add support to make map separator configurable

mapper_test.go

@@ -161,6 +161,16 @@ func TestMapWithMultipleValues(t *testing.T) {
 	require.Equal(t, map[string]string{"a": "b", "c": "d"}, cli.Value)
 }
 
+func TestMapWithDifferentSeparator(t *testing.T) {
+	var cli struct {
+		Value map[string]string `mapsep:","`
+	}
+	k := mustNew(t, &cli)
+	_, err := k.Parse([]string{"--value=a=b,c=d"})
+	require.NoError(t, err)
+	require.Equal(t, map[string]string{"a": "b", "c": "d"}, cli.Value)
+}
+
 func TestURLMapper(t *testing.T) {
 	var cli struct {
 		URL *url.URL `arg:""`