Marius Storhaug (MariusStorhaug) · Nov 2, 2026 · Nov 2, 2026 · Nov 3, 2026
diff --git a/README.md b/README.md
@@ -28,6 +28,12 @@ The following labels will inform the action what kind of release to create:
 
 When a pull request is closed, the action will create a release based on the labels and clean up any previous prereleases that were created.
 
+Cleanup only deletes releases marked as prereleases whose version tags match the configured `VersionPrefix` and the exact sanitized
+branch name as the first prerelease identifier. Both matches are case-sensitive.
+Plain, incremental, and date-based branch prereleases are supported.
+Stable releases and unrelated branch prereleases are never selected. If removing non-alphanumeric characters leaves the branch name empty
+(for example, `_` or `-`), cleanup is skipped with a warning. Cleanup also runs when an unmerged pull request is closed.
+
 > [!NOTE]
 > The labels can be configured using the `MajorLabels`, `MinorLabels` and `PatchLabels` parameters/settings in the configuration file to trigger
 > on other labels.
@@ -116,3 +122,14 @@ permissions:
   contents: write # Required to create releases
   pull-requests: write # Required to create comments on the PRs
 ```
+
+## Local cleanup tests
+
+With PowerShell 7, Pester 6, and PSSemVer installed, run:
+
+```powershell
+Invoke-Pester -Path .\tests\ReleaseCleanup.Tests.ps1 -Output Detailed
+```
+
+The tests run the action script with isolated pull request events and release fixtures.
+GitHub and git commands are mocked so no real releases or tags are created or deleted.
diff --git a/src/main.ps1 b/src/main.ps1
@@ -365,7 +365,18 @@ if ($createPrerelease -or $createRelease -or $whatIf) {
 }
 
 LogGroup 'List prereleases using the same name' {
-    $prereleasesToCleanup = $releases | Where-Object { $_.tagName -like "*$prereleaseName*" }
+    $prereleasesToCleanup = @()
+    if ([string]::IsNullOrEmpty($prereleaseName)) {
+        Write-Warning "Skipping prerelease cleanup: branch [$prHeadRef] has no alphanumeric prerelease name."
+    } else {
+        # Match the first SemVer prerelease identifier, not a substring of the tag.
+        $escapedVersionPrefix = [regex]::Escape($versionPrefix)
+        $escapedPrereleaseName = [regex]::Escape($prereleaseName)
+        $prereleaseTagPattern = "^${escapedVersionPrefix}[0-9]+\.[0-9]+\.[0-9]+-${escapedPrereleaseName}(?:\.|$)"
+        $prereleasesToCleanup = $releases | Where-Object {
+            $_.isPrerelease -eq $true -and $_.tagName -cmatch $prereleaseTagPattern
+        }
+    }
     $prereleasesToCleanup | Select-Object -Property name, publishedAt, isPrerelease, isLatest | Format-Table | Out-String
 }
 

diff --git a/tests/ReleaseCleanup.Tests.ps1 b/tests/ReleaseCleanup.Tests.ps1
@@ -0,0 +1,333 @@
+#Requires -Version 7.0
+#Requires -Modules @{ ModuleName = 'Pester'; ModuleVersion = '6.0.0'; MaximumVersion = '6.*' }
+#Requires -Modules PSSemVer
+
+[Diagnostics.CodeAnalysis.SuppressMessageAttribute(
+    'PSUseDeclaredVarsMoreThanAssignments', '', Justification = 'Variables are used by Pester test blocks.'
+)]
+[Diagnostics.CodeAnalysis.SuppressMessageAttribute(
+    'PSAvoidGlobalVars', '', Justification = 'Native command mocks share fixture state across script scopes and restore it after tests.'
+)]
+[CmdletBinding()]
+param()
+
+$ErrorActionPreference = 'Stop'
+
+BeforeAll {
+    Import-Module -Name PSSemVer
+    $script:mainPath = Join-Path -Path $PSScriptRoot -ChildPath '..\src\main.ps1'
+    $script:previousExitCode = $global:LASTEXITCODE
+    $script:previousTestState = $global:ReleaseCleanupTestState
+    $global:ReleaseCleanupTestState = @{}
+    $script:previousEnvironment = @{}
+    $script:inputDefaults = @{
+        GITHUB_EVENT_PATH                                    = Join-Path -Path $TestDrive -ChildPath 'event.json'
+        PSMODULE_AUTO_RELEASE_INPUT_ConfigurationFile        = Join-Path -Path $TestDrive -ChildPath 'missing.yml'
+        PSMODULE_AUTO_RELEASE_INPUT_AutoCleanup              = 'true'
+        PSMODULE_AUTO_RELEASE_INPUT_AutoPatching             = 'true'
+        PSMODULE_AUTO_RELEASE_INPUT_CreateMajorTag           = 'true'
+        PSMODULE_AUTO_RELEASE_INPUT_CreateMinorTag           = 'true'
+        PSMODULE_AUTO_RELEASE_INPUT_DatePrereleaseFormat     = ''
+        PSMODULE_AUTO_RELEASE_INPUT_IgnoreLabels             = 'NoRelease'
+        PSMODULE_AUTO_RELEASE_INPUT_IncrementalPrerelease    = 'true'
+        PSMODULE_AUTO_RELEASE_INPUT_MajorLabels              = 'major, breaking'
+        PSMODULE_AUTO_RELEASE_INPUT_MinorLabels              = 'minor, feature'
+        PSMODULE_AUTO_RELEASE_INPUT_PatchLabels              = 'patch, fix'
+        PSMODULE_AUTO_RELEASE_INPUT_UsePRBodyAsReleaseNotes  = 'true'
+        PSMODULE_AUTO_RELEASE_INPUT_UsePRTitleAsReleaseName  = 'false'
+        PSMODULE_AUTO_RELEASE_INPUT_UsePRTitleAsNotesHeading = 'true'
+        PSMODULE_AUTO_RELEASE_INPUT_VersionPrefix            = 'v'
+        PSMODULE_AUTO_RELEASE_INPUT_WhatIf                   = 'false'
+    }
+    foreach ($name in $script:inputDefaults.Keys) {
+        $script:previousEnvironment[$name] = [Environment]::GetEnvironmentVariable($name)
+    }
+
+    function Invoke-TestLogGroup {
+        <#
+            .SYNOPSIS
+            Run an action log group in its shared script context.
+
+            .DESCRIPTION
+            Preserve the action's shared variables without depending on the GitHub logging runtime.
+            This adapter does not validate the external logging integration.
+
+            .EXAMPLE
+            Invoke-TestLogGroup -Name 'Example' -ScriptBlock { $value = 1 }
+            Make the group's value available to the calling script.
+        #>
+        [Alias('LogGroup')]
+        [CmdletBinding()]
+        param(
+            # The log group name.
+            [Parameter(Mandatory, Position = 0)]
+            [string] $Name,
+
+            # The action code to execute.
+            [Parameter(Mandatory, Position = 1)]
+            [scriptblock] $ScriptBlock
+        )
+
+        Write-Verbose -Message "Running test log group [$Name]."
+        $initialVariables = @(Get-Variable -Scope Local | Select-Object -ExpandProperty Name)
+        . $ScriptBlock
+        foreach ($variable in Get-Variable -Scope Local) {
+            if ($variable.Name -notin $initialVariables -and $variable.Name -notin @('initialVariables', 'variable')) {
+                Set-Variable -Name $variable.Name -Value $variable.Value -Scope 1
+            }
+        }
+    }
+
+    function Write-GitHubNotice {
+        <#
+            .SYNOPSIS
+            Accept a simulated action notice.
+
+            .DESCRIPTION
+            Avoid depending on the GitHub logging runtime in local tests.
+
+            .EXAMPLE
+            Write-GitHubNotice -Title 'Release created' -Message 'v1.2.4'
+            Accept the action's notice without writing to GitHub.
+        #>
+        [CmdletBinding()]
+        param(
+            # The notice title.
+            [Parameter()]
+            [string] $Title,
+
+            # The notice message.
+            [Parameter()]
+            [string] $Message
+        )
+
+        Write-Verbose -Message "$Title`: $Message"
+    }
+}
+
+Describe 'Branch prerelease cleanup' {
+    BeforeEach {
+        foreach ($name in $script:inputDefaults.Keys) {
+            [Environment]::SetEnvironmentVariable($name, $script:inputDefaults[$name])
+        }
+        $script:event = @{
+            action       = 'closed'
+            pull_request = @{
+                merged = $false
+                state  = 'closed'
+                head   = @{ ref = 'feature/test' }
+                base   = @{ ref = 'main' }
+                labels = @()
+                number = 42
+                title  = 'Test release'
+                body   = 'Test release notes'
+            }
+        }
+        $global:ReleaseCleanupTestState.Releases = @(
+            [pscustomobject]@{ tagName = 'v1.2.3'; isPrerelease = $false; isLatest = $true }
+            [pscustomobject]@{ tagName = 'v0.1.0'; isPrerelease = $false; isLatest = $false }
+            [pscustomobject]@{ tagName = 'v1.0.0-featuretest'; isPrerelease = $false; isLatest = $false }
+            [pscustomobject]@{ tagName = 'v1.2.4-featuretest'; isPrerelease = $true; isLatest = $false }
+            [pscustomobject]@{ tagName = 'v1.2.4-featuretest.1'; isPrerelease = $true; isLatest = $false }
+            [pscustomobject]@{ tagName = 'v1.2.4-featuretest.20261102.2'; isPrerelease = $true; isLatest = $false }
+            [pscustomobject]@{ tagName = 'v1.2.4-featuretestextra.1'; isPrerelease = $true; isLatest = $false }
+            [pscustomobject]@{ tagName = 'v1.2.4-otherfeaturetest.1'; isPrerelease = $true; isLatest = $false }
+            [pscustomobject]@{ tagName = 'v1.2.4-other.1+featuretest'; isPrerelease = $true; isLatest = $false }
+            [pscustomobject]@{ tagName = 'v1.2.4-other.1'; isPrerelease = $true; isLatest = $false }
+            [pscustomobject]@{ tagName = 'notversion-featuretest.1'; isPrerelease = $true; isLatest = $false }
+            [pscustomobject]@{ tagName = 'v1.2.4.5-featuretest.1'; isPrerelease = $true; isLatest = $false }
+            [pscustomobject]@{ tagName = 'v1.2.4-featuretest.3'; isLatest = $false }
+            [pscustomobject]@{ tagName = 'v1.2.4-featuretest.4'; isPrerelease = $null; isLatest = $false }
+        )
+        $script:deletedTags = [System.Collections.Generic.List[string]]::new()
+        $global:ReleaseCleanupTestState.DeletedTags = $script:deletedTags
+        $global:LASTEXITCODE = 0
+
+        # Destructive GitHub and git boundaries are simulated; no real releases or tags are changed.
+        Mock -CommandName Install-PSResource {}
+        Mock -CommandName Import-Module {}
+        Mock -CommandName git {}
+        Mock -CommandName gh {
+            if ($args[0] -eq 'repo' -and $args[1] -eq 'view') {
+                return '{"defaultBranchRef":{"name":"main"}}'
+            }
+            if ($args[0] -eq 'release' -and $args[1] -eq 'list') {
+                return ConvertTo-Json -InputObject $global:ReleaseCleanupTestState.Releases
+            }
+            if ($args[0] -eq 'release' -and $args[1] -eq 'delete') {
+                $global:ReleaseCleanupTestState.DeletedTags.Add($args[2])
+                return
+            }
+            if ($args[0] -eq 'release' -and $args[1] -eq 'create') {
+                return 'https://example.invalid/releases/test'
+            }
+            if ($args[0] -eq 'pr' -and $args[1] -eq 'comment') {
+                return
+            }
+            throw "Unexpected gh command: $($args -join ' ')"
+        }
+    }
+
+    AfterEach {
+        foreach ($name in $script:previousEnvironment.Keys) {
+            [Environment]::SetEnvironmentVariable($name, $script:previousEnvironment[$name])
+        }
+        $global:LASTEXITCODE = $script:previousExitCode
+    }
+
+    It 'Does not delete any release for the empty identifier from branch "<BranchName>" (merged: <Merged>)' -ForEach @(
+        @{ BranchName = ''; Merged = $false }
+        @{ BranchName = '_'; Merged = $false }
+        @{ BranchName = '-'; Merged = $false }
+        @{ BranchName = '---___'; Merged = $false }
+        @{ BranchName = ''; Merged = $true }
+        @{ BranchName = '_'; Merged = $true }
+        @{ BranchName = '-'; Merged = $true }
+        @{ BranchName = '---___'; Merged = $true }
+    ) {
+        $script:event.pull_request.head.ref = $BranchName
+        $script:event.pull_request.merged = $Merged
+        $script:event | ConvertTo-Json -Depth 5 | Set-Content -Path $env:GITHUB_EVENT_PATH
+
+        & $script:mainPath | Out-Null
+
+        $script:deletedTags.Count | Should -Be 0
+    }
+
+    It 'Deletes only exact branch prereleases for short or common branch "<BranchName>"' -ForEach @(
+        @{ BranchName = 'v1'; ExpectedTag = 'v1.2.4-v1.1' }
+        @{ BranchName = '1'; ExpectedTag = 'v1.2.4-1.1' }
+        @{ BranchName = '0'; ExpectedTag = 'v1.2.4-0.1' }
+    ) {
+        $script:event.pull_request.head.ref = $BranchName
+        $global:ReleaseCleanupTestState.Releases += @(
+            [pscustomobject]@{ tagName = $ExpectedTag; isPrerelease = $true; isLatest = $false }
+            [pscustomobject]@{ tagName = "v1.2.4-${BranchName}extra.1"; isPrerelease = $true; isLatest = $false }
+            [pscustomobject]@{ tagName = "v1.2.4-other${BranchName}.1"; isPrerelease = $true; isLatest = $false }
+            [pscustomobject]@{ tagName = "v1.0.0-${BranchName}"; isPrerelease = $false; isLatest = $false }
+        )
+        $script:event | ConvertTo-Json -Depth 5 | Set-Content -Path $env:GITHUB_EVENT_PATH
+
+        & $script:mainPath | Out-Null
+
+        $script:deletedTags.Count | Should -Be 1
+        $script:deletedTags[0] | Should -BeExactly $ExpectedTag
+    }
+
+    It 'Cleans up plain, incremental, and date-based branch prereleases (merged: <Merged>)' -ForEach @(
+        @{ Merged = $false }
+        @{ Merged = $true }
+    ) {
+        $script:event.pull_request.merged = $Merged
+        $script:event | ConvertTo-Json -Depth 5 | Set-Content -Path $env:GITHUB_EVENT_PATH
+
+        & $script:mainPath | Out-Null
+
+        $script:deletedTags.Count | Should -Be 3
+        $script:deletedTags[0] | Should -BeExactly 'v1.2.4-featuretest'
+        $script:deletedTags[1] | Should -BeExactly 'v1.2.4-featuretest.1'
+        $script:deletedTags[2] | Should -BeExactly 'v1.2.4-featuretest.20261102.2'
+        if ($Merged) {
+            Should -Invoke -CommandName gh -Times 1 -Exactly -ParameterFilter {
+                $args[0] -eq 'release' -and $args[1] -eq 'create' -and $args[2] -eq 'v1.2.4'
+            }
+        }
+    }
+
+    It 'Matches branch identifiers and version prefixes case-sensitively for "<BranchName>"' -ForEach @(
+        @{ BranchName = 'feature/test'; ExpectedTag = 'v1.2.4-featuretest.1' }
+        @{ BranchName = 'Feature/Test'; ExpectedTag = 'v1.2.4-FeatureTest.1' }
+    ) {
+        $script:event.pull_request.head.ref = $BranchName
+        $global:ReleaseCleanupTestState.Releases = @(
+            [pscustomobject]@{ tagName = 'v1.2.3'; isPrerelease = $false; isLatest = $true }
+            [pscustomobject]@{ tagName = 'v1.2.4-featuretest.1'; isPrerelease = $true; isLatest = $false }
+            [pscustomobject]@{ tagName = 'v1.2.4-FeatureTest.1'; isPrerelease = $true; isLatest = $false }
+            [pscustomobject]@{ tagName = 'V1.2.4-featuretest.1'; isPrerelease = $true; isLatest = $false }
+            [pscustomobject]@{ tagName = 'V1.2.4-FeatureTest.1'; isPrerelease = $true; isLatest = $false }
+        )
+        $script:event | ConvertTo-Json -Depth 5 | Set-Content -Path $env:GITHUB_EVENT_PATH
+
+        & $script:mainPath | Out-Null
+
+        $script:deletedTags.Count | Should -Be 1
+        $script:deletedTags[0] | Should -BeExactly $ExpectedTag
+    }
+
+    It 'Honors AutoCleanup being disabled' {
+        $env:PSMODULE_AUTO_RELEASE_INPUT_AutoCleanup = 'false'
+        $script:event | ConvertTo-Json -Depth 5 | Set-Content -Path $env:GITHUB_EVENT_PATH
+
+        & $script:mainPath | Out-Null
+
+        $script:deletedTags.Count | Should -Be 0
+    }
+
+    It 'Does not clean up while the pull request is open' {
+        $script:event.action = 'synchronize'
+        $script:event.pull_request.state = 'open'
+        $script:event | ConvertTo-Json -Depth 5 | Set-Content -Path $env:GITHUB_EVENT_PATH
+
+        & $script:mainPath | Out-Null
+
+        $script:deletedTags.Count | Should -Be 0
+    }
+
+    It 'Honors a custom literal version prefix' {
+        $env:PSMODULE_AUTO_RELEASE_INPUT_VersionPrefix = 'release.v'
+        $global:ReleaseCleanupTestState.Releases += @(
+            [pscustomobject]@{ tagName = 'release.v1.2.4-featuretest.1'; isPrerelease = $true; isLatest = $false }
+            [pscustomobject]@{ tagName = 'releaseXv1.2.4-featuretest.1'; isPrerelease = $true; isLatest = $false }
+        )
+        $script:event | ConvertTo-Json -Depth 5 | Set-Content -Path $env:GITHUB_EVENT_PATH
+
+        & $script:mainPath | Out-Null
+
+        $script:deletedTags.Count | Should -Be 1
+        $script:deletedTags[0] | Should -BeExactly 'release.v1.2.4-featuretest.1'
+    }
+
+    It 'Supports tags without a version prefix' {
+        $env:PSMODULE_AUTO_RELEASE_INPUT_VersionPrefix = ''
+        $global:ReleaseCleanupTestState.Releases += @(
+            [pscustomobject]@{ tagName = '1.2.4-featuretest.1'; isPrerelease = $true; isLatest = $false }
+            [pscustomobject]@{ tagName = '1.2.3'; isPrerelease = $false; isLatest = $false }
+        )
+        $script:event | ConvertTo-Json -Depth 5 | Set-Content -Path $env:GITHUB_EVENT_PATH
+
+        & $script:mainPath | Out-Null
+
+        $script:deletedTags.Count | Should -Be 1
+        $script:deletedTags[0] | Should -BeExactly '1.2.4-featuretest.1'
+    }
+
+    It 'Previews only intended deletions in WhatIf mode for branch "<BranchName>"' -ForEach @(
+        @{ BranchName = '_'; ExpectedTags = @() }
+        @{ BranchName = '1'; ExpectedTags = @('v1.2.4-1.1') }
+        @{
+            BranchName   = 'feature/test'
+            ExpectedTags = @('v1.2.4-featuretest', 'v1.2.4-featuretest.1', 'v1.2.4-featuretest.20261102.2')
+        }
+    ) {
+        $env:PSMODULE_AUTO_RELEASE_INPUT_WhatIf = 'true'
+        $script:event.pull_request.head.ref = $BranchName
+        $global:ReleaseCleanupTestState.Releases += [pscustomobject]@{
+            tagName = 'v1.2.4-1.1'; isPrerelease = $true; isLatest = $false
+        }
+        $script:event | ConvertTo-Json -Depth 5 | Set-Content -Path $env:GITHUB_EVENT_PATH
+
+        $output = & $script:mainPath
+
+        $previews = @($output | Where-Object { $_ -like 'WhatIf: gh release delete *' })
+        $previews.Count | Should -Be $ExpectedTags.Count
+        for ($index = 0; $index -lt $ExpectedTags.Count; $index++) {
+            $previews[$index] | Should -BeExactly "WhatIf: gh release delete $($ExpectedTags[$index]) --cleanup-tag --yes"
+        }
+        $script:deletedTags.Count | Should -Be 0
+        Should -Invoke -CommandName git -Times 0 -Exactly
+    }
+}
+
+AfterAll {
+    $global:ReleaseCleanupTestState = $script:previousTestState
+}