# Unit Testing
Unit testing allows us to test a `http.HandlerFunc` directly withoutrunning any middleware, routers, or any other type of code that mightotherwise wrap the function.
~~~
package main
import (
"fmt"
"net/http"
)
func HelloWorld(res http.ResponseWriter, req *http.Request) {
fmt.Fprint(res, "Hello World")
}
func main() {
http.HandleFunc("/", HelloWorld)
http.ListenAndServe(":3000", nil)
}
~~~
This is the test file. It should be placed in the same directory asyour application and name `main_test.go`.
~~~
package main
import (
"net/http"
"net/http/httptest"
"testing"
)
func Test_HelloWorld(t *testing.T) {
req, err := http.NewRequest("GET", "http://example.com/foo", nil)
if err != nil {
t.Fatal(err)
}
res := httptest.NewRecorder()
HelloWorld(res, req)
exp := "Hello World"
act := res.Body.String()
if exp != act {
t.Fatalf("Expected %s gog %s", exp, act)
}
}
~~~
## Exercises
1. Change the output of `HelloWorld` to print a parameter and then test that the parameter is rendered.
1. Create a POST request and test that the request is properly handled.
- Introduction
- 1. Go Makes Things Simple
- 2. The net/http package
- 3. Creating a Basic Web App
- 4. Deployment
- 5. URL Routing
- 6. Middleware
- 7. Rendering
- JSON
- HTML Templates
- Using The render package
- 8. Testing
- Unit Testing
- End to End Testing
- 9. Controllers
- 10. Databases
- 11. Tips and Tricks
- 12. Moving Forward