PowerShell · daxian-dbw · Jun 19, 2023 · Nov 6, 2022 · Mar 1, 2023 · Mar 1, 2023
diff --git a/src/Microsoft.PowerShell.Commands.Utility/commands/utility/WriteProgressCmdlet.cs b/src/Microsoft.PowerShell.Commands.Utility/commands/utility/WriteProgressCmdlet.cs
@@ -17,7 +17,6 @@ public sealed class WriteProgressCommand : PSCmdlet
         /// </summary>
         [Parameter(
             Position = 0,
-            Mandatory = true,
             HelpMessageBaseName = HelpMessageBaseName,
             HelpMessageResourceId = "ActivityParameterHelpMessage")]
         public string Activity { get; set; }
@@ -96,7 +95,29 @@ protected override
         void
         ProcessRecord()
         {
-            ProgressRecord pr = new(Id, Activity, Status);
+            ProgressRecord pr;
+            if (string.IsNullOrEmpty(Activity))
+            {
+                if (!Completed)
+                {
+                    ThrowTerminatingError(new ErrorRecord(
+                    new ArgumentException("Missing value for mandatory parameter.", nameof(Activity)),
+                    "MissingActivity",
+                    ErrorCategory.InvalidArgument,
+                    Activity));
+                    return;
+                }
+                else
+                {
+                    pr = new(Id);
+                    pr.StatusDescription = Status;
+                }
+            }
+            else
+            {
+                pr = new(Id, Activity, Status);
+            }
+
             pr.ParentActivityId = ParentId;
             pr.PercentComplete = PercentComplete;
             pr.SecondsRemaining = SecondsRemaining;

diff --git a/src/System.Management.Automation/engine/ProgressRecord.cs b/src/System.Management.Automation/engine/ProgressRecord.cs
@@ -59,6 +59,25 @@ class ProgressRecord
             this.status = statusDescription;
         }
 
+        /// <summary>
+        /// Initializes a new instance of the ProgressRecord class and defines the activity Id.
+        /// </summary>
+        /// <param name="activityId">
+        /// A unique numeric key that identifies the activity to which this record applies.
+        /// </param>
+        public
+        ProgressRecord(int activityId)
+        {
+            if (activityId < 0)
+            {
+                // negative Ids are reserved to indicate "no id" for parent Ids.
+
+                throw PSTraceSource.NewArgumentOutOfRangeException(nameof(activityId), activityId, ProgressRecordStrings.ArgMayNotBeNegative, "activityId");
+            }
+
+            this.id = activityId;
+        }
+
         /// <summary>
         /// Cloning constructor (all fields are value types - can treat our implementation of cloning as "deep" copy)
         /// </summary>
@@ -488,9 +507,13 @@ internal static ProgressRecord FromPSObjectForRemoting(PSObject progressAsPSObje
         /// <returns>This object as a PSObject property bag.</returns>
         internal PSObject ToPSObjectForRemoting()
         {
-            PSObject progressAsPSObject = RemotingEncoder.CreateEmptyPSObject();
+            // Activity used to be mandatory but that's no longer the case.
+            // We ensure the string has a value to maintain compatibility with older versions.
+            string activity = string.IsNullOrEmpty(Activity) ? " " : Activity;
 
-            progressAsPSObject.Properties.Add(new PSNoteProperty(RemoteDataNameStrings.ProgressRecord_Activity, this.Activity));
+            PSObject progressAsPSObject = RemotingEncoder.CreateEmptyPSObject();
+
+            progressAsPSObject.Properties.Add(new PSNoteProperty(RemoteDataNameStrings.ProgressRecord_Activity, activity));
             progressAsPSObject.Properties.Add(new PSNoteProperty(RemoteDataNameStrings.ProgressRecord_ActivityId, this.ActivityId));
             progressAsPSObject.Properties.Add(new PSNoteProperty(RemoteDataNameStrings.ProgressRecord_StatusDescription, this.StatusDescription));
 

diff --git a/test/powershell/Modules/Microsoft.PowerShell.Utility/Write-Progress.Tests.ps1 b/test/powershell/Modules/Microsoft.PowerShell.Utility/Write-Progress.Tests.ps1
@@ -1,10 +1,6 @@
 # Copyright (c) Microsoft Corporation.
 # Licensed under the MIT License.
 Describe "Write-Progress DRT Unit Tests" -Tags "CI" {
-    It "Should be able to throw exception when missing mandatory parameters" {
-        { Write-Progress $null } | Should -Throw -ErrorId 'ParameterArgumentValidationErrorNullNotAllowed,Microsoft.PowerShell.Commands.WriteProgressCommand'
-    }
-
     It "Should be able to throw exception when running Write-Progress with bad percentage" {
         { Write-Progress -Activity 'myactivity' -Status 'mystatus' -percent 101 } |
 	    Should -Throw -ErrorId 'ParameterArgumentValidationError,Microsoft.PowerShell.Commands.WriteProgressCommand'
@@ -33,4 +29,8 @@ Describe "Write-Progress DRT Unit Tests" -Tags "CI" {
         { Write-Progress -Activity $activity -Status ('b' * ([console]::WindowWidth + 1)) -Id 1 } | Should -Not -Throw
         Write-Progress -Activity $activity -Id 1 -Completed
     }
+
+    It 'Should be able to complete a progress record with no activity specified' {
+        { Write-Progress -Completed } | Should -Not -Throw
+    }
 }