fs: Document that Purger returns error on empty directory, test and fix

fs/fs.go

@@ -85,7 +85,7 @@ type Fs interface {
 
 	// Remove the directory (container, bucket) if empty
 	//
-	// Return an error if it doesn't exists or isn't empty
+	// Return an error if it doesn't exist or isn't empty
 	Rmdir() error
 
 	// Precision of the ModTimes in this Fs
@@ -135,6 +135,8 @@ type Purger interface {
 	//
 	// Implement this if you have a way of deleting all the files
 	// quicker than just running Remove() on the result of List()
+	//
+	// Return an error if it doesn't exist
 	Purge() error
 }
 

fstest/fstest.go

@@ -161,9 +161,12 @@ func RandomRemote(remoteName string, subdir bool) (fs.Fs, func()) {
 	}
 
 	finalise := func() {
-		TestPurge(remote)
+		_ = fs.Purge(remote) // ignore error
 		if parentRemote != nil {
-			TestPurge(parentRemote)
+			err = fs.Purge(parentRemote) // ignore error
+			if err != nil {
+				log.Printf("Failed to purge %v: %v", parentRemote, err)
+			}
 		}
 		// Delete directory if we made one above
 		if rmdir != "" {

fstest/fstests/fstests.go

@@ -322,7 +322,10 @@ func TestObjectRemove(t *testing.T) {
 func TestObjectPurge(t *testing.T) {
 	skipIfNotOk(t)
 	fstest.TestPurge(remote)
-	fstest.TestPurge(remote)
+	err := fs.Purge(remote)
+	if err == nil {
+		t.Fatal("Expecting error after on second purge")
+	}
 }
 
 func TestFinalise(t *testing.T) {

local/local.go

@@ -261,6 +261,13 @@ func (f *FsLocal) readPrecision() (precision time.Duration) {
 // deleting all the files quicker than just running Remove() on the
 // result of List()
 func (f *FsLocal) Purge() error {
+	fi, err := os.Lstat(f.root)
+	if err != nil {
+		return err
+	}
+	if !fi.Mode().IsDir() {
+		return fmt.Errorf("Can't Purge non directory: %q", f.root)
+	}
 	return os.RemoveAll(f.root)
 }