Automation with Lua

Lua Scripting transforms Solo from a simple HTTP client into an automation tool. Using Lua allows you to manipulate requests before sending and validate responses in real-time.

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Scripting Phases

In Solo, logic can be inserted at two points in a request’s lifecycle:

1. Pre-request Script (Before Sending)

This section is dedicated to data preparation. You can calculate dynamic security signatures (HMAC, SHA256), add custom headers based on the current time, or generate unique IDs (UUID) for transaction tracking.

2. Post-response Script (After Response)

This section is intended for analyzing results. You can extract tokens or IDs from the response, run assertion tests (e.g., verifying a 200 status), or log messages to the console for debugging.

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Session Variables

Session Variables allow communication between requests. Unlike environment variables, which are static and saved to disk, session variables reside exclusively in Solo’s memory and are populated dynamically during testing.

How to Use

Extracting a value via env.set("my_token", value) in one request allows it to be used as {{my_token}} in any other tab or request in the collection.

Instant Update

Any change to a session variable via script results in an automatic UI update. The new value is visible in tooltips and autocompletions without needing a reload.

Viewing and Management

You can monitor the session state directly in the builder:

1. Access the “Scripts” tab.
2. Consult the “Session Vars” list in the editor sidebar.
   
3. Reset the session using the “Clear” button next to the header.

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Native Libraries Included

Solo extends Lua with modules dedicated to common API operations:

Module	Functionality	Example
env	Variable management and logs.	env.set("key", "val"), env.log("msg")
json	JSON parsing and generation.	data = json.parse(response.body)
crypto	Hashing and encoding.	hash = crypto.sha256("test"), crypto.base64_encode("...")
uuid	Unique identifiers.	id = uuid.v4()
time	Time and date management.	now = time.now()

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Example: Extracting a Token

Example of a Post-response script for saving an access token:

-- 1. Convert response body to a Lua object
local data = json.parse(response.body)

-- 2. Extract the token from the "access_token" field
local token = data.access_token

-- 3. Save to Solo's session variables
if token then
    env.set("auth_token", token)
    env.log("Token saved successfully!")
else
    env.log("Error: token not found in response")
end

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Security and Performance

Loop Protection

To prevent local computer lockups caused by erroneous scripts, Solo automatically terminates scripts that run longer than 500ms or consume excessive memory.

Isolation

Lua scripts in Solo do not have access to the operating system files or the external network, beyond the current request. The testing environment remains safe and isolated.