Testing a Go program?

Question

go

Good afternoon!
I have written a web service in Go and am writing tests for it. I wrote a test to test the handler but I get an error

package main

import (
  "net/http"
  "net/http/httptest"
  "testing"

)

func TestHealthCheckHandler(t *testing.T) {

  req, err := http.NewRequest("POST", "/ad/getall", nil)
  if err != nil {
    t.Fatal(err)
  }

  rr := httptest.NewRecorder()
  handler := http.HandlerFunc(GetAll)


  handler.ServeHTTP(rr, req)


  expected := `400`
  if rr.Body.String() != expected {
    t.Errorf("handler returned unexpected body: got %v want %v",
      rr.Body.String(), expected)
  }
}

Answer 1

The test is written correctly. But the main program, apparently, no. Give the text of main.go.
Well, or look at line No. 80 in it, as the execution stack dump writes.