public/Assert.ps1
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function Assert { <# .SYNOPSIS Helper function for "Design by Contract" assertion checking. .DESCRIPTION This is a helper function that makes the code less noisy by eliminating many of the "if" statements that are normally required to verify assumptions in the code. .PARAMETER ConditionToCheck The boolean condition to evaluate .PARAMETER FailureMessage The error message used for the exception if the ConditionToCheck parameter is false .EXAMPLE C:\PS>Assert $false "This always throws an exception" Example of an assertion that will always fail. .EXAMPLE C:\PS>Assert ( ($i % 2) -eq 0 ) "$i is not an even number" This exmaple may throw an exception if $i is not an even number Note: It might be necessary to wrap the condition with paranthesis to force PS to evaluate the condition so that a boolean value is calculated and passed into the 'ConditionToCheck' parameter. Example: Assert 1 -eq 2 "1 doesn't equal 2" PS will pass 1 into the condtionToCheck variable and PS will look for a parameter called "eq" and throw an exception with the following message "A parameter cannot be found that matches parameter name 'eq'" The solution is to wrap the condition in () so that PS will evaluate it first. Assert (1 -eq 2) "1 doesn't equal 2" .LINK Exec .LINK FormatTaskName .LINK Framework .LINK Get-PSakeScriptTasks .LINK Include .LINK Invoke-psake .LINK Properties .LINK Task .LINK TaskSetup .LINK TaskTearDown #> [CmdletBinding()] param( [Parameter(Mandatory = $true)] $ConditionToCheck, [Parameter(Mandatory = $true)] [string]$FailureMessage ) if (-not $ConditionToCheck) { throw ('Assert: {0}' -f $FailureMessage) } } |