tests: add tests for wait-paths (#1384)

Follow up PR to add tests for wait-paths after initial PR #1258
was merged.

Signed-off-by: Maksim An <maksiman@microsoft.com>

cmd/hooks/wait-paths/main.go

@@ -1,9 +1,8 @@
-// +build linux
-
 package main
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"os"
 	"strings"
@@ -18,10 +17,20 @@ const (
 	timeoutFlag = "timeout"
 )
 
+var errEmptyPaths = errors.New("paths cannot be empty")
+
 // This is a hook that waits for a specific path to appear.
 // The hook has required list of comma-separated paths and a default timeout in seconds.
 
 func main() {
+	app := newCliApp()
+	if err := app.Run(os.Args); err != nil {
+		logrus.Fatalf("%s\n", err)
+	}
+	os.Exit(0)
+}
+
+func newCliApp() *cli.App {
 	app := cli.NewApp()
 	app.Name = "wait-paths"
 	app.Usage = "Provide a list paths and an optional timeout"
@@ -38,14 +47,16 @@ func main() {
 		},
 	}
 	app.Action = run
-	if err := app.Run(os.Args); err != nil {
-		logrus.Fatalf("%s\n", err)
-	}
-	os.Exit(0)
+	return app
 }
 
 func run(cCtx *cli.Context) error {
 	timeout := cCtx.GlobalInt(timeoutFlag)
+
+	pathsVal := cCtx.GlobalString(pathsFlag)
+	if pathsVal == "" {
+		return errEmptyPaths
+	}
 	paths := strings.Split(cCtx.GlobalString(pathsFlag), ",")
 
 	waitCtx, cancel := context.WithTimeout(context.Background(), time.Duration(timeout)*time.Second)
@@ -59,7 +70,7 @@ func run(cCtx *cli.Context) error {
 				}
 				select {
 				case <-waitCtx.Done():
-					return fmt.Errorf("timeout while waiting for path %q to appear", path)
+					return fmt.Errorf("timeout while waiting for path %q to appear: %w", path, context.DeadlineExceeded)
 				default:
 					time.Sleep(time.Millisecond * 10)
 					continue

cmd/hooks/wait-paths/wait_paths_test.go

@@ -0,0 +1,133 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"math"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+)
+
+func Test_Paths_EmptyString_NotAllowed(t *testing.T) {
+	args := []string{
+		"wait-paths",
+		"-p",
+		"",
+	}
+	app := newCliApp()
+	err := app.Run(args)
+	if !errors.Is(err, errEmptyPaths) {
+		t.Fatalf("expected 'cannot be empty' error, got: %s", err)
+	}
+}
+
+func Test_InvalidWaitPath_DefaultTimeout(t *testing.T) {
+	args := []string{
+		"wait-paths",
+		"-p",
+		"non-existent",
+	}
+	app := newCliApp()
+	err := app.Run(args)
+	if cause := errors.Unwrap(err); !errors.Is(cause, context.DeadlineExceeded) {
+		t.Fatalf("expected 'timeout error', got: %s", err)
+	}
+}
+
+func Test_InvalidWaitPath_5SecondTimeout(t *testing.T) {
+	args := []string{
+		"wait-paths",
+		"-p",
+		"non-existent",
+		"-t",
+		"5",
+	}
+	app := newCliApp()
+	start := time.Now()
+	err := app.Run(args)
+	if cause := errors.Unwrap(err); !errors.Is(cause, context.DeadlineExceeded) {
+		t.Fatalf("expected 'timeout error', got: %s", err)
+	}
+
+	end := time.Now()
+	diff := end.Sub(start)
+	diffSeconds := math.Round(diff.Seconds())
+	if diffSeconds != 5 {
+		t.Fatalf("expected 5 second timeout, got: %f", diffSeconds)
+	}
+}
+
+func Test_Valid_Paths_AlreadyPresent(t *testing.T) {
+	tmpDir := t.TempDir()
+	var files []string
+	for _, name := range []string{"file1", "file2"} {
+		filePath := filepath.Join(tmpDir, name)
+		if f, err := os.Create(filePath); err != nil {
+			t.Fatalf("failed to create temporary file %s: %s", name, err)
+		} else {
+			_ = f.Close()
+		}
+		files = append(files, filePath)
+	}
+	pathsArg := strings.Join(files, ",")
+
+	args := []string{
+		"wait-paths",
+		"-p",
+		pathsArg,
+	}
+	app := newCliApp()
+	if err := app.Run(args); err != nil {
+		t.Fatalf("expected no error, got: %s", err)
+	}
+}
+
+func Test_Valid_Paths_BecomeAvailableLater(t *testing.T) {
+	tmpDir := t.TempDir()
+	var files []string
+	for _, name := range []string{"file1", "file2"} {
+		files = append(files, filepath.Join(tmpDir, name))
+	}
+	pathsArg := strings.Join(files, ",")
+
+	errChan := make(chan error)
+	var wg sync.WaitGroup
+	defer func() {
+		wg.Wait()
+		close(errChan)
+	}()
+
+	args := []string{
+		"wait-paths",
+		"-p",
+		pathsArg,
+	}
+	app := newCliApp()
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		errChan <- app.Run(args)
+	}()
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		time.Sleep(5 * time.Second)
+		for _, fileName := range files {
+			if f, err := os.Create(fileName); err != nil {
+				errChan <- err
+				return
+			} else {
+				_ = f.Close()
+			}
+		}
+	}()
+
+	if err := <-errChan; err != nil {
+		t.Fatalf("expected no error, got: %s", err)
+	}
+}