Assert-Empty.ps1
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# Copyright 2012 - 2015 Aaron Jensen # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. function Assert-Empty { <# .SYNOPSIS Checks that an object is empty. .DESCRIPTION This checks that an object's `Length` or `Count` property is equal to 0. That means this function should be used with strings or collections, or similar objects. .EXAMPLE Assert-Empty '' Demonstrates how to check if a string is empty, which in this case it is. .EXAMPLE Assert-Empty @() Demonstrates that collections can be checked as well as strings. .EXAMPLE Assert-Empty @{ Foo = 'Bar' } 'Settings not initialized.' Demonstrates how to show your own message when the assertion fails. #> [CmdletBinding()] param( [Parameter(Position=0)] [object] # The object to check. $InputObject, [Parameter(Position=1)] [string] # A descriptive message to show if the object isn't empty. $Message ) Set-StrictMode -Version 'Latest' if( $InputObject -eq $null ) { Fail ("Object is null but expected it to be empty. {0}" -f $Message) return } $hasLength = Get-Member -InputObject $InputObject -Name 'Length' $hasCount = Get-Member -InputObject $InputObject -Name 'Count' if( -not $hasLength -and -not $hasCount ) { Fail ("Object '{0}' has no Length/Count property, so can't determine if it's empty. {1}" -f $InputObject,$Message) } if( ($hasLength -and $InputObject.Length -ne 0) -or ($hasCount -and $InputObject.Count -ne 0) ) { Fail ("Object '{0}' not empty. {1}" -f $InputObject,$Message) } } |