How to test code using JSON in Golang?

Testing code that uses JSON in Go is crucial, and this article provides the following steps: Write JSON data, encoding to byte slices using json.Marshal. Decode JSON data, parsing from byte slice to struct using json.Unmarshal.

How to test code that uses JSON in Golang

Testing code that uses JSON in Golang is important to ensure the robustness of the application Sex is crucial. This article will guide you through the following steps for testing:

1. Write JSON data

import (
    "encoding/json"
    "fmt"
    "testing"
)

type Person struct {
    Name string `json:"name"`
    Age  int    `json:"age"`
}

func TestEncodeJSON(t *testing.T) {
    person := Person{Name: "John", Age: 30}

    b, err := json.Marshal(person)
    if err != nil {
        t.Errorf("Error encoding JSON: %v", err)
    }

    expected := `{"name":"John","age":30}`
    if string(b) != expected {
        t.Errorf("Expected '%s', got '%s'", expected, string(b))
    }
}

2. Decode JSON data

func TestDecodeJSON(t *testing.T) {
    jsonStr := `{"name":"Mary","age":25}`

    person := Person{}
    err := json.Unmarshal([]byte(jsonStr), &person)
    if err != nil {
        t.Errorf("Error decoding JSON: %v", err)
    }

    expected := Person{Name: "Mary", Age: 25}
    if person != expected {
        t.Errorf("Expected '%v', got '%v'", expected, person)
    }
}

Practical case

Consider a function that reads a JSON configuration file:

func LoadConfig(path string) (Config, error) {
    b, err := ioutil.ReadFile(path)
    if err != nil {
        return Config{}, err
    }

    config := Config{}
    err = json.Unmarshal(b, &config)
    if err != nil {
        return Config{}, err
    }

    return config, nil
}

The following test case will verify whether the LoadConfig function reads correctly JSON file:

func TestLoadConfig(t *testing.T) {
    // 创建一个包含 JSON 数据的临时文件
    f, err := ioutil.TempFile("", "config")
    if err != nil {
        t.Errorf("Error creating temporary file: %v", err)
    }
    defer os.Remove(f.Name())

    _, err = f.WriteString(`{"key":"value"}`)
    if err != nil {
        t.Errorf("Error writing to temporary file: %v", err)
    }
    if err := f.Close(); err != nil {
        t.Errorf("Error closing temporary file: %v", err)
    }

    config, err := LoadConfig(f.Name())
    if err != nil {
        t.Errorf("Error loading config: %v", err)
    }

    expected := Config{Key: "value"}
    if config != expected {
        t.Errorf("Expected '%v', got '%v'", expected, config)
    }
}

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