Exclude redundant parameter aliases from completion results (#19382)

src/System.Management.Automation/engine/CommandCompletion/CompletionCompleters.cs

@@ -719,13 +719,21 @@ namespace System.Management.Automation
                 string tooltip = parameterType + matchedParameterName;
                 result.Add(new CompletionResult(completionText, matchedParameterName, CompletionResultType.ParameterName, tooltip));
             }
-
-            // Process alias when there is partial input
-            result.AddRange(from alias in param.Parameter.Aliases
-                            where pattern.IsMatch(alias)
-                            select
-                                new CompletionResult("-" + alias + colonSuffix, alias, CompletionResultType.ParameterName,
-                                                     parameterType + alias));
+            else
+            {
+                // Process alias when there is partial input
+                foreach (var alias in param.Parameter.Aliases)
+                {
+                    if (pattern.IsMatch(alias))
+                    {
+                        result.Add(new CompletionResult(
+                            $"-{alias}{colonSuffix}",
+                            alias,
+                            CompletionResultType.ParameterName,
+                            parameterType + alias));
+                    }
+                }
+            }
 
             return result;
         }
@@ -791,15 +799,20 @@ namespace System.Management.Automation
                                                            tooltip));
                     }
                 }
-
-                if (parameterName != string.Empty)
+                else if (parameterName != string.Empty)
                 {
                     // Process alias when there is partial input
-                    listInUse.AddRange(from alias in param.Parameter.Aliases
-                                       where pattern.IsMatch(alias)
-                                       select
-                                         new CompletionResult("-" + alias + colonSuffix, alias, CompletionResultType.ParameterName,
-                                                              type + alias));
+                    foreach (var alias in param.Parameter.Aliases)
+                    {
+                        if (pattern.IsMatch(alias))
+                        {
+                            listInUse.Add(new CompletionResult(
+                                $"-{alias}{colonSuffix}",
+                                alias,
+                                CompletionResultType.ParameterName,
+                                type + alias));
+                        }
+                    }
                 }
             }
 

test/powershell/Host/TabCompletion/BugFix.Tests.ps1

@@ -28,10 +28,9 @@ Describe "Tab completion bug fix" -Tags "CI" {
     It "Issue#1345 - 'Import-Module -n<tab>' should work" {
         $cmd = "Import-Module -n"
         $result = TabExpansion2 -inputScript $cmd -cursorColumn $cmd.Length
-        $result.CompletionMatches | Should -HaveCount 3
+        $result.CompletionMatches | Should -HaveCount 2
         $result.CompletionMatches[0].CompletionText | Should -BeExactly "-Name"
         $result.CompletionMatches[1].CompletionText | Should -BeExactly "-NoClobber"
-        $result.CompletionMatches[2].CompletionText | Should -BeExactly "-NoOverwrite"
     }
 
     It "Issue#11227 - [CompletionCompleters]::CompleteVariable and [CompletionCompleters]::CompleteType should work" {

test/powershell/Host/TabCompletion/TabCompletion.Tests.ps1

@@ -871,6 +871,18 @@ class InheritedClassTest : System.Attribute
         $res.CompletionMatches.CompletionText | Should -Contain 'TypeId'
     }
 
+    it 'Should not complete parameter aliases if the real parameter is in the completion results' {
+        $res = TabExpansion2 -inputScript 'Get-ChildItem -p'
+        $res.CompletionMatches.CompletionText | Should -Not -Contain '-proga'
+        $res.CompletionMatches.CompletionText | Should -Contain '-ProgressAction'
+    }
+
+    it 'Should not complete parameter aliases if the real parameter is in the completion results (Non ambiguous parameters)' {
+        $res = TabExpansion2 -inputScript 'Get-ChildItem -prog'
+        $res.CompletionMatches.CompletionText | Should -Not -Contain '-proga'
+        $res.CompletionMatches.CompletionText | Should -Contain '-ProgressAction'
+    }
+
     Context "Script name completion" {
         BeforeAll {
             Setup -f 'install-powershell.ps1' -Content ""
@@ -1646,15 +1658,15 @@ dir -Recurse `
         It "Test completion with exact match" {
             $inputStr = 'get-content -wa'
             $res = TabExpansion2 -inputScript $inputStr -cursorColumn $inputStr.Length
-            $res.CompletionMatches | Should -HaveCount 4
-            [string]::Join(',', ($res.CompletionMatches.completiontext | Sort-Object)) | Should -BeExactly "-wa,-Wait,-WarningAction,-WarningVariable"
+            $res.CompletionMatches | Should -HaveCount 3
+            [string]::Join(',', ($res.CompletionMatches.completiontext | Sort-Object)) | Should -BeExactly "-Wait,-WarningAction,-WarningVariable"
         }
 
         It "Test completion with splatted variable" {
             $inputStr = 'Get-Content @Splat -P'
             $res = TabExpansion2 -inputScript $inputStr -cursorColumn $inputStr.Length
-            $res.CompletionMatches | Should -HaveCount 6
-            [string]::Join(',', ($res.CompletionMatches.completiontext | Sort-Object)) | Should -BeExactly "-Path,-PipelineVariable,-proga,-ProgressAction,-PSPath,-pv"
+            $res.CompletionMatches | Should -HaveCount 4
+            [string]::Join(',', ($res.CompletionMatches.completiontext | Sort-Object)) | Should -BeExactly "-Path,-PipelineVariable,-ProgressAction,-PSPath"
         }
 
         It "Test completion for HttpVersion parameter name" {