英文:
How to write unit test failure for json.NewDecoder.Decode?
问题
我必须为一个函数编写单元测试，而这个函数使用了json.NewDecoder.Decode。
var infos models.RegisterInfos // 带有json字段的结构体err := json.NewDecoder(r.Body).Decode(&infos)if err != nil {// 处理错误}
在单元测试中（使用testing包），如何模拟json.NewDecoder(r.Body).Decode(&infos)的错误？我尝试查看NewDecoder和Decode的源代码，但是我找不到可以在几行代码中生成错误的内容。
英文:
I have to write unit tests for a function and this function uses json.NewDecoder.Decode
var infos models.RegisterInfos // struct with json fieldserr := json.NewDecoder(r.Body).Decode(&infos)if err != nil {// do something}
How can I simulate an error in a unit test (using the testing package) for json.NewDecoder(r.Body).Decode(&infos) ? I tried looking in the NewDecoder and Decode source code but I couldn't find anything that can generate an error in just a few lines.
答案1
得分: 1
你可以发送一个类似<invalid json>的主体作为示例：
func main() {body := "<invalid json>"var infos RegisterInfos // 带有 JSON 字段的结构体err := json.NewDecoder(strings.NewReader(body)).Decode(&infos)if err != nil {fmt.Println(err)}}
请参阅 https://go.dev/play/p/44E99D0eQou
英文:
you could send a body like <invalid json> as example:
func main() {body := "<invalid json>"var infos RegisterInfos // struct with json fieldserr := json.NewDecoder(strings.NewReader(body)).Decode(&infos)if err != nil {fmt.Println(err)}}
答案2
得分: 1
将其输入无效输入或解码为无效输出：
package mainimport ("encoding/json""fmt""strings""testing")type Message struct {Name string}func TestDecodeFail(t *testing.T) {for _, tc := range []struct {in stringdesc stringout any}{{`{Name: "Bobby"}`, "key without quotes", &Message{}},{`{"Name": "Foo"a}`, "extra character", &Message{}},{`{"Name": "Foo"}`, "bad destination", &struct{ Name int64 }{}},{`{"Name": "Foo\u001a"}`, "invalid character", &Message{}},{`{"Name": "Foo"}`, "unmarshal to nil", (*Message)(nil)},} {err := decode(tc.in, tc.out)if err != nil {fmt.Printf("%s -> %s, %T\n", tc.desc, err.Error(), err)}}}func decode(in string, out any) error {return json.NewDecoder(strings.NewReader(in)).Decode(out)}
输出：
key without quotes -> invalid character 'N' looking for beginning of object key string, *json.SyntaxErrorextra character -> invalid character 'a' after object key:value pair, *json.SyntaxErrorbad destination -> json: cannot unmarshal string into Go struct field .Name of type int64, *json.UnmarshalTypeErrorinvalid character -> invalid character '\x1a' in string literal, *json.SyntaxErrorunmarshal to nil -> json: Unmarshal(nil *main.Message), *json.InvalidUnmarshalError
英文:
Feed it an invalid input, or decode into an invalid output:
package mainimport ("encoding/json""fmt""strings""testing")type Message struct {Name string}func TestDecodeFail(t *testing.T) {for _, tc := range []struct {in stringdesc stringout any}{{`{Name: "Bobby"}`, "key without quotes", &Message{}},{`{"Name": "Foo"a}`, "extra character", &Message{}},{`{"Name": "Foo"}`, "bad destination", &struct{ Name int64 }{}},{`{"Name": "Foo` + "\u001a" + `"}`, "invalid character", &Message{}},{`{"Name": "Foo"}`, "unmarshal to nil", (*Message)(nil)},} {err := decode(tc.in, tc.out)if err != nil {fmt.Printf("%s -> %s, %T\n", tc.desc, err.Error(), err)}}}func decode(in string, out any) error {return json.NewDecoder(strings.NewReader(in)).Decode(out)}
Outputs:
key without quotes -> invalid character 'N' looking for beginning of object key string, *json.SyntaxErrorextra character -> invalid character 'a' after object key:value pair, *json.SyntaxErrorbad destination -> json: cannot unmarshal string into Go struct field .Name of type int64, *json.UnmarshalTypeErrorinvalid character -> invalid character '\x1a' in string literal, *json.SyntaxErrorunmarshal to nil -> json: Unmarshal(nil *main.Message), *json.InvalidUnmarshalError
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