Assertions Basics

Assertions are used to verify that your API is behaving as expected. In Restflow, you use the assert directive to check the status code, headers, and body of a response.

The assert Directive

The assert directive has the following structure:

> assert <source> <operator> <value>

• source: The part of the response to check (e.g., status, body.id, headers["content-type"]).
• operator: The comparison to perform (e.g., ==, !=, >, contains).
• value: The expected value.

If an assertion fails, the step is marked as failed, and the execution of the flow may stop depending on your configuration.

Common Assertions

Here are some of the most common assertions you'll use:

Checking the Status Code

This is the most fundamental assertion. You should almost always check the status code.

### Get a resource
GET https://api.example.com/items/1

> assert status == 200

Checking the Response Body

You can use JSONPath to access values in a JSON response body.

### Get a user
GET https://api.example.com/users/123

> assert body.id == 123
> assert body.name == "John Doe"
> assert body.address.city == "New York"

Checking for Existence

You can check if a field exists in the response.

> assert body.id != null

Checking Array Length

> assert body.items.length > 0

Checking Headers

> assert headers["content-type"] contains "application/json"

These are just the basics. The "DSL Reference" section has a complete guide to all the available assertion operators and advanced techniques.