fs: Add --disable flag to disable optional features - fixes #1551

Eg to disable server side copy use `--disable copy`, to see a list of
what you can disable, `--disable help`.

fs/fs_test.go

@@ -0,0 +1,54 @@
+package fs
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestFeaturesDisable(t *testing.T) {
+	ft := new(Features)
+	ft.Copy = func(src Object, remote string) (Object, error) {
+		return nil, nil
+	}
+	ft.CaseInsensitive = true
+
+	assert.NotNil(t, ft.Copy)
+	assert.Nil(t, ft.Purge)
+	ft.Disable("copy")
+	assert.Nil(t, ft.Copy)
+	assert.Nil(t, ft.Purge)
+
+	assert.True(t, ft.CaseInsensitive)
+	assert.False(t, ft.DuplicateFiles)
+	ft.Disable("caseinsensitive")
+	assert.False(t, ft.CaseInsensitive)
+	assert.False(t, ft.DuplicateFiles)
+}
+
+func TestFeaturesList(t *testing.T) {
+	ft := new(Features)
+	names := strings.Join(ft.List(), ",")
+	assert.True(t, strings.Contains(names, ",Copy,"))
+}
+
+func TestFeaturesDisableList(t *testing.T) {
+	ft := new(Features)
+	ft.Copy = func(src Object, remote string) (Object, error) {
+		return nil, nil
+	}
+	ft.CaseInsensitive = true
+
+	assert.NotNil(t, ft.Copy)
+	assert.Nil(t, ft.Purge)
+	assert.True(t, ft.CaseInsensitive)
+	assert.False(t, ft.DuplicateFiles)
+
+	ft.DisableList([]string{"copy", "caseinsensitive"})
+
+	assert.Nil(t, ft.Copy)
+	assert.Nil(t, ft.Purge)
+	assert.False(t, ft.CaseInsensitive)
+	assert.False(t, ft.DuplicateFiles)
+}