Fix git-lfs unnecessary hook installation

Fix an issue where git lfs install was running unnecessarily in repositories
without LFS files, causing hooks to be installed when they shouldn't be.

Changes:
- Update src/git-lfs/install.sh to properly check for empty git lfs ls-files output
- Add comprehensive test (test/git-lfs/noLfsFiles.sh) to verify hooks are not installed
  when no LFS files are present
- Update test scenarios to include the new test case

The fix changes the condition from checking command exit status to checking
if the output is empty, preventing unnecessary hook installation in non-LFS repos.

Author: yaegashi

src/git-lfs/install.sh

@@ -266,7 +266,7 @@ if [ "${AUTO_PULL}" != "true" ]; then
 fi
 
 # Check if repo is a git lfs repo.
-if ! git lfs ls-files > /dev/null 2>&1; then
+if [ -z "$(git lfs ls-files 2>/dev/null)" ]; then
     echo "(!) Skipping automatic 'git lfs pull' because no git lfs files were detected"
     exit 0
 fi

test/git-lfs/noLfsFiles.sh

@@ -0,0 +1,52 @@
+#!/bin/bash
+
+set -e
+
+# Test for git-lfs behavior with repos that have no LFS files
+# This tests the fix for the issue where git lfs install was running unnecessarily
+
+# Optional: Import test library
+source dev-container-features-test-lib
+
+# Test that git-lfs is installed
+check "git-lfs version" git-lfs --version
+
+# Test the generated script exists
+check "pull script exists" test -f /usr/local/share/pull-git-lfs-artifacts.sh
+
+# Create a mock git repo without LFS files to test the script
+mkdir -p /tmp/test-no-lfs-repo
+cd /tmp/test-no-lfs-repo
+git init
+git config user.email "[email protected]"
+git config user.name "Test User"
+echo "regular file content" > regular.txt
+git add regular.txt
+git commit -m "Initial commit without LFS"
+
+# Test that git lfs ls-files returns empty output (our fix checks this)
+check "git lfs ls-files returns empty output" test -z "$(git lfs ls-files 2>/dev/null)"
+
+# Verify no hooks exist before running the script
+HOOKS_BEFORE=$(find .git/hooks -type f ! -name '*.sample' | wc -l)
+check "no git hooks before script" test "$HOOKS_BEFORE" -eq 0
+
+# Run the actual pull-git-lfs-artifacts.sh script to test the real behavior
+echo "Running pull-git-lfs-artifacts.sh script..."
+/usr/local/share/pull-git-lfs-artifacts.sh
+
+# Verify that git lfs install was NOT executed by checking no hooks were installed
+HOOKS_AFTER=$(find .git/hooks -type f ! -name '*.sample' | wc -l)
+check "no git hooks installed after script" test "$HOOKS_AFTER" -eq 0
+
+# Double check: specifically look for the hooks that git lfs install would create
+check "no post-merge hook" test ! -f .git/hooks/post-merge
+check "no pre-push hook" test ! -f .git/hooks/pre-push
+check "no post-commit hook" test ! -f .git/hooks/post-commit
+check "no post-checkout hook" test ! -f .git/hooks/post-checkout
+
+# Clean up
+cd /tmp
+rm -rf /tmp/test-no-lfs-repo
+
+reportResults

test/git-lfs/scenarios.json

@@ -19,6 +19,13 @@
             }
         }
     },
+    "noLfsFiles": {
+        "image": "mcr.microsoft.com/devcontainers/base:ubuntu",
+        "remoteUser": "vscode",
+        "features": {
+            "git-lfs": {}
+        }
+    },
     "use_github": {
         "image": "mcr.microsoft.com/devcontainers/base:ubuntu",
         "remoteUser": "vscode",