Support -flag=var1,var2,var3 to fix #2332

helper/flag-slice/flag.go

@@ -11,6 +11,6 @@ func (s *StringFlag) String() string {
 }
 
 func (s *StringFlag) Set(value string) error {
-	*s = append(*s, value)
+	*s = append(*s, strings.Split(value, ",")...)
 	return nil
 }

helper/flag-slice/flag_test.go

@@ -14,6 +14,8 @@ func TestStringFlag_implements(t *testing.T) {
 	}
 }
 
+// TestStringFlagSet tests for setting the same flag more than once on the CLI
+// like: blah -flag foo -flag bar
 func TestStringFlagSet(t *testing.T) {
 	sv := new(StringFlag)
 	err := sv.Set("foo")
@@ -31,3 +33,18 @@ func TestStringFlagSet(t *testing.T) {
 		t.Fatalf("Bad: %#v", sv)
 	}
 }
+
+// TestMultiStringFlag tests for setting the same flag using a comma-separated
+// list of items like: blah -flag=foo,bar
+func TestMultiStringFlag(t *testing.T) {
+	sv := new(StringFlag)
+	err := sv.Set("chocolate,vanilla")
+	if err != nil {
+		t.Fatalf("err :%s", err)
+	}
+
+	expected := []string{"chocolate", "vanilla"}
+	if !reflect.DeepEqual([]string(*sv), expected) {
+		t.Fatalf("Expected: %#v, found: %#v", expected, sv)
+	}
+}