---
title: testing.shouldError() function
description: testing.shouldError() calls a function that catches any error and checks that the error matches the expected value.
url: https://docs.influxdata.com/flux/v0/stdlib/testing/shoulderror/
estimated_tokens: 612
product: Flux
version: v0
---

# testing.shouldError() function

-   Flux 0.174.0+
-   View InfluxDB support

`testing.shouldError()` calls a function that catches any error and checks that the error matches the expected value.

##### Function type signature

```js
(fn: () => A, want: regexp) => stream[{v: string}]
```

For more information, see [Function type signatures](/flux/v0/function-type-signatures/).

## Parameters

### fn

(Required) Function to call.

### want

(Required) Regular expression to match the expected error.

## Examples

### Test die function errors

```js
import "testing"

testing.shouldError(fn: () => die(msg: "error message"), want: /error message/)
```

[tests](/flux/v0/tags/tests/)