Writing basic tests in Go is:

  • creating a file with the suffix *_test.go
  • definig a function with the signature TestXxx(t *testing.T)
  • running it using the go test command
go mod init add
go mod tidy

// add.go
package add

func Add(a ...int) int {
  total := 0
  for i := range a {
    total += a[i]
  }
  return total
}

// add_test.go
package add

import "testing"

func TestAdd(t *testing.T) {
  // case 1
  if res := Add(1, 2, 3); res != 6 {
    t.Errorf("Expected %d instead of %d", 6, res)
  }

  // case 2
  if res := Add(-1, -2); res != -3 {
    t.Errorf("Expected %d instead of %d", -3, res)
  }
}

go test
go test -v # verbose mode
go test -v -- -test.run ^TestAdd$
go test -run ^TestAdd$ -v
go test -run "^TestAdd$" -v


Further info: