Pester Unit Test for Get-AzureBlobStorage-CodePudding

I am trying to write a unit for a simple Azure function in Powershell

function Get-AzureBlobStorage {
    param (
        [Parameter(Mandatory)]
        [string]$ContainerName,
        [Parameter(Mandatory)]
        [string]$Blob,
        [Parameter(Mandatory)]
        $Context
    )
    try {
        return (Get-AzStorageBlob -Container $ContainerName -Context $Context -Blob $Blob)
    }
    catch {
        Write-Error "Blobs in Container [$ContainerName] not found"

    }

Unit test

   Context 'Get-AzureBlobStorage' {
        It 'Should be able to get details to Blob Storage account without any errors' {
                $ContainerName = 'test'
                $Blob="test-rg"
                $Context = "test"
                Mock Get-AzStorageBlob { } -ModuleName $moduleName
                Get-AzureBlobStorage -ContainerName $ContainerName -Blob $Blob -Context $Context -ErrorAction SilentlyContinue -ErrorVariable errors
                $errors.Count | Should -Be 0
            }
}

But i was not able to get it to work. I am getting ht following error,

Cannot process argument transformation on parameter 'Context'. Cannot convert the "test" value of type "System.String" to type "Microsoft.Azure.Commands.Common.Authentication.Abstractions.IStorageContext".

My question is how to get such values as context. I have several other functions where one of the parameters is always some complex object. What is the best way to write unit test for such functions

CodePudding user response：

Your issue is because the input of the Get-AzStorageBlob cmdlet expects a specific type of object for -Context. You can get Pester to remove the strong type on the input by using Mock with -RemoveParameterType.

Here's how I'd test your function:

Describe 'Tests' {

    Context 'Get-AzureBlobStorage returns blob' {
        
        BeforeAll {
            Mock Get-AzStorageBlob {} -RemoveParameterType Context
        }

        It 'Should be able to get details to Blob Storage account without any errors' {

            $ContainerName = 'test'
            $Blob = "test-rg"
            $Context = "test"

            Get-AzureBlobStorage -ContainerName $ContainerName -Blob $Blob -Context $Context -ErrorVariable errors
            Assert-MockCalled Get-AzStorageBlob
        }
    }

    Context 'Get-AzureBlobStorage returns error' {

        BeforeAll {
            Mock Get-AzStorageBlob { throw 'Error' } -RemoveParameterType Context
            Mock Write-Error { }
        }

        It 'Should return an error via Write-Error' {

            $ContainerName = 'test'
            $Blob = "test-rg"
            $Context = "test"

            Get-AzureBlobStorage -ContainerName $ContainerName -Blob $Blob -Context $Context
            Assert-MockCalled Write-Error -Times 1 -Exactly
        }
    }
}