Add test for hang on loading library with symlink loop

Author: per1234

Diff for: arduino/libraries/loader_test.go

@@ -0,0 +1,68 @@
+// This file is part of arduino-cli.
+//
+// Copyright 2020 ARDUINO SA (http://www.arduino.cc/)
+//
+// This software is released under the GNU General Public License version 3,
+// which covers the main part of arduino-cli.
+// The terms of this license can be found at:
+// https://www.gnu.org/licenses/gpl-3.0.en.html
+//
+// You can be released from the requirements of the above licenses by purchasing
+// a commercial license. Buying such a license is mandatory if you want to
+// modify or otherwise use the software for commercial activities involving the
+// Arduino software without disclosing the source code of your own applications.
+// To purchase a commercial license, send an email to [email protected].
+
+package libraries
+
+import (
+	"os"
+	"testing"
+	"time"
+
+	paths "github.com/arduino/go-paths-helper"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestSymlinkLoop(t *testing.T) {
+	// Set up directory structure of test library.
+	libraryPath, err := paths.TempDir().MkTempDir("TestSymlinkLoop")
+	defer libraryPath.RemoveAll() // Clean up after the test.
+	require.Nil(t, err)
+	err = libraryPath.Join("TestSymlinkLoop.h").WriteFile([]byte{})
+	require.Nil(t, err)
+	examplesPath := libraryPath.Join("examples")
+	err = examplesPath.Mkdir()
+	require.Nil(t, err)
+
+	// It's probably most friendly for contributors using Windows to create the symlinks needed for the test on demand.
+	err = os.Symlink(examplesPath.Join("..").String(), examplesPath.Join("UpGoer1").String())
+	require.Nil(t, err, "This test must be run as administrator on Windows to have symlink creation privilege.")
+	// It's necessary to have multiple symlinks to a parent directory to create the loop.
+	err = os.Symlink(examplesPath.Join("..").String(), examplesPath.Join("UpGoer2").String())
+	require.Nil(t, err)
+
+	// The failure condition is Load() never returning, testing for which requires setting up a timeout.
+	done := make(chan bool)
+	go func() {
+		_, err = Load(libraryPath, User)
+		done <- true
+	}()
+
+	assert.Eventually(
+		t,
+		func() bool {
+			select {
+			case <-done:
+				return true
+			default:
+				return false
+			}
+		},
+		20*time.Second,
+		10*time.Millisecond,
+		"Infinite symlink loop while loading library",
+	)
+	require.Nil(t, err)
+}