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Add -Shuffle switch to Get-Random command #11093

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Merged
adityapatwardhan merged 3 commits into from
Apr 15, 2020
Merged

Add -Shuffle switch to Get-Random command #11093

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830ed3d
Add `-Shuffle` switch to Get-Random command
eugenesmlv Nov 17, 2019
ce35e20
Fix CodeFactor issue
eugenesmlv Nov 17, 2019
fe68cf6
Fix the review issues
eugenesmlv Nov 18, 2019
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58 changes: 41 additions & 17 deletions src/Microsoft.PowerShell.Commands.Utility/commands/utility/GetRandomCommand.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@ public class GetRandomCommand : PSCmdlet

private const string RandomNumberParameterSet = "RandomNumberParameterSet";
private const string RandomListItemParameterSet = "RandomListItemParameterSet";
private const string ShuffleParameterSet = "ShuffleParameterSet";
private static readonly object[] _nullInArray = new object[] { null };

private enum MyParameterSet
Expand All @@ -50,7 +51,8 @@ private MyParameterSet EffectiveParameterSet
{
_effectiveParameterSet = MyParameterSet.RandomListItem;
}
else if (ParameterSetName.Equals(GetRandomCommand.RandomListItemParameterSet, StringComparison.OrdinalIgnoreCase))
else if (ParameterSetName == GetRandomCommand.RandomListItemParameterSet
|| ParameterSetName == GetRandomCommand.ShuffleParameterSet)
{
_effectiveParameterSet = MyParameterSet.RandomListItem;
}
Expand Down Expand Up @@ -276,19 +278,31 @@ private double ConvertToDouble(object o, double defaultIfNull)
/// List from which random elements are chosen.
/// </summary>
[Parameter(ParameterSetName = RandomListItemParameterSet, ValueFromPipeline = true, Position = 0, Mandatory = true)]
[Parameter(ParameterSetName = ShuffleParameterSet, ValueFromPipeline = true, Position = 0, Mandatory = true)]
[System.Management.Automation.AllowNull]
[SuppressMessage("Microsoft.Performance", "CA1819:PropertiesShouldNotReturnArrays")]
public object[] InputObject { get; set; }

/// <summary>
/// Number of items to output (number of list items or of numbers).
/// </summary>
[Parameter]
[Parameter(ParameterSetName = RandomNumberParameterSet)]
[Parameter(ParameterSetName = RandomListItemParameterSet)]
[ValidateRange(1, int.MaxValue)]
public int Count { get; set; } = 1;

#endregion

#region Shuffle parameter

/// <summary>
/// Gets or sets whether the command should return all input objects in randomized order.
/// </summary>
[Parameter(ParameterSetName = ShuffleParameterSet, Mandatory = true)]
public SwitchParameter Shuffle { get; set; }

#endregion

#region Cmdlet processing methods

private double GetRandomDouble(double minValue, double maxValue)
Expand Down Expand Up @@ -492,29 +506,39 @@ protected override void ProcessRecord()
{
if (EffectiveParameterSet == MyParameterSet.RandomListItem)
{
// this allows for $null to be in an array passed to InputObject
foreach (object item in InputObject ?? _nullInArray)
if (ParameterSetName == ShuffleParameterSet)
{
// (3)
if (_numberOfProcessedListItems < Count)
// this allows for $null to be in an array passed to InputObject
foreach (object item in InputObject ?? _nullInArray)
{
Debug.Assert(_chosenListItems.Count == _numberOfProcessedListItems, "Initial K elements should all be included in chosenListItems");
_chosenListItems.Add(item);
}
else
}
else
{
foreach (object item in InputObject ?? _nullInArray)
{
Debug.Assert(_chosenListItems.Count == Count, "After processing K initial elements, the length of chosenItems should stay equal to K");

// (1)
if (Generator.Next(_numberOfProcessedListItems + 1) < Count)
// (3)
if (_numberOfProcessedListItems < Count)
{
// (2)
int indexToReplace = Generator.Next(_chosenListItems.Count);
_chosenListItems[indexToReplace] = item;
Debug.Assert(_chosenListItems.Count == _numberOfProcessedListItems, "Initial K elements should all be included in chosenListItems");
_chosenListItems.Add(item);
}
else
{
Debug.Assert(_chosenListItems.Count == Count, "After processing K initial elements, the length of chosenItems should stay equal to K");

// (1)
if (Generator.Next(_numberOfProcessedListItems + 1) < Count)
{
// (2)
int indexToReplace = Generator.Next(_chosenListItems.Count);
_chosenListItems[indexToReplace] = item;
}
}
}

_numberOfProcessedListItems++;
_numberOfProcessedListItems++;
}
}
}
}
Expand Down
8 changes: 7 additions & 1 deletion test/powershell/Modules/Microsoft.PowerShell.Utility/Get-Random.Tests.ps1
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Original file line number Diff line number Diff line change
Expand Up @@ -156,6 +156,12 @@ Describe "Get-Random" -Tags "CI" {
$randomNumber[6] | Should -BeNullOrEmpty
}

It "Should return all the numbers for array of 1,2,3,5,8,13 in randomized order when the Shuffle switch is used" {
$randomNumber = Get-Random -InputObject 1, 2, 3, 5, 8, 13 -Shuffle
$randomNumber.Count | Should -Be 6
$randomNumber | Should -BeIn 1, 2, 3, 5, 8, 13
}

It "Should return for a string collection " {
$randomNumber = Get-Random -InputObject "red", "yellow", "blue"
$randomNumber | Should -Be ("red" -or "yellow" -or "blue")
Expand All @@ -173,7 +179,7 @@ Describe "Get-Random" -Tags "CI" {
$firstRandomNumber | Should -Not -Be $secondRandomNumber
}

It "Should return the same number for hexadecimal number and regular number when the switch SetSeed it used " {
It "Should return the same number for hexadecimal number and regular number when the switch SetSeed is used " {
$firstRandomNumber = Get-Random 0x07FFFFFFFF -SetSeed 20
$secondRandomNumber = Get-Random 34359738367 -SetSeed 20
$firstRandomNumber | Should -Be @secondRandomNumber
Expand Down