refactor: improve lockfile detection robustness

justin808 · claude · justin808 · commit b91877f9c6ef · 2025-11-10T14:19:42.000-10:00
- Reduce File.read size from 1000 to 300 chars for efficiency - Add error handling for corrupted/unreadable lockfiles - Add tests for error scenarios to improve branch coverage - Default to Yarn Classic on read errors Addresses code review feedback. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
diff --git a/lib/package_json.rb b/lib/package_json.rb
@@ -116,18 +116,20 @@ def detect_manager_from_lockfile
 
   def detect_yarn_version_from_lockfile
     lockfile_path = "#{directory}/yarn.lock"
-    return nil unless File.exist?(lockfile_path)
 
     # Read the first few lines to determine the version
-    # Yarn Berry lockfiles start with "__metadata:" or have "# yarn lockfile v1" but use a different format
-    # Yarn Classic lockfiles start with "# THIS IS AN AUTOGENERATED FILE" and "# yarn lockfile v1"
-    content = File.read(lockfile_path, 1000) # Read first 1000 chars
+    # Yarn Berry lockfiles start with "__metadata:" within the first few lines
+    # Yarn Classic lockfiles use the older format without __metadata:
+    content = File.read(lockfile_path, 300) # Read first 300 chars - sufficient to detect __metadata:
 
     # Yarn Berry uses __metadata: at the start
     return :yarn_berry if content.include?("__metadata:")
 
     # Default to Yarn Classic for older format
     :yarn_classic
+  rescue StandardError
+    # On error (e.g., file read failure, corrupted lockfile), default to Yarn Classic
+    :yarn_classic
   end
 
   def determine_yarn_version(version)
diff --git a/spec/package_json_spec.rb b/spec/package_json_spec.rb
@@ -189,6 +189,17 @@
         end
       end
 
+      it "defaults to yarn classic if yarn.lock is unreadable" do
+        with_package_json_file({ "version" => "1.0.0" }) do
+          File.write("yarn.lock", "")
+          allow(File).to receive(:read).and_call_original
+          allow(File).to receive(:read).with("#{Dir.pwd}/yarn.lock", 300).and_raise(StandardError)
+          package_json = described_class.read(Dir.pwd, fallback_manager: :npm)
+
+          expect(package_json.manager).to be_a PackageJson::Managers::YarnClassicLike
+        end
+      end
+
       it "prioritizes bun.lockb over other lockfiles" do
         with_package_json_file({ "version" => "1.0.0" }) do
           File.write("bun.lockb", "")
@@ -436,6 +447,17 @@
         end
       end
 
+      it "defaults to yarn classic if yarn.lock is unreadable" do
+        with_package_json_file({ "version" => "1.0.0" }) do
+          File.write("yarn.lock", "")
+          allow(File).to receive(:read).and_call_original
+          allow(File).to receive(:read).with("#{Dir.pwd}/yarn.lock", 300).and_raise(StandardError)
+          package_json = described_class.new(fallback_manager: :npm)
+
+          expect(package_json.manager).to be_a PackageJson::Managers::YarnClassicLike
+        end
+      end
+
       it "does not add the packageManager property" do
         with_package_json_file({ "version" => "1.0.0" }) do
           described_class.new(fallback_manager: :yarn_classic)
