New-CsvSampleData: PowerShell function for automated creation of sample CSV data

New-CsvSampleData.ps1

function New-CsvSampleData {
  <#
  .SYNOPSIS
  Generates CSV sample data.
  
  .DESCRIPTION
  Generates simple CSV sample data as either a single multiline string or
  an array of lines.
  
  For now, the data-row field values are simply constructed as:
    <columnName>Val<ndx>
  where <ndx> is a sequence number starting at 1.

  By default, 5 rows are generated; use -Count to modify.
  
  .PARAMETER Columns
  Either: 
    An array of explicit column names.
  Or:
    A single number indicating how many columns to generate in the form of
    "col<ndx>", where <ndx> is a 1-based sequence number; e.g., for 3:
    "col1","col2","col3"
    
  .PARAMETER Count
  The number of data rows to generate. Defaults to 5.
  
  .PARAMETER Delimiter
  The field delimiter (separator) to use; defaults to a comma.
  Only a single char. is supported.
  
  .PARAMETER Stream
  Request output as an array of rows (lines).
  By default, a single multiline string is output.
  
  .PARAMETER Newline
  The newline character [sequence] to use to separate output rows (applies only
  if -Stream is not specified).
  Defaults to the platform-native newline format.
  Pass a literal sequence to override, namely "`n" for Unix-style newlines, and
  "`r`n" for Windows-style newlines.
  
  .NOTES
  Requires PSv4+

  .EXAMPLE
  New-CsvSampleData 3 2

  Generates a 3-column CSV with auto-generated columns names with 2 rows of
  auto-generated values, which yields:

  "col1","col2","col3"
  "col1Val1","col2Val1","col3Val1"
  "col1Val2","col2Val2","col3Val2"

  .EXAMPLE
  New-CsvSampleData foo, bar, baz 3
  
  Generates a multiline CSV string with columns 'foo', 'bar', and 'baz' and 
  3 data rows, which yields:
  
  "foo","bar","baz"
  "fooVal1","barVal1","bazVal1"
  "fooVal2","barVal2","bazVal2"
  "fooVal3","barVal3","bazVal3"
  
  .EXAMPLE
  New-CsvSampleData Id, Name 100 -Stream | Select-Object -First 2
  
  Generates CSV rows that, due to -Stream, are sent through the pipeline
  one by one (a 2-element array of strings).
  
  "Id","Name"
  "IdVal1","NameVal1"
  
  #>  
    [CmdletBinding(PositionalBinding=$False)]
    param(
      [parameter(Mandatory, Position=0, HelpMessage='Enter the column names')]
      [string[]] $Columns
      ,
      [parameter(Position=1)]
      [ValidateRange(0, [int]::MaxValue)]
      [int] $Count = 5
      ,
      [Alias('Separator')]
      [char] $Delimiter = ',' # "delimiter" == separator: separates header and data-row values
      ,
      [switch] $Stream # output an array of lines rather than a single string
      ,
      [string] $Newline = [environment]::NewLine # n/a if -Stream is specified
    )
  
    # If only a single number was specified for -Columns, interpret it
    # as the number of columns to auto-generate as "col<ndx>".
    if ($Columns.Count -eq 1 -and ($numCols = $Columns[0] -as [int])) {
      $Columns = 1..$numCols -replace '^', 'col'
    }

    # Synthesize a data-row template in the form of <colName>Val<ndx> field values.
    $valTemplate = $(foreach ($col in $Columns) {  
            "`"${col}Val{0}`""
        }) -join $Delimiter
  
    $headerRow = '"{0}"' -f ($Columns -join "`"$Delimiter`"")
    $dataRows = $null
    if ($Count) {
      $dataRows = (1..$Count).ForEach({ $valTemplate -f $_ })
    }
  
    if ($Stream) {  # output an array of lines
      $headerRow
      $dataRows
    } else {  # output a single, multiline string.
      # Note: We do NOT append a trailing newline, because PowerShell's > / Out-File / Set-Content
      #       do that on outputting to a file by default.
      '{0}{1}{2}' -f $headerRow, ($Newline * ([bool] $dataRows)), ($dataRows -join $NewLine)
    }
  
}

# If this script is invoked directly - as opposed to being dot-sourced in order
# to define the embedded function for later use - invoke the embedded function,
# relaying any arguments passed.
if (-not ($MyInvocation.InvocationName -eq '.' -or $MyInvocation.Line -eq '')) {
  New-CsvSampleData @Args
}