Standard package for Go unit testing: package testing

Package testing has in standard library since 2009. Convention of writing unit test in Go lang is: In file foo.go, will have file foo_test.go in same directory/folder. In file foo.go has method BlaBla(), and in foo_test.go has method TestBlaBla() accordingly.

I have file div.go has content

package table import ( "errors" "fmt"
) func Divide(x, y int8) (*string, error) { if y == 0 { return nil, errors.New("cannot divide by 0") } r := float64(x) / float64(y) result := fmt.Sprintf("%.2f", r) return &result, nil
}

For unit testing, has file div_test.go has content

package table_test import ( "errors" "testing" "github.com/donhuvy/Test-Driven-Development-in-Go/chapter04/table" "github.com/stretchr/testify/assert"
) func TestDivide(t *testing.T) { tests := map[string]struct { x, y int wantErr error want string }{ "pos x, pos y": {x: 8, y: 4, want: "2.00"}, "neg x, neg y": {x: -4, y: -8, want: "0.50"}, "equal x, y": {x: 4, y: 4, want: "1.00"}, "max x, pos y": {x: 127, y: 2, want: "63.50"}, "min x, pos y": {x: -128, y: 2, want: "-64.00"}, "zero x, pos y": {x: 0, y: 2, want: "0.00"}, "pos x, zero y": {x: 10, y: 0, wantErr: errors.New("cannot divide by 0")}, "zero x, zero y": {x: 0, y: 0, wantErr: errors.New("cannot divide by 0")}, "max x, max y": {x: 127, y: 127, want: "1.00"}, "min x, min y": {x: -128, y: -128, want: "1.00"}, } for name, rtc := range tests { tc := rtc t.Run(name, func(t *testing.T) { t.Parallel() x, y := int8(tc.x), int8(tc.y) r, err := table.Divide(x, y) if tc.wantErr != nil { assert.Equal(t, tc.wantErr, err) return } assert.Nil(t, err) assert.Equal(t, tc.want, *r) }) }
}

In this example, I used only Go standard library (supported by package testing).

Run unit testing with verbose information

Command for unit test running

firerose@firerose-desktop:~/Documents/github/Test-Driven-Development-in-Go$ go test -run TestDivide ./chapter04/table/ -v

Result

 --- PASS: TestDivide/max_x,_pos_y (0.00s) --- PASS: TestDivide/pos_x,_pos_y (0.00s) --- PASS: TestDivide/pos_x,_zero_y (0.00s) --- PASS: TestDivide/zero_x,_zero_y (0.00s) --- PASS: TestDivide/zero_x,_pos_y (0.00s) --- PASS: TestDivide/max_x,_max_y (0.00s) --- PASS: TestDivide/neg_x,_neg_y (0.00s) --- PASS: TestDivide/equal_x,_y (0.00s)
PASS
ok github.com/donhuvy/Test-Driven-Development-in-Go/chapter04/table 0.002s

*testing.Parallel() create parallel flows for unit testing in concurrency.

Third-party library support Go lang unit testing

With supporting from package github.com/strectchr/testify , *assert.Nil() for assertion Nil value. *assert.Equal() for assertion of equalitation.

assert.Equal receive 3 parameters likes this, one and first parameter is *testing , 2 next parameters are variable and value of variable:

assert.Equal(t, tc.wantErr, err)

assert.Nil() receive 2 parameters likes this

assert.Nil(t, err)

Third-party libraries support Go lang unit testing

• Testify: https://github.com/stretchr/testify (as mentioned above)
• Mockery https://github.com/vektra/mockery Generate skeleton/simple source code for Go lang unit testing. On top of generated files, has comment header

// Code generated by mockery v2.26.1. DO NOT EDIT.

In source code, you don't see declaring mockery in go.mod , it is tool installed to host machine.

Comand set Go to path

firerose@firerose-desktop:~/Downloads/go/bin$ pwd
/home/firerose/Downloads/go/bin
firerose@firerose-desktop:~/Downloads/go/bin$ export PATH=/home/firerose/Downloads/go/bin:$PATH
firerose@firerose-desktop:~/Downloads/go/bin$ echo $PATH
/home/firerose/Downloads/go/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/snap/bin
firerose@firerose-desktop:~/Downloads/go/bin$ go version
go version go1.20.4 linux/amd64
firerose@firerose-desktop:~/Downloads/go/bin$ 

Install Mockery by command

go install github.com/vektra/mockery/v2@v2.26.1