Table of Contents

• Basics of testing
• How test files are treated within a package

Basics of testing tutorial

• _test.go files are considered as tests.

import "testing"

func TextXxx(t *testing.T) {
    t.Errorf("Failed! %d", 10)
}
func BenchmarkXxx(b *testing.B)
func ExampleXxx()

func TestMain(m *testing.M) {
    // setup
    code := m.Run()
    // teardown
    os.Exit(code)
}

How test files are treated within a package dicussion

• _test.go files are not part of the package ordinarily built by go build but are a part of it when built by go test.
• You can use a different package name in _test.go files.
• For example, in a file foo/abc_test.go, you can declare a name like package foo_test, not package foo, so the file belong to a separated package foo_test.

You exploit this characteristic to expose internal functions for testing. For example:

package foo

// `doSomething` is defined in some other normal file and it is intended to use internally.
// However, if you want to use this internal function in an external package for testing,
// You can expose it only for testing as follows.
// Since the line is declared in `_test.go` file, it is exposed only during testing.
var DoSomething = doSomething