> For the complete documentation index, see [llms.txt](https://as-pect.gitbook.io/as-pect/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://as-pect.gitbook.io/as-pect/docs/reference/assertion-reference.md).

# Assertion reference

This page summarizes the AssemblyScript test API from `@as-pect/assembly`.

## Test declarations

```ts
describe(description: string, callback: () => void): void;
it(description: string, callback: () => void): void;
test(description: string, callback: () => void): void;
xit(description: string, callback: () => void): void;
xtest(description: string, callback: () => void): void;
throws(description: string, callback: () => void, message?: string): void;
itThrows(description: string, callback: () => void, message?: string): void;
todo(description: string): void;
```

## Hooks

```ts
beforeEach(callback: () => void): void;
beforeAll(callback: () => void): void;
afterEach(callback: () => void): void;
afterAll(callback: () => void): void;
```

## Expectations

```ts
expect<T>(actual: T | null): Expectation<T>;
expectFn(cb: () => void): Expectation<() => void>;
```

## `Expectation<T>` methods

| Method                     | Signature                                                                  |
| -------------------------- | -------------------------------------------------------------------------- |
| Strict equality            | \`toBe(expected: T                                                         |
| Strict/reference equality  | \`toStrictEqual(expected: T                                                |
| Block equality             | \`toBlockEqual(expected: T                                                 |
| Function throws            | `toThrow(message?: string): void`                                          |
| Function throws with text  | `toThrowWith(expectedMessage: string, message?: string): void`             |
| Truthy                     | `toBeTruthy(message?: string): void`                                       |
| Null                       | `toBeNull(message?: string): void`                                         |
| Falsy                      | `toBeFalsy(message?: string): void`                                        |
| Greater than               | \`toBeGreaterThan(expected: T                                              |
| Less than                  | \`toBeLessThan(expected: T                                                 |
| Greater than or equal      | \`toBeGreaterThanOrEqual(expected: T                                       |
| Less than or equal         | \`toBeLessThanOrEqual(expected: T                                          |
| Close floating-point value | `toBeCloseTo(expected: T, decimalPlaces?: number, message?: string): void` |
| NaN                        | `toBeNaN(message?: string): void`                                          |
| Finite                     | `toBeFinite(message?: string): void`                                       |
| Length                     | `toHaveLength(expected: i32, message?: string): void`                      |
| Includes                   | \`toInclude\<U extends valueof                                             |
| Contains alias             | `toContain(expected: valueof<T>, message?: string): void`                  |
| Includes equal             | \`toIncludeEqual\<U extends indexof                                        |
| Contains equal alias       | \`toContainEqual\<U extends indexof                                        |
| Snapshot                   | \`toMatchSnapshot(name?: string                                            |

## Negation

```ts
expect<i32>(42).not.toBe(0);
```

`not` returns the same expectation with negation applied.

## Logging and debugging

```ts
log<T>(value: T | null): void;
debug(): void;
```

Use `log` for values you want visible in reporter output.

## Related pages

* [Writing tests](/as-pect/docs/using/writing-tests.md)
* [Snapshots](/as-pect/docs/using/snapshots.md)
* [`@as-pect/assembly` types](/as-pect/docs/types/assembly.md)

***

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