> ## 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/PSDSCUseIdenticalMandatoryParametersForDSC

> Use identical mandatory parameters for DSC Get/Test/Set TargetResource functions

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

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

<Note>
  tally disables this rule by default because Desired State Configuration resources are out
  of scope for Dockerfile `RUN` analysis. Re-enable it with
  `include = ["powershell/PSDSCUseIdenticalMandatoryParametersForDSC"]` or by setting
  `rules.powershell.PSDSCUseIdenticalMandatoryParametersForDSC.severity = "warning"` in `.tally.toml`.
</Note>

## Description

For script-based DSC resources, if a property is declared with attributes `Key` or `Required` in a
MOF file, then it should be present as a mandatory parameter in the corresponding
`Get-TargetResource`, `Set-TargetResource` and `Test-TargetResource` functions.

## How

Make sure all the properties with `Key` or `Required` attributes have equivalent mandatory
parameters in the `Get/Set/Test` functions.

## Examples

Consider the following `mof` file.

```powershell theme={null}
class WaitForAny : OMI_BaseResource
{
    [key, Description("Name of Resource on remote machine")]
    string Name;

    [required, Description("List of remote machines")]
    string NodeName[];
};
```

### Problematic code

```powershell theme={null}
function Get-TargetResource
{
    [CmdletBinding()]
    param
    (
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [String]
        $Message
    )
}

function Set-TargetResource
{
    [CmdletBinding()]
    param
    (
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [String]
        $Message,

        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [String]
        $Name
    )
}

function Test-TargetResource
{
    [CmdletBinding()]
    param
    (
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [String]
        $Message,

        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [String]
        $Name
    )
}
```

### Correct code

```powershell theme={null}
function Get-TargetResource
{
    [CmdletBinding()]
    param
    (
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [String]
        $Message,

        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [String]
        $Name
    )
}

function Set-TargetResource
{
    [CmdletBinding()]
    param
    (
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [String]
        $Message,

        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [String]
        $Name
    )
}

function Test-TargetResource
{
    [CmdletBinding()]
    param
    (
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [String]
        $Message,

        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [String]
        $Name
    )
}
```

## Source

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