Optimize model naming (#910)

* add unit test

* fix #907

* format code

* format code

* format code

Co-authored-by: anqiansong <anqiansong@xiaoheiban.cn>

tools/goctl/util/string_test.go

@@ -0,0 +1,66 @@
+package util
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type data struct {
+	input    string
+	expected string
+}
+
+func TestTitle(t *testing.T) {
+	list := []*data{
+		{input: "_", expected: "_"},
+		{input: "abc", expected: "Abc"},
+		{input: "ABC", expected: "ABC"},
+		{input: "", expected: ""},
+		{input: " abc", expected: " abc"},
+	}
+	for _, e := range list {
+		assert.Equal(t, e.expected, Title(e.input))
+	}
+}
+
+func TestUntitle(t *testing.T) {
+	list := []*data{
+		{input: "_", expected: "_"},
+		{input: "Abc", expected: "abc"},
+		{input: "ABC", expected: "aBC"},
+		{input: "", expected: ""},
+		{input: " abc", expected: " abc"},
+	}
+
+	for _, e := range list {
+		assert.Equal(t, e.expected, Untitle(e.input))
+	}
+}
+
+func TestIndex(t *testing.T) {
+	list := []string{"a", "b", "c"}
+	assert.Equal(t, 1, Index(list, "b"))
+	assert.Equal(t, -1, Index(list, "d"))
+}
+
+func TestSafeString(t *testing.T) {
+	list := []*data{
+		{input: "_", expected: "_"},
+		{input: "a-b-c", expected: "a_b_c"},
+		{input: "123abc", expected: "_123abc"},
+		{input: "汉abc", expected: "_abc"},
+		{input: "汉a字", expected: "_a_"},
+		{input: "キャラクターabc", expected: "______abc"},
+		{input: "-a_B-C", expected: "_a_B_C"},
+		{input: "a_B C", expected: "a_B_C"},
+		{input: "A#B#C", expected: "A_B_C"},
+		{input: "_123", expected: "_123"},
+		{input: "", expected: ""},
+		{input: "\t", expected: "_"},
+		{input: "\n", expected: "_"},
+	}
+	for _, e := range list {
+		assert.Equal(t, e.expected, SafeString(e.input))
+	}
+}