.

• Assertions - Use the same powerful assertion capabilities as HTTP requests to validate your WebSocket messages, including JSON/XML validation, value comparisons, and regex matching. Learn more about assertions

• The Flow Control section allows to repeat the request until the parameter's value meets the requirement or number of iteration reached.

Example Run

Let's look at a simple WebSocket test flow in action:

This example demonstrates a complete WebSocket interaction:

1. Connect to WebSocket:

• Establishes connection to a WebSocket server

2. Send Some Data:

• Sends a message on the connection

3. Assert message received:

• Waits for all extractions to be resolved

• Once resolved, validates that the extracted ${message} exists

• Received messages are displayed for easy debugging