Parse empty string as an empty slice of numbers (#119)

envconfig.go

@@ -298,12 +298,15 @@ func processField(value string, field reflect.Value) error {
 		}
 		field.SetFloat(val)
 	case reflect.Slice:
-		vals := strings.Split(value, ",")
-		sl := reflect.MakeSlice(typ, len(vals), len(vals))
-		for i, val := range vals {
-			err := processField(val, sl.Index(i))
-			if err != nil {
-				return err
+		sl := reflect.MakeSlice(typ, 0, 0)
+		if len(strings.TrimSpace(value)) != 0 {
+			vals := strings.Split(value, ",")
+			sl = reflect.MakeSlice(typ, len(vals), len(vals))
+			for i, val := range vals {
+				err := processField(val, sl.Index(i))
+				if err != nil {
+					return err
+				}
 			}
 		}
 		field.Set(sl)

envconfig_test.go

@@ -43,6 +43,7 @@ type Specification struct {
 	Timeout                      time.Duration
 	AdminUsers                   []string
 	MagicNumbers                 []int
+	EmptyNumbers                 []int
 	ColorCodes                   map[string]int
 	MultiWordVar                 string
 	MultiWordVarWithAutoSplit    uint32 `split_words:"true"`
@@ -93,6 +94,7 @@ func TestProcess(t *testing.T) {
 	os.Setenv("ENV_CONFIG_TIMEOUT", "2m")
 	os.Setenv("ENV_CONFIG_ADMINUSERS", "John,Adam,Will")
 	os.Setenv("ENV_CONFIG_MAGICNUMBERS", "5,10,20")
+	os.Setenv("ENV_CONFIG_EMPTYNUMBERS", "")
 	os.Setenv("ENV_CONFIG_COLORCODES", "red:1,green:2,blue:3")
 	os.Setenv("SERVICE_HOST", "127.0.0.1")
 	os.Setenv("ENV_CONFIG_TTL", "30")
@@ -146,6 +148,9 @@ func TestProcess(t *testing.T) {
 		s.MagicNumbers[2] != 20 {
 		t.Errorf("expected %#v, got %#v", []int{5, 10, 20}, s.MagicNumbers)
 	}
+	if len(s.EmptyNumbers) != 0 {
+		t.Errorf("expected %#v, got %#v", []int{}, s.EmptyNumbers)
+	}
 	if s.Ignored != "" {
 		t.Errorf("expected empty string, got %#v", s.Ignored)
 	}

testdata/custom.txt

@@ -11,6 +11,7 @@ ENV_CONFIG_TTL=
 ENV_CONFIG_TIMEOUT=
 ENV_CONFIG_ADMINUSERS=
 ENV_CONFIG_MAGICNUMBERS=
+ENV_CONFIG_EMPTYNUMBERS=
 ENV_CONFIG_COLORCODES=
 ENV_CONFIG_MULTIWORDVAR=
 ENV_CONFIG_MULTI_WORD_VAR_WITH_AUTO_SPLIT=

testdata/default_list.txt

@@ -66,6 +66,11 @@ ENV_CONFIG_MAGICNUMBERS
 ..[type]........Comma-separated.list.of.Integer
 ..[default].....
 ..[required]....
+ENV_CONFIG_EMPTYNUMBERS
+..[description].
+..[type]........Comma-separated.list.of.Integer
+..[default].....
+..[required]....
 ENV_CONFIG_COLORCODES
 ..[description].
 ..[type]........Comma-separated.list.of.String:Integer.pairs

testdata/default_table.txt

@@ -15,6 +15,7 @@ ENV_CONFIG_TTL...................................Unsigned.Integer...............
 ENV_CONFIG_TIMEOUT...............................Duration..........................................................................
 ENV_CONFIG_ADMINUSERS............................Comma-separated.list.of.String....................................................
 ENV_CONFIG_MAGICNUMBERS..........................Comma-separated.list.of.Integer...................................................
+ENV_CONFIG_EMPTYNUMBERS..........................Comma-separated.list.of.Integer...................................................
 ENV_CONFIG_COLORCODES............................Comma-separated.list.of.String:Integer.pairs......................................
 ENV_CONFIG_MULTIWORDVAR..........................String............................................................................
 ENV_CONFIG_MULTI_WORD_VAR_WITH_AUTO_SPLIT........Unsigned.Integer..................................................................