refactored so there would be one IsNonEmptyDir check instead of an IsDir check and an IsEmptyDir check

cmd/dep/ensure.go

@@ -223,17 +223,11 @@ func (cmd *ensureCommand) Run(ctx *dep.Ctx, args []string) error {
 
 	// check if vendor exists, because if the locks are the same but
 	// vendor does not exist we should write vendor
-	var writeV bool
-	path := filepath.Join(sw.Root, "vendor")
-	vendorIsDir, err := dep.IsDir(path)
+	vendorExists, err := dep.IsNonEmptyDir(filepath.Join(sw.Root, "vendor"))
 	if err != nil {
 		return errors.Wrap(err, "ensure vendor is a directory")
 	}
-	vendorEmpty, _ := dep.IsEmptyDir(path)
-	vendorExists := vendorIsDir && !vendorEmpty
-	if !vendorExists && solution != nil {
-		writeV = true
-	}
+	writeV := !vendorExists && solution != nil
 
 	return errors.Wrap(sw.WriteAllSafe(writeV), "grouped write of manifest, lock and vendor")
 }

fs.go

@@ -45,12 +45,17 @@ func IsDir(name string) (bool, error) {
 	return true, nil
 }
 
-func IsEmptyDir(name string) (bool, error) {
+func IsNonEmptyDir(name string) (bool, error) {
+	isDir, err := IsDir(name)
+	if !isDir || err != nil {
+		return isDir, err
+	}
+
 	files, err := ioutil.ReadDir(name)
 	if err != nil {
 		return false, err
 	}
-	return len(files) == 0, nil
+	return len(files) != 0, nil
 }
 
 func writeFile(path string, in json.Marshaler) error {

fs_test.go

@@ -192,15 +192,15 @@ func TestIsEmpty(t *testing.T) {
 	h := test.NewHelper(t)
 	h.TempDir("empty")
 	tests := map[string]string{
-		wd:                                                  "false",
-		"_testdata":                                         "false",
-		filepath.Join(wd, "main.go"):                        "err",
-		filepath.Join(wd, "this_file_does_not_exist.thing"): "err",
-		h.Path("empty"):                                     "true",
+		wd:                                                  "true",
+		"_testdata":                                         "true",
+		filepath.Join(wd, "fs.go"):                          "err",
+		filepath.Join(wd, "this_file_does_not_exist.thing"): "false",
+		h.Path("empty"):                                     "false",
 	}
 
 	for f, want := range tests {
-		empty, err := IsEmptyDir(f)
+		empty, err := IsNonEmptyDir(f)
 		if want == "err" {
 			if err == nil {
 				t.Fatalf("Wanted an error for %v, but it was nil", f)