Add tab completion for $PSBoundParameters.Keys switch cases and access patterns by yotsuda · Pull Request #26483 · PowerShell/PowerShell

yotsuda · 2025-11-19T03:36:25Z

PR Summary

Add tab completion for parameter names when working with $PSBoundParameters in various access patterns.

PR Context

When writing functions that use $PSBoundParameters to check which parameters were bound, it's easy to make typos in parameter names. This PR adds tab completion support to help prevent such errors.

PR Checklist

PR has a meaningful title
Summarized changes
Make sure all .h, .cpp, .cs, .ps1 and .psm1 files have the correct copyright header
This PR is ready to merge and is not Work in Progress
Added a change log entry
Appropriate test coverage added

Description

This PR adds tab completion for parameter names in the following $PSBoundParameters access patterns:

Supported Patterns

Switch statement on Keys

switch ($PSBoundParameters.Keys) {
    Para<Tab>  # Completes to Param1, Param2, etc.
}

ContainsKey method

if ($PSBoundParameters.ContainsKey('<Tab>')) { }  # Completes to 'Param1', 'Param2', etc.

Indexer access

$value = $PSBoundParameters['<Tab>']  # Completes to 'Param1', 'Param2', etc.

Remove method

$PSBoundParameters.Remove('<Tab>')  # Completes to 'Param1', 'Param2', etc.

Implementation Details

Added CompleteAgainstSwitchCaseCondition method for switch case completion
Added CompleteAgainstPSBoundParametersAccess method for ContainsKey, indexer, and Remove patterns
Quote style is preserved (single or double quotes) in the completion text
Switch case completions use bare words (no quotes) as is standard for switch cases

Files Changed

src/System.Management.Automation/engine/CommandCompletion/CompletionAnalysis.cs - Added completion logic
test/powershell/Host/TabCompletion/TabCompletion.Tests.ps1 - Added 8 test cases

Testing

Manual Testing

function Test-Func {
    param(
        [string]$Param1,
        [string]$Param2,
        [int]$Count
    )
    
    # Test 1: Switch case - type 'P' then Tab
    switch ($PSBoundParameters.Keys) {
        P<Tab>  # Should complete to Param1, Param2
    }
    
    # Test 2: ContainsKey - type 'P' then Tab
    if ($PSBoundParameters.ContainsKey('P<Tab>')) { }  # Should complete to 'Param1', 'Param2'
    
    # Test 3: Indexer - type 'P' then Tab
    $value = $PSBoundParameters['P<Tab>']  # Should complete to 'Param1', 'Param2'
    
    # Test 4: Remove - type 'C' then Tab
    $PSBoundParameters.Remove('C<Tab>')  # Should complete to 'Count'
}

Automated Tests

8 new test cases added covering:

Switch case completion
ContainsKey method completion
Indexer access completion
Remove method completion
Double quote preservation
Non-PSBoundParameters variables (negative test)

When working with $PSBoundParameters, tab completion now suggests parameter names from the enclosing function or scriptblock's param block in the following scenarios: - switch ($PSBoundParameters.Keys) { <Tab> } - $PSBoundParameters.ContainsKey('<Tab>') - $PSBoundParameters['<Tab>'] - $PSBoundParameters.Remove('<Tab>') This helps prevent typos when writing code that checks or accesses bound parameter names. Fixes PowerShell#25349

iSazonov · 2025-11-19T05:58:54Z

@MartinGC94 Please review.

Copilot

Pull Request Overview

This PR adds tab completion for $PSBoundParameters parameter names to help prevent typos when accessing bound parameters. The feature supports switch cases on .Keys, as well as ContainsKey(), indexer access, and Remove() method calls.

Key Changes:

Adds two new completion methods that detect $PSBoundParameters usage patterns and provide parameter name completions
Integrates these methods into the existing completion pipeline at multiple entry points
Preserves quote style (single/double quotes) for quoted string contexts
Supports both complete and incomplete (error) switch statement ASTs

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
CompletionAnalysis.cs	Adds `CompleteAgainstSwitchCaseCondition` and `CompleteAgainstPSBoundParametersAccess` methods with AST analysis logic, integrated into string and identifier completion paths
TabCompletion.Tests.ps1	Adds 8 comprehensive test cases covering switch cases, ContainsKey, indexer, Remove methods, quote preservation, and negative test cases

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…letionAnalysis.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

MartinGC94

The overall logic seems fine but replace the "as" and null checks with pattern matching. Also unless something has changed, LINQ should generally be avoided.

…letionAnalysis.cs Co-authored-by: MartinGC94 <42123497+MartinGC94@users.noreply.github.com>

Copilot

Pull Request Overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

src/System.Management.Automation/engine/CommandCompletion/CompletionAnalysis.cs:395

This assignment to result is useless, since its value is never read.

            var result = new List<CompletionResult>();

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…letionAnalysis.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Copilot

Pull Request Overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

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- Remove useless initialization of result variable in CompleteAgainstPSBoundParametersAccess - Extract duplicate ParamBlock finding logic into FindNearestParamBlock helper method This refactoring improves code maintainability by reducing duplication between CompleteAgainstSwitchCaseCondition and CompleteAgainstPSBoundParametersAccess methods.

- Create CreateParameterCompletionResults helper method to reduce code duplication - Consolidate completion result generation logic between CompleteAgainstSwitchCaseCondition and CompleteAgainstPSBoundParametersAccess - Add optional quoteChar parameter to support both quoted and unquoted completion This addresses the second Copilot code review feedback and improves code maintainability.

Copilot

Pull Request Overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

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Addresses review feedback to test all code paths for non-PSBoundParameters variables. The original single negative test is now split into four separate tests covering indexer, ContainsKey, Remove, and double-quoted string access patterns.

iSazonov · 2025-11-25T04:43:24Z

+            var commandExpressionAst = conditionPipeline.PipelineElements[0] as CommandExpressionAst;
+            if (commandExpressionAst == null)
+            {
+                return null;


The same. I see below other such samples.

Thank you for the review feedback.
I've applied the commit suggestion and made additional changes to use modern C# patterns consistently:

Used is/is not pattern matching instead of as with null checks

Used is null/is not null instead of == null/!= null

Commit: 4439fbb

…letionAnalysis.cs Co-authored-by: Ilya <darpa@yandex.ru>

…s patterns (PowerShell#26483)

hamid01706169196 · 2026-05-04T20:35:10Z

25.79

yotsuda added 2 commits November 19, 2025 12:17

Fix trailing whitespace and test Context block structure

da9408d

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iSazonov added the CL-General Indicates that a PR should be marked as a general cmdlet change in the Change Log label Nov 19, 2025

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yotsuda and others added 4 commits November 19, 2025 16:27

Update src/System.Management.Automation/engine/CommandCompletion/Comp…

f87ff1a

…letionAnalysis.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Update src/System.Management.Automation/engine/CommandCompletion/Comp…

be01248

…letionAnalysis.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Update src/System.Management.Automation/engine/CommandCompletion/Comp…

8412e17

…letionAnalysis.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Refactor foreach loop to LINQ Any() for clause condition check

867fc9e

yotsuda marked this pull request as ready for review November 19, 2025 09:52

MartinGC94 suggested changes Nov 20, 2025

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microsoft-github-policy-service Bot added the Waiting on Author The PR was reviewed and requires changes or comments from the author before being accept label Nov 20, 2025

yotsuda and others added 2 commits November 20, 2025 09:28

Update src/System.Management.Automation/engine/CommandCompletion/Comp…

c107e44

…letionAnalysis.cs Co-authored-by: MartinGC94 <42123497+MartinGC94@users.noreply.github.com>

Update src/System.Management.Automation/engine/CommandCompletion/Comp…

f6a5119

…letionAnalysis.cs Co-authored-by: MartinGC94 <42123497+MartinGC94@users.noreply.github.com>

microsoft-github-policy-service Bot removed the Waiting on Author The PR was reviewed and requires changes or comments from the author before being accept label Nov 20, 2025

yotsuda and others added 4 commits November 20, 2025 09:28

Update src/System.Management.Automation/engine/CommandCompletion/Comp…

a17c6cf

…letionAnalysis.cs Co-authored-by: MartinGC94 <42123497+MartinGC94@users.noreply.github.com>

Update src/System.Management.Automation/engine/CommandCompletion/Comp…

12cbe5c

…letionAnalysis.cs Co-authored-by: MartinGC94 <42123497+MartinGC94@users.noreply.github.com>

Update src/System.Management.Automation/engine/CommandCompletion/Comp…

c673ff4

…letionAnalysis.cs Co-authored-by: MartinGC94 <42123497+MartinGC94@users.noreply.github.com>

Update src/System.Management.Automation/engine/CommandCompletion/Comp…

ed1d034

…letionAnalysis.cs Co-authored-by: MartinGC94 <42123497+MartinGC94@users.noreply.github.com>

iSazonov requested a review from Copilot November 20, 2025 12:01

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yotsuda and others added 3 commits November 20, 2025 21:35

Update src/System.Management.Automation/engine/CommandCompletion/Comp…

7303784

…letionAnalysis.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Update src/System.Management.Automation/engine/CommandCompletion/Comp…

c66e94f

…letionAnalysis.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Update src/System.Management.Automation/engine/CommandCompletion/Comp…

3ad98c5

…letionAnalysis.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

iSazonov requested a review from Copilot November 20, 2025 12:37

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Comment thread src/System.Management.Automation/engine/CommandCompletion/CompletionAnalysis.cs Outdated

Comment thread src/System.Management.Automation/engine/CommandCompletion/CompletionAnalysis.cs Outdated

yotsuda added 2 commits November 21, 2025 15:00

iSazonov requested a review from Copilot November 21, 2025 09:51

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iSazonov reviewed Nov 24, 2025

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

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yotsuda and others added 2 commits November 25, 2025 23:43

Update src/System.Management.Automation/engine/CommandCompletion/Comp…

970a183

…letionAnalysis.cs Co-authored-by: Ilya <darpa@yandex.ru>

Use modern C# pattern matching and 'is null' syntax

4439fbb

iSazonov approved these changes Nov 26, 2025

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iSazonov self-assigned this Nov 26, 2025

iSazonov merged commit 01e3643 into PowerShell:master Nov 26, 2025
36 checks passed

yotsuda deleted the feature/switch-psboundparameters-completion branch November 26, 2025 07:04

SIRMARGIN pushed a commit to SIRMARGIN/PowerShell that referenced this pull request Dec 12, 2025

Add tab completion for $PSBoundParameters.Keys switch cases and acces…

335310f

…s patterns (PowerShell#26483)

kilasuit pushed a commit to kilasuit/PowerShell that referenced this pull request Jan 2, 2026

Add tab completion for $PSBoundParameters.Keys switch cases and acces…

ac5dc6b

…s patterns (PowerShell#26483)

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yotsuda commented Nov 19, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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PR Summary

PR Context

PR Checklist

Description

Supported Patterns

Implementation Details

Files Changed

Testing

Manual Testing

Automated Tests

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iSazonov commented Nov 19, 2025

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yotsuda commented Nov 19, 2025 •

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