如何用纠缠嘲笑

Question

I want to mock the results from Get-ChildItem but keep getting issues. How do I mock in Pester?

It 'Test get latest version' {
        Mock -CommandName 'Test-Path' –MockWith {
            return $true  
        }
        Mock -CommandName 'Get-ChildItem' –MockWith {
            $MockedListOfDirectories = `
            'test_1.0.1.1', `
            'test_1.1.10.5', `
            'test_1.1.10.1', `
            'test_1.2.18.1', `
            'test_1.4.7.0'
        return $MockedListOfDirectories
    }
            
}

The output from the tests:

PSInvalidCastException: Cannot convert the "â€MockWith {
             return True
         }
         Mock -CommandName 'Get-ChildItem' â€MockWith" value of type "System.String" to type "System.Management.Automation.ScriptBlock".
 ArgumentTransformationMetadataException: 
Cannot convert the "â€MockWith {
             return True
         }
         Mock -CommandName 'Get-ChildItem' â€MockWith" value of type "System.String" to type "System.Management.Automation.ScriptBlock".
 ParameterBindingArgumentTransformationException: Cannot process argument transformation on parameter 'MockWith'. Cannot convert the "â€MockWith {
             return True
         }
         Mock -CommandName 'Get-ChildItem' â€MockWith" value of type "System.String" to type "System.Management.Automation.ScriptBlock".
 at <ScriptBlock>, C:\my\path\to\file.ps1:8

Answer 1

It looks like the error you are seeing is because -MockWith is using an em-dash instead of a dash. This can happen sometimes if you've copied an example from a webpage.

Ensuring the dashes are non em-dash and your code works fine for me, although for it to be a complete test you need to actually do some testing that then invokes your Mocks, for example:

Describe 'tests' {

    It 'Test get latest version' {

        Mock -CommandName 'Test-Path' -MockWith {
            return $true  
        }

        Mock -CommandName 'Get-ChildItem' -MockWith {
            $MockedListOfDirectories = `
                'test_1.0.1.1', `
                'test_1.1.10.5', `
                'test_1.1.10.1', `
                'test_1.2.18.1', `
                'test_1.4.7.0'
            return $MockedListOfDirectories
        }

        Test-Path -Path 'fakepath' | Should -Be $true
     
        Get-ChildItem | Should -Contain 'test_1.1.10.5'
    }
}