Migrate to Pester 5

[Clijsters]

Current behaviour:

Build fails, because the whole testing setup is made for Pester <4.9.x, and the Install-Script for AppVeyor installs the latest Pester-version (5.0.x)

Error:

----               
C:\projects\pstoggl
. .\AppVeyor\Test.ps1
Current working directory: C:\projects\pstoggl
You are using Legacy parameter set that adapts Pester 5 syntax to Pester 4 syntax. This parameter set is deprecated, and does not work 100%. The -Strict and -PesterOption parameters are ignored, and providing advanced configuration to -Path (-Script), and -CodeCoverage via a hash table does not work. Please refer to https://github.com/pester/Pester/releases/tag/5.0.1#legacy-parameter-set for more information.
Starting discovery in 20 files.
Discovery finished in 4.64s.
[-] General code style compliance.Module 'C:\projects\pstoggl\.codecovio\CodeCovIo.psm1'.passes the PSScriptAnalyzer Rule PSAlignAssignmentStatement 247ms (110ms|137ms)
 ValidationMetadataException: The argument is null. Provide a valid value for the argument, and then try running the command again.
 ParameterBindingValidationException: Cannot validate argument on parameter 'Path'. The argument is null. Provide a valid value for the argument, and then try running the command again.
 at <ScriptBlock>, C:\projects\pstoggl\PSToggl\PSToggl.Tests.ps1:15
[-] General code style compliance.Module 'C:\projects\pstoggl\.codecovio\CodeCovIo.psm1'.passes the PSScriptAnalyzer Rule PSAvoidUsingCmdletAliases 12ms (9ms|3ms)
 ValidationMetadataException: The argument is null. Provide a valid value for the argument, and then try running the command again.
 ParameterBindingValidationException: Cannot validate argument on parameter 'Path'. The argument is null. Provide a valid value for the argument, and then try running the command again.
 at <ScriptBlock>, C:\projects\pstoggl\PSToggl\PSToggl.Tests.ps1:15

And

Should : Legacy Should syntax (without dashes) is not supported in Pester 5. Please refer to migration guide at: https://pester.dev/docs/migrations/v3-to-v4
At C:\projects\pstoggl\Tests\PSToggl\Private\ConvertTo-TogglTask.Tests.ps1:40 char:37
+                 {$out.ToString()} | Should Not Throw
+                                     ~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [Write-Error], WriteErrorException
    + FullyQualifiedErrorId : Microsoft.PowerShell.Commands.WriteErrorException,Should

Solution

Migrate to Pester 5.x

This basically involves:

• Changing invocation in AppVeyor/Test.ps1
• Remove version parameter from Install-Module in AppVeyor/Install.ps1
• Assert-MockCalled should be replaced with Should -Invoke
• You might want to take a look at the migration guide.

Quickfix until then:
Fix version to <=4.9.9 in AppVeyor/Install.ps1

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Possible improvements:

While the coverage is overall quite ok, there is room for improvement for test structure in general.