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

# powershell/PSUseOutputTypeCorrectly

> Use OutputType Correctly

`powershell/PSUseOutputTypeCorrectly` is a PSScriptAnalyzer diagnostic emitted by tally for PowerShell snippets embedded in Dockerfiles.

| Property | Value             |
| -------- | ----------------- |
| Severity | Information       |
| Category | PSScriptAnalyzer  |
| Default  | Disabled in tally |
| Auto-fix | No                |

<Note>
  tally disables this rule by default for Dockerfile `RUN` snippets because a `RUN` executes
  statements inline rather than defining cmdlets, parameters, or modules with external callers. Re-enable it with
  `include = ["powershell/PSUseOutputTypeCorrectly"]` or by setting
  `rules.powershell.PSUseOutputTypeCorrectly.severity = "warning"` in `.tally.toml`.
</Note>

## Description

A command should return the same type as declared in `OutputType`.

You can get more details by running `Get-Help about_Functions_OutputTypeAttribute` command in
PowerShell.

## How

Specify that the OutputType attribute lists and the types returned in the cmdlet match.

## Examples

### Problematic code

```powershell theme={null}
function Get-Foo
{
        [CmdletBinding()]
        [OutputType([String])]
        Param(
        )
        return 4
}
```

### Correct code

```powershell theme={null}
function Get-Foo
{
        [CmdletBinding()]
        [OutputType([String])]
        Param(
        )

        return 'four'
}
```

## Source

This rule documentation is adapted from Microsoft's PSScriptAnalyzer documentation for
[UseOutputTypeCorrectly](https://github.com/MicrosoftDocs/PowerShell-Docs-Modules/blob/main/reference/docs-conceptual/PSScriptAnalyzer/Rules/UseOutputTypeCorrectly.md),
licensed under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/).