From 8bfb4aead8c7da227c7a7dde69aa9c20b3792521 Mon Sep 17 00:00:00 2001
From: Gilbert Sanchez <me@gilbertsanchez.com>
Date: Fri, 12 Jun 2026 21:10:34 -0700
Subject: [PATCH] fix: warn when Git target exists but is not a valid git
 repository (#86)

Previously, if a directory already existed at the clone target but was
not a git repository, `git rev-parse` returned nothing and the handler
silently fell into the "we don't support moving versions" branch with
null branch/commit values, producing a confusing verbose message and a
no-op install.

Now emits `Write-Warning` in that case so the user knows why the
dependency was skipped.

Also confirmed that the nesting bug from #86 (Repo/Repo on repeated runs)
does not reproduce on current code; adds two Pester tests to lock in
idempotency and the non-git-directory warning path.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 CHANGELOG.md                     | 13 ++++++++++++
 PSDepend/PSDependScripts/Git.ps1 |  6 +++++-
 Tests/Git.Type.Tests.ps1         | 35 ++++++++++++++++++++++++++++++++
 3 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2ddaf36..18f7557 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,19 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- `Git` handler no longer silently ignores a pre-existing directory at
+  the clone target that is not a valid git repository; it now emits a
+  `Write-Warning` so the user knows why the install was skipped (#86).
+
+### Tests
+
+- Added idempotency test: a second install run against an already-cloned
+  repo does not trigger a second `git clone` (#86).
+- Added non-git-directory test: confirms a warning is emitted and no
+  clone is attempted when the target path exists but is not a git repo (#86).
+
 ## [0.4.1] - 2026-06-12
 
 ### Fixed
diff --git a/PSDepend/PSDependScripts/Git.ps1 b/PSDepend/PSDependScripts/Git.ps1
index 64c4e7a..ad9b452 100644
--- a/PSDepend/PSDependScripts/Git.ps1
+++ b/PSDepend/PSDependScripts/Git.ps1
@@ -132,7 +132,11 @@ if ($GottaTest) {
     $Branch = Invoke-ExternalCommand git -Arguments (Write-Output rev-parse --abbrev-ref HEAD) -Passthru
     $Commit = Invoke-ExternalCommand git -Arguments (Write-Output rev-parse HEAD) -Passthru
     Pop-Location
-    if ($Version -eq $Branch -or $Version -eq $Commit) {
+    if (-not $Branch) {
+        Write-Warning "[$RepoPath] exists but does not appear to be a valid git repository. Skipping [$DependencyName]."
+        $GottaInstall = $False
+    }
+    elseif ($Version -eq $Branch -or $Version -eq $Commit) {
         Write-Verbose "[$RepoPath] exists and is already at version [$Version]"
         if ($PSDependAction -contains 'Test' -and $PSDependAction.count -eq 1) {
             return $true
diff --git a/Tests/Git.Type.Tests.ps1 b/Tests/Git.Type.Tests.ps1
index 848b94b..2175af4 100644
--- a/Tests/Git.Type.Tests.ps1
+++ b/Tests/Git.Type.Tests.ps1
@@ -74,4 +74,39 @@ Describe 'Git script' {
         $result | Should -Be $false
         Should -Invoke -CommandName Invoke-ExternalCommand -ModuleName PSDepend -Times 0
     }
+
+    It 'Does not clone again when repo already exists at the correct version (idempotency)' {
+        $targetDir = (New-Item 'TestDrive:/git-idempotent' -ItemType Directory -Force).FullName
+        # Pre-create the repo directory as if a prior run cloned it
+        $null = New-Item (Join-Path $targetDir 'repo') -ItemType Directory -Force
+        $dep = New-PSDependFixture -DependencyName 'https://example.com/user/repo.git' -DependencyType 'Git' -Version 'main' -Target $targetDir
+
+        InModuleScope PSDepend -Parameters @{ Dep = $dep; ScriptPath = $script:ScriptPath } {
+            # rev-parse returns the branch name matching Version
+            Mock Invoke-ExternalCommand {
+                if ($Arguments -contains '--abbrev-ref') { return 'main' }
+                if ($Arguments -notcontains 'clone' -and $Arguments -notcontains '--abbrev-ref') { return 'abc1234' }
+            }
+            & $ScriptPath -Dependency $Dep
+        }
+        Should -Invoke -CommandName Invoke-ExternalCommand -ModuleName PSDepend -Times 0 -ParameterFilter {
+            $Arguments -contains 'clone'
+        }
+    }
+
+    It 'Emits a warning and skips install when the repo path exists but is not a git repository' {
+        $targetDir = (New-Item 'TestDrive:/git-nongit' -ItemType Directory -Force).FullName
+        # Pre-create the directory but leave it empty (not a git repo)
+        $null = New-Item (Join-Path $targetDir 'repo') -ItemType Directory -Force
+        $dep = New-PSDependFixture -DependencyName 'https://example.com/user/repo.git' -DependencyType 'Git' -Version 'main' -Target $targetDir
+
+        InModuleScope PSDepend -Parameters @{ Dep = $dep; ScriptPath = $script:ScriptPath } {
+            # rev-parse returns nothing (non-git directory)
+            Mock Invoke-ExternalCommand { }
+            { & $ScriptPath -Dependency $Dep } | Should -Not -Throw
+        }
+        Should -Invoke -CommandName Invoke-ExternalCommand -ModuleName PSDepend -Times 0 -ParameterFilter {
+            $Arguments -contains 'clone'
+        }
+    }
 }