docs(readme): fix document references in READMES && Add translation f…

…or unit test (#273)

* docs(readme): fix document references

Supplement the directory of the unit test, fix the reference path error of the document in the
associated preloading, and fix the format problem that there are no blank lines before and after
some sample codes

* docs(readme): fix document references

    Supplement the directory of the unit test, fix the reference path error of the document in the
    associated preloading in README.ZH-CN.md

* docs(readme): add translation for unit test

README.ZH_CN.md

@@ -116,6 +116,7 @@
           - [`Where` 子句](#where-clause)
           - [`Set` 子句](#set-clause)
         - [方法接口示例](#method-interface-example)
+      - [单元测试](#unit-test)
       - [智能选择字段](#smart-select-fields)
     - [高级教程](#advanced-topics)
       - [查询优化提示（Hints）](#hints)
@@ -1415,7 +1416,7 @@ type User struct {
 users, err := u.WithContext(ctx).Preload(field.Associations).Find()
 ```
 
-`clause.Associations` 不会加载嵌套关联, 嵌套关联加载可以用 [Nested Preloading](#nested_preloading) e.g:
+`clause.Associations` 不会加载嵌套关联, 嵌套关联加载可以用 [Nested Preloading](#nested-preloading) e.g:
 
 ```go
 users, err := u.WithContext(ctx).Preload(u.Orders.OrderItems.Product).Find()
@@ -1841,6 +1842,63 @@ type Method interface {
 }
 ```
 
+#### <span id="unit-test">单元测试</span>
+
+如果设置了 `WithUnitTest` 方法，就会生成单元测试文件，生成通用查询功能的单元测试代码。
+
+自定义方法的单元测试需要自定义对应的测试用例，它应该和测试文件放在同一个包里。
+
+一个测试用例包含输入和期望结果，输入应和对应的方法参数匹配，期望应和对应的方法返回值相匹配。这将在测试中被断言为 “**Equal（相等）**”。
+
+
+```go
+package query
+
+type Input struct {
+  Args []interface{}
+}
+
+type Expectation struct {
+  Ret []interface{}
+}
+
+type TestCase struct {
+  Input
+  Expectation
+}
+
+/* Table student */
+
+var StudentFindByIdTestCase = []TestCase {
+  {
+    Input{[]interface{}{1}},
+    Expectation{[]interface{}{nil, nil}},
+  },
+}
+```
+
+相应测试代码：
+
+```go
+//FindById select * from @@table where id = @id
+func (s studentDo) FindById(id int64) (result *model.Student, err error) {
+    ///
+}
+
+func Test_student_FindById(t *testing.T) {
+    student := newStudent(db)
+    do := student.WithContext(context.Background()).Debug()
+
+    for i, tt := range StudentFindByIdTestCase {
+        t.Run("FindById_"+strconv.Itoa(i), func(t *testing.T) {
+            res1, res2 := do.FindById(tt.Input.Args[0].(int64))
+            assert(t, "FindById", res1, tt.Expectation.Ret[0])
+            assert(t, "FindById", res2, tt.Expectation.Ret[1])
+        })
+    }
+}
+```
+
 #### <span id="smart-select-fields">智能选择字段</span>
 
 GEN 允许使用 `Select` 选择特定字段，如果你经常在应用程序中使用 ，也许你想为 API 使用定义一个更小的结构，它可以自动选择特定字段，例如：

README.md

@@ -117,6 +117,7 @@ A safer orm base on [GORM](https://github.com/go-gorm/gorm), aims to be develope
           - [`Where` clause](#where-clause)
           - [`Set` clause](#set-clause)
         - [Method interface example](#method-interface-example)
+      - [Unit Test](#unit-test)
       - [Smart select fields](#smart-select-fields)
     - [Advanced Topics](#advanced-topics)
       - [Hints](#hints)
@@ -1418,7 +1419,7 @@ type User struct {
 users, err := u.WithContext(ctx).Preload(field.Associations).Find()
 ```
 
-`clause.Associations` won’t preload nested associations, but you can use it with [Nested Preloading](#nested_preloading) together, e.g:
+`clause.Associations` won’t preload nested associations, but you can use it with [Nested Preloading](#nested-preloading) together, e.g:
 
 ```go
 users, err := u.WithContext(ctx).Preload(u.Orders.OrderItems.Product).Find()
@@ -1831,10 +1832,13 @@ type Method interface {
 ```
 
 #### Unit Test
+
 Unit test file will be generated if `WithUnitTest` is set, which will generate unit test for general query function.
+
 Unit test for DIY method need diy testcase, which should place in the same package with test file.
 
 A testcase contains input and expectation result, input should match the method arguments, expectation should match method return values, which will be asserted **Equal** in test.
+
 ```go
 package query
 
@@ -1859,9 +1863,10 @@ var StudentFindByIdTestCase = []TestCase {
     Expectation{[]interface{}{nil, nil}},
   },
 }
-
 ```
+
 Corresponding test
+
 ```go
 //FindById select * from @@table where id = @id
 func (s studentDo) FindById(id int64) (result *model.Student, err error) {