Example of basic unit test in Golang

Example Testing in Go

// running tests 
// go tool test2json -t /tmp/w4vqgd_p/T/GoLand/___go_test_temp_testing_go.test -test.v -test.paniconexit0

// example results
// === RUN   TestAddition
// --- PASS: TestAddition (0.00s)
// === RUN   TestBadMath
// --- PASS: TestBadMath (0.00s)
// === RUN   TestSubtraction
// --- PASS: TestSubtraction (0.00s)
// PASS

//in main.go
package main

import "errors"

func mather(a int, b int, o string)  (int, error){
	var x int
	var err error

	if o == "add"{
		x = a + b
	} else if o == "subtract"{
		x = a - b
	} else {
		err = errors.New("Input " + o + " is an unsupported operation")
	}

	return x, err

}

//in main_test.go
package main

import (
	"testing"
)

func TestAddition(t *testing.T){
	expected := 4
	actual, err := mather(2,2, "add")

	if expected != actual{
		t.Errorf("We expected %v and got %v", expected, actual)
	}

	if err != nil{
		t.Errorf("We got an error %v", err)
	}
}

func TestBadMath(t *testing.T)  {
	expected := "Input divide is an unsupported operation"
	actual, err := mather(100 , 2, "divide")
	if actual != 0{
		t.Errorf("This should have been 0, the nil of int returns %v", actual)
	}

	if err.Error() != expected{
		t.Errorf("We got an unexpected error %v is not %v", err.Error(), expected)
	}
}

func TestSubtraction(t *testing.T)  {
	expected := 98
	actual,err := mather(100 , 2, "subtract")
	if expected != actual{
		t.Errorf("We expected %v and got %v", expected, actual)
	}
	if err != nil{
		t.Errorf("We got an error %v", err)
	}
}