> ## Documentation Index
> Fetch the complete documentation index at: https://docs.requestly.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Expect Object (rq.expect)

> Complete reference for the rq.expect object in Requestly scripts to write assertions for API testing using Chai.js assertion library.

The `rq.expect` object provides assertion methods for writing tests in Requestly. It is built on top of the popular [Chai.js](https://www.chaijs.com/) assertion library, giving you access to powerful and expressive assertions for validating API responses.

<Note>
  **Using Chai.js**: Requestly uses the Chai.js BDD assertion library. For the complete list of assertions and advanced features, refer to the [Chai.js official documentation](https://www.chaijs.com/api/bdd/).
</Note>

## Basic Usage

The `rq.expect` function is used within test functions created by `rq.test` to assert expected conditions:

```jsx theme={null}
rq.test("Status code is 200", function() {
    rq.expect(rq.response.code).to.equal(200);
});
```

## Common Assertions

Below are some commonly used Chai.js assertions. For a complete reference, visit the [Chai.js BDD API documentation](https://www.chaijs.com/api/bdd/).

### Equality

```jsx theme={null}
rq.expect(value).to.equal(expected);        // Strict equality (===)
rq.expect(obj).to.eql(expected);            // Deep equality
rq.expect(value).to.deep.equal(expected);   // Deep equality (alias)
```

### Type Checking

```jsx theme={null}
rq.expect(value).to.be.a("string");
rq.expect(value).to.be.an("array");
rq.expect(value).to.be.a("number");
rq.expect(value).to.be.a("boolean");
```

### Properties

```jsx theme={null}
rq.expect(obj).to.have.property("key");
rq.expect(obj).to.have.property("key", value);
```

### Strings

```jsx theme={null}
rq.expect(str).to.include("substring");
rq.expect(str).to.match(/regex/);
```

### Numbers

```jsx theme={null}
rq.expect(num).to.be.above(value);
rq.expect(num).to.be.below(value);
rq.expect(num).to.be.within(min, max);
```

### Arrays & Length

```jsx theme={null}
rq.expect(arr).to.have.lengthOf(value);
rq.expect(arr).to.include(item);
rq.expect(arr).to.be.empty;
```

### Booleans & Existence

```jsx theme={null}
rq.expect(value).to.be.true;
rq.expect(value).to.be.false;
rq.expect(value).to.exist;
rq.expect(value).to.be.null;
rq.expect(value).to.be.undefined;
```

## Negation with `.not`

Negate any assertion using `.not`:

```jsx theme={null}
rq.expect(value).to.not.equal("deleted");
rq.expect(arr).to.not.be.empty;
```

## Chaining Assertions

Chain multiple assertions for better readability:

```jsx theme={null}
rq.expect(data.id).to.be.a("number").and.to.be.above(0);
rq.expect(data.name).to.be.a("string").that.is.not.empty;
```

## Example: Validate Response Structure

```jsx theme={null}
rq.test("Response has correct structure", function() {
    const data = rq.response.json();
    
    rq.expect(data).to.be.an("object");
    rq.expect(data).to.have.property("status");
    rq.expect(data).to.have.property("data");
    rq.expect(data.data).to.be.an("array").and.not.be.empty;
});
```

## More Assertions

For the complete list of assertions including:

* Advanced object and array matchers
* Custom assertions with `.satisfy()`
* Key checking with `.have.keys()`
* And many more...

Visit the **[Chai.js BDD API Documentation](https://www.chaijs.com/api/bdd/)**

## Related Documentation

* [Pre-request & Post-response Scripts](/api-client/scripts)
* [rq.test Object](/api-client/rq-api-reference/rq-test)
* [rq.response Object](/api-client/rq-api-reference/rq-response)
* [Tests Documentation](/api-client/tests)
* [Chai.js Official Documentation](https://www.chaijs.com/api/bdd/) - For complete assertion reference