Create Test-IsBlank.ps1

Pwsh/Testing/examples/Test-IsBlank.ps1

@@ -0,0 +1,82 @@
+# First, the simple versions
+
+function IsNull {
+    # test for true null only. everything else is false
+    [OutputType('System.Boolean')]
+    param( $Object  )
+    $null -eq $Object
+}
+function IsEmptyStr {
+    # test for empty string only. everything else is false
+    [OutputType('System.Boolean')]
+    param( $Object  )
+    ($Object -is [string]) -and $Object.length -eq ''
+}
+function IsBlank {
+    [OutputType('System.Boolean')]
+    param( $Object )
+    [string]::IsNullOrWhiteSpace( $Object )
+}
+
+function Test-IsBlank {
+    <#
+    .synopsis
+        Checks if an object is a true null. starting to get fancy
+    .description
+        Creates a table of different kinds of blankness
+        - true null values
+        - true empty string
+        - strings with whitespace
+    #>
+    param(
+        $Obj,
+        # if true, the function returns a single boolean, no info
+        [switch]$AsBool
+    )
+    $filtered = $Obj -replace "`a", '' # otherwise ascii bell is not "whitespace"
+    if($AsBool) {
+       return [string]::IsNullOrWhiteSpace( $filtered )
+    }
+
+    $isTrueNull     = $Null -eq $Obj
+    $isStr          = $Obj -is [String]
+    $isTrueEmptyStr = $isStr -and ($Obj.Length -eq 0)
+
+    $finalLength = if(-not $IsTrueNull) { $Obj.ToString().Length }
+    if($isTrueEmptyStr) { $finalLength = '<EmptyStr>' }
+    if($IsTrueNull)     { $finalLength = '<null>'     }
+
+    [pscustomobject]@{
+        IsTrueNull     = $isTrueNull
+        IsEmpty        = [string]::IsNullOrEmpty( $Obj )
+        IsTrueEmptyStr = $isTrueEmptyStr
+        IsBlank        = [string]::IsNullOrWhiteSpace( $filtered )
+        Length         = $finalLength
+        RawValue       = $Obj
+        AsBool         = [string]::IsNullOrWhiteSpace( $filtered )
+    }
+}
+
+<#
+    $examples = $null, ' ' , ''
+    $examples | %{
+        IsNull $_
+    } | Join-String -sep ', ' -op 'IsNull:     '
+    
+    # output
+    # true, false, false
+    
+    $examples | %{
+        IsEmptyStr $_
+    } | Join-String -sep ', ' -op 'IsEmptyStr: '
+    
+    # output
+    # false, false, true
+    
+    $examples | %{
+        IsBlank $_
+    } | Join-String -sep ', ' -op 'IsBlank:    '
+    
+    # output
+    # true, true, true
+#>