Unit Testing

Unit testing allows us to test a http.HandlerFunc directly without
running any middleware, routers, or any other type of code that might
otherwise wrap the function.

  1. package main
  3. import (
  4.     "fmt"
  5.     "net/http"
  6. )
  8. func HelloWorld(res http.ResponseWriter, req *http.Request) {
  9.     fmt.Fprint(res, "Hello World")
  10. }
  12. func main() {
  13.     http.HandleFunc("/", HelloWorld)
  14.     http.ListenAndServe(":3000", nil)
  15. }

This is the test file. It should be placed in the same directory as
your application and name main_test.go.

  1. package main
  3. import (
  4.     "net/http"
  5.     "net/http/httptest"
  6.     "testing"
  7. )
  9. func Test_HelloWorld(t *testing.T) {
  10.     req, err := http.NewRequest("GET", "http://example.com/foo", nil)
  11.     if err != nil {
  12.         t.Fatal(err)
  13.     }
  15.     res := httptest.NewRecorder()
  16.     HelloWorld(res, req)
  18.     exp := "Hello World"
  19.     act := res.Body.String()
  20.     if exp != act {
  21.         t.Fatalf("Expected %s gog %s", exp, act)
  22.     }
  23. }

Exercises

  1. Change the output of HelloWorld to print a parameter and then test that the parameter is rendered.
  2. Create a POST request and test that the request is properly handled.