Update required error message (#144)

Author: cristaloleg

aconfig.go

@@ -270,13 +270,11 @@ func (l *Loader) checkRequired() error {
 			missedFields = append(missedFields, field.name)
 		}
 	}
+
 	if len(missedFields) == 0 {
 		return nil
 	}
-	if len(missedFields) == 1 {
-		return fmt.Errorf("field %s is required but not set", missedFields[0])
-	}
-	return fmt.Errorf("fields %s are required but not set", strings.Join(missedFields, ","))
+	return fmt.Errorf("fields required but not set: %s", strings.Join(missedFields, ","))
 }
 
 func (l *Loader) loadDefaults() error {

aconfig_test.go

@@ -1096,12 +1096,13 @@ func TestMissingFieldWithRequiredTag(t *testing.T) {
 	})
 
 	err := loader.Load()
+	want := "load config: fields required but not set: Field1"
 
-	want := "load config: field Field1 is required but not set"
-	if err.Error() != want {
+	if have := err.Error(); have != want {
 		t.Fatalf("got %v, want %v", err, want)
 	}
 }
+
 func TestMissingFieldsWithRequiredTag(t *testing.T) {
 	cfg := struct {
 		Field1 string `required:"true"`
@@ -1112,9 +1113,9 @@ func TestMissingFieldsWithRequiredTag(t *testing.T) {
 	})
 
 	err := loader.Load()
+	want := "load config: fields required but not set: Field1,Field2"
 
-	want := "load config: fields Field1,Field2 are required but not set"
-	if err.Error() != want {
+	if have := err.Error(); have != want {
 		t.Fatalf("got %v, want %v", err, want)
 	}
 }