> ## Documentation Index
> Fetch the complete documentation index at: https://starkware-9575960b-chore-starknet-docs-url-migration.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# core::starknet::testing::cheatcode

A general cheatcode function used to simplify implementation of Starknet testing functions.
This is the base function used by testing utilities to interact with the test
environment. External users can implement custom cheatcodes by injecting a custom
`CairoHintProcessor` in the runner.

## Signature

```rust theme={null}
pub extern fn cheatcode(input: Span) -> Span nopanic;
```

#### Arguments

`selector` - The cheatcode identifier.
`input` - Input parameters for the cheatcode.

#### Returns

* A span containing the cheatcode's output