Write unit test in Golang

Friday, 12/05/2023

Tram Ho

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

<span class="token keyword">package</span> table

<span class="token keyword">import</span> <span class="token punctuation">(</span>
	<span class="token string">"errors"</span>
	<span class="token string">"fmt"</span>
<span class="token punctuation">)</span>

<span class="token keyword">func</span> <span class="token function">Divide</span><span class="token punctuation">(</span>x<span class="token punctuation">,</span> y <span class="token builtin">int8</span><span class="token punctuation">)</span> <span class="token punctuation">(</span><span class="token operator">*</span><span class="token builtin">string</span><span class="token punctuation">,</span> <span class="token builtin">error</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
	<span class="token keyword">if</span> y <span class="token operator">==</span> <span class="token number">0</span> <span class="token punctuation">{</span>
		<span class="token keyword">return</span> <span class="token boolean">nil</span><span class="token punctuation">,</span> errors<span class="token punctuation">.</span><span class="token function">New</span><span class="token punctuation">(</span><span class="token string">"cannot divide by 0"</span><span class="token punctuation">)</span>
	<span class="token punctuation">}</span>
	r <span class="token operator">:=</span> <span class="token function">float64</span><span class="token punctuation">(</span>x<span class="token punctuation">)</span> <span class="token operator">/</span> <span class="token function">float64</span><span class="token punctuation">(</span>y<span class="token punctuation">)</span>
	result <span class="token operator">:=</span> fmt<span class="token punctuation">.</span><span class="token function">Sprintf</span><span class="token punctuation">(</span><span class="token string">"%.2f"</span><span class="token punctuation">,</span> r<span class="token punctuation">)</span>
	<span class="token keyword">return</span> <span class="token operator">&amp;</span>result<span class="token punctuation">,</span> <span class="token boolean">nil</span>
<span class="token punctuation">}</span>

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

<span class="token keyword">package</span> table_test

<span class="token keyword">import</span> <span class="token punctuation">(</span>
	<span class="token string">"errors"</span>
	<span class="token string">"testing"</span>

	<span class="token string">"github.com/donhuvy/Test-Driven-Development-in-Go/chapter04/table"</span>
	<span class="token string">"github.com/stretchr/testify/assert"</span>
<span class="token punctuation">)</span>

<span class="token keyword">func</span> <span class="token function">TestDivide</span><span class="token punctuation">(</span>t <span class="token operator">*</span>testing<span class="token punctuation">.</span>T<span class="token punctuation">)</span> <span class="token punctuation">{</span>
	tests <span class="token operator">:=</span> <span class="token keyword">map</span><span class="token punctuation">[</span><span class="token builtin">string</span><span class="token punctuation">]</span><span class="token keyword">struct</span> <span class="token punctuation">{</span>
		x<span class="token punctuation">,</span> y    <span class="token builtin">int</span>
		wantErr <span class="token builtin">error</span>
		want    <span class="token builtin">string</span>
	<span class="token punctuation">}</span><span class="token punctuation">{</span>
		<span class="token string">"pos x, pos y"</span><span class="token punctuation">:</span>   <span class="token punctuation">{</span>x<span class="token punctuation">:</span> <span class="token number">8</span><span class="token punctuation">,</span> y<span class="token punctuation">:</span> <span class="token number">4</span><span class="token punctuation">,</span> want<span class="token punctuation">:</span> <span class="token string">"2.00"</span><span class="token punctuation">}</span><span class="token punctuation">,</span>
		<span class="token string">"neg x, neg y"</span><span class="token punctuation">:</span>   <span class="token punctuation">{</span>x<span class="token punctuation">:</span> <span class="token operator">-</span><span class="token number">4</span><span class="token punctuation">,</span> y<span class="token punctuation">:</span> <span class="token operator">-</span><span class="token number">8</span><span class="token punctuation">,</span> want<span class="token punctuation">:</span> <span class="token string">"0.50"</span><span class="token punctuation">}</span><span class="token punctuation">,</span>
		<span class="token string">"equal x, y"</span><span class="token punctuation">:</span>     <span class="token punctuation">{</span>x<span class="token punctuation">:</span> <span class="token number">4</span><span class="token punctuation">,</span> y<span class="token punctuation">:</span> <span class="token number">4</span><span class="token punctuation">,</span> want<span class="token punctuation">:</span> <span class="token string">"1.00"</span><span class="token punctuation">}</span><span class="token punctuation">,</span>
		<span class="token string">"max x, pos y"</span><span class="token punctuation">:</span>   <span class="token punctuation">{</span>x<span class="token punctuation">:</span> <span class="token number">127</span><span class="token punctuation">,</span> y<span class="token punctuation">:</span> <span class="token number">2</span><span class="token punctuation">,</span> want<span class="token punctuation">:</span> <span class="token string">"63.50"</span><span class="token punctuation">}</span><span class="token punctuation">,</span>
		<span class="token string">"min x, pos y"</span><span class="token punctuation">:</span>   <span class="token punctuation">{</span>x<span class="token punctuation">:</span> <span class="token operator">-</span><span class="token number">128</span><span class="token punctuation">,</span> y<span class="token punctuation">:</span> <span class="token number">2</span><span class="token punctuation">,</span> want<span class="token punctuation">:</span> <span class="token string">"-64.00"</span><span class="token punctuation">}</span><span class="token punctuation">,</span>
		<span class="token string">"zero x, pos y"</span><span class="token punctuation">:</span>  <span class="token punctuation">{</span>x<span class="token punctuation">:</span> <span class="token number">0</span><span class="token punctuation">,</span> y<span class="token punctuation">:</span> <span class="token number">2</span><span class="token punctuation">,</span> want<span class="token punctuation">:</span> <span class="token string">"0.00"</span><span class="token punctuation">}</span><span class="token punctuation">,</span>
		<span class="token string">"pos x, zero y"</span><span class="token punctuation">:</span>  <span class="token punctuation">{</span>x<span class="token punctuation">:</span> <span class="token number">10</span><span class="token punctuation">,</span> y<span class="token punctuation">:</span> <span class="token number">0</span><span class="token punctuation">,</span> wantErr<span class="token punctuation">:</span> errors<span class="token punctuation">.</span><span class="token function">New</span><span class="token punctuation">(</span><span class="token string">"cannot divide by 0"</span><span class="token punctuation">)</span><span class="token punctuation">}</span><span class="token punctuation">,</span>
		<span class="token string">"zero x, zero y"</span><span class="token punctuation">:</span> <span class="token punctuation">{</span>x<span class="token punctuation">:</span> <span class="token number">0</span><span class="token punctuation">,</span> y<span class="token punctuation">:</span> <span class="token number">0</span><span class="token punctuation">,</span> wantErr<span class="token punctuation">:</span> errors<span class="token punctuation">.</span><span class="token function">New</span><span class="token punctuation">(</span><span class="token string">"cannot divide by 0"</span><span class="token punctuation">)</span><span class="token punctuation">}</span><span class="token punctuation">,</span>
		<span class="token string">"max x, max y"</span><span class="token punctuation">:</span>   <span class="token punctuation">{</span>x<span class="token punctuation">:</span> <span class="token number">127</span><span class="token punctuation">,</span> y<span class="token punctuation">:</span> <span class="token number">127</span><span class="token punctuation">,</span> want<span class="token punctuation">:</span> <span class="token string">"1.00"</span><span class="token punctuation">}</span><span class="token punctuation">,</span>
		<span class="token string">"min x, min y"</span><span class="token punctuation">:</span>   <span class="token punctuation">{</span>x<span class="token punctuation">:</span> <span class="token operator">-</span><span class="token number">128</span><span class="token punctuation">,</span> y<span class="token punctuation">:</span> <span class="token operator">-</span><span class="token number">128</span><span class="token punctuation">,</span> want<span class="token punctuation">:</span> <span class="token string">"1.00"</span><span class="token punctuation">}</span><span class="token punctuation">,</span>
	<span class="token punctuation">}</span>

	<span class="token keyword">for</span> name<span class="token punctuation">,</span> rtc <span class="token operator">:=</span> <span class="token keyword">range</span> tests <span class="token punctuation">{</span>
		tc <span class="token operator">:=</span> rtc
		t<span class="token punctuation">.</span><span class="token function">Run</span><span class="token punctuation">(</span>name<span class="token punctuation">,</span> <span class="token keyword">func</span><span class="token punctuation">(</span>t <span class="token operator">*</span>testing<span class="token punctuation">.</span>T<span class="token punctuation">)</span> <span class="token punctuation">{</span>
			t<span class="token punctuation">.</span><span class="token function">Parallel</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
			x<span class="token punctuation">,</span> y <span class="token operator">:=</span> <span class="token function">int8</span><span class="token punctuation">(</span>tc<span class="token punctuation">.</span>x<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token function">int8</span><span class="token punctuation">(</span>tc<span class="token punctuation">.</span>y<span class="token punctuation">)</span>
			r<span class="token punctuation">,</span> err <span class="token operator">:=</span> table<span class="token punctuation">.</span><span class="token function">Divide</span><span class="token punctuation">(</span>x<span class="token punctuation">,</span> y<span class="token punctuation">)</span>
			<span class="token keyword">if</span> tc<span class="token punctuation">.</span>wantErr <span class="token operator">!=</span> <span class="token boolean">nil</span> <span class="token punctuation">{</span>
				assert<span class="token punctuation">.</span><span class="token function">Equal</span><span class="token punctuation">(</span>t<span class="token punctuation">,</span> tc<span class="token punctuation">.</span>wantErr<span class="token punctuation">,</span> err<span class="token punctuation">)</span>
				<span class="token keyword">return</span>
			<span class="token punctuation">}</span>
			assert<span class="token punctuation">.</span><span class="token function">Nil</span><span class="token punctuation">(</span>t<span class="token punctuation">,</span> err<span class="token punctuation">)</span>
			assert<span class="token punctuation">.</span><span class="token function">Equal</span><span class="token punctuation">(</span>t<span class="token punctuation">,</span> tc<span class="token punctuation">.</span>want<span class="token punctuation">,</span> <span class="token operator">*</span>r<span class="token punctuation">)</span>
		<span class="token punctuation">}</span><span class="token punctuation">)</span>
	<span class="token punctuation">}</span>
<span class="token punctuation">}</span>

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 <span class="token builtin class-name">test</span> -run TestDivide ./chapter04/table/ -v

1 2	firerose@firerose-desktop:~/Documents/github/Test-Driven-Development-in-Go$ go <span class="token builtin class-name">test</span> -run TestDivide ./chapter04/table/ -v

Result

    <span class="token operator">--</span><span class="token operator">-</span> PASS<span class="token punctuation">:</span> TestDivide<span class="token operator">/</span>max_x<span class="token punctuation">,</span>_pos_y <span class="token punctuation">(</span><span class="token number">0.00</span>s<span class="token punctuation">)</span>
    <span class="token operator">--</span><span class="token operator">-</span> PASS<span class="token punctuation">:</span> TestDivide<span class="token operator">/</span>pos_x<span class="token punctuation">,</span>_pos_y <span class="token punctuation">(</span><span class="token number">0.00</span>s<span class="token punctuation">)</span>
    <span class="token operator">--</span><span class="token operator">-</span> PASS<span class="token punctuation">:</span> TestDivide<span class="token operator">/</span>pos_x<span class="token punctuation">,</span>_zero_y <span class="token punctuation">(</span><span class="token number">0.00</span>s<span class="token punctuation">)</span>
    <span class="token operator">--</span><span class="token operator">-</span> PASS<span class="token punctuation">:</span> TestDivide<span class="token operator">/</span>zero_x<span class="token punctuation">,</span>_zero_y <span class="token punctuation">(</span><span class="token number">0.00</span>s<span class="token punctuation">)</span>
    <span class="token operator">--</span><span class="token operator">-</span> PASS<span class="token punctuation">:</span> TestDivide<span class="token operator">/</span>zero_x<span class="token punctuation">,</span>_pos_y <span class="token punctuation">(</span><span class="token number">0.00</span>s<span class="token punctuation">)</span>
    <span class="token operator">--</span><span class="token operator">-</span> PASS<span class="token punctuation">:</span> TestDivide<span class="token operator">/</span>max_x<span class="token punctuation">,</span>_max_y <span class="token punctuation">(</span><span class="token number">0.00</span>s<span class="token punctuation">)</span>
    <span class="token operator">--</span><span class="token operator">-</span> PASS<span class="token punctuation">:</span> TestDivide<span class="token operator">/</span>neg_x<span class="token punctuation">,</span>_neg_y <span class="token punctuation">(</span><span class="token number">0.00</span>s<span class="token punctuation">)</span>
    <span class="token operator">--</span><span class="token operator">-</span> PASS<span class="token punctuation">:</span> TestDivide<span class="token operator">/</span>equal_x<span class="token punctuation">,</span>_y <span class="token punctuation">(</span><span class="token number">0.00</span>s<span class="token punctuation">)</span>
PASS
ok      github<span class="token punctuation">.</span>com<span class="token operator">/</span>donhuvy<span class="token operator">/</span>Test<span class="token operator">-</span>Driven<span class="token operator">-</span>Development<span class="token operator">-</span>in<span class="token operator">-</span>Go<span class="token operator">/</span>chapter04<span class="token operator">/</span>table        <span class="token number">0.002</span>s

--- 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<span class="token punctuation">.</span><span class="token function">Equal</span><span class="token punctuation">(</span>t<span class="token punctuation">,</span> tc<span class="token punctuation">.</span>wantErr<span class="token punctuation">,</span> err<span class="token punctuation">)</span>

assert.Nil() receive 2 parameters likes this

assert<span class="token punctuation">.</span><span class="token function">Nil</span><span class="token punctuation">(</span>t<span class="token punctuation">,</span> err<span class="token punctuation">)</span>

1 2	assert<span class="token punctuation">.</span><span class="token function">Nil</span><span class="token punctuation">(</span>t<span class="token punctuation">,</span> err<span class="token punctuation">)</span>

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

<span class="token comment">// Code generated by mockery v2.26.1. DO NOT EDIT.</span>

1 2	<span class="token comment">// Code generated by mockery v2.26.1. DO NOT EDIT.</span>

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$ <span class="token builtin class-name">pwd</span>
/home/firerose/Downloads/go/bin
firerose@firerose-desktop:~/Downloads/go/bin$ <span class="token builtin class-name">export</span> <span class="token assign-left variable"><span class="token environment constant">PATH</span></span><span class="token operator">=</span>/home/firerose/Downloads/go/bin:<span class="token environment constant">$PATH</span>
firerose@firerose-desktop:~/Downloads/go/bin$ <span class="token builtin class-name">echo</span> <span class="token environment constant">$PATH</span>
/home/firerose/Downloads/go/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/snap/bin
firerose@firerose-desktop:~/Downloads/go/bin$ go version
go version go1.20.4 linux/amd64
firerose@firerose-desktop:~/Downloads/go/bin$

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

<span class="token keyword">go</span> install github<span class="token punctuation">.</span>com<span class="token operator">/</span>vektra<span class="token operator">/</span>mockery<span class="token operator">/</span>v2@v2<span class="token punctuation">.</span><span class="token number">26.1</span>

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

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Source : Viblo

Write unit test in Golang

Standard package for Go unit testing: package `testing`

Run unit testing with verbose information

Third-party library support Go lang unit testing

Third-party libraries support Go lang unit testing

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Standard package for Go unit testing: package testing

Run unit testing with verbose information

Third-party library support Go lang unit testing

Third-party libraries support Go lang unit testing

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Standard package for Go unit testing: package `testing`