How to Use Test Helpers in Go

Introduction
Prerequisites
Setting up the Test Helper
Writing Tests with Test Helpers
Conclusion

Introduction

In Go programming, test helpers are utility functions or methods that assist in writing tests. They provide reusable code snippets to simplify test setup, reduce duplication, and enhance test readability. In this tutorial, we will explore how to create and use test helpers in Go to improve the quality of our tests.

By the end of this tutorial, you will be able to:

Understand the importance of test helpers in Go testing
Create test helper functions or methods
Utilize test helpers to write cleaner and more efficient tests

Prerequisites

To follow along with this tutorial, you should have a basic understanding of Go programming and how to write tests using the standard testing package. Familiarity with functions and packages in Go is also beneficial. Make sure you have Go installed on your machine.

Setting up the Test Helper

To get started, let’s set up a project structure for writing tests with test helpers.

Create a new directory for your project and navigate into it:
```
 mkdir myproject
 cd myproject
```
Inside the project directory, create a directory named helpers to store our test helpers:
```
 mkdir helpers
```

Create a new Go module for our project:

 go mod init github.com/username/myproject

Open your favorite code editor and create a new file called helpers_test.go inside the helpers directory:
```
 touch helpers/helpers_test.go
```
We are now ready to create our first test helper function.

Writing Tests with Test Helpers

Let’s assume we are working on a project that involves various geometric calculations. We want to write tests for functions that calculate the area and perimeter of different shapes. In this example, we will focus on calculating the area of a rectangle.

Open the helpers_test.go file and define our test helper function:

 package helpers
    
 import (
     "testing"
 )
    
 func TestArea(t *testing.T, length, width float64, expected float64) {
     t.Helper()
    
     result := calculateArea(length, width)
     if result != expected {
         t.Errorf("Incorrect area. Got: %f, Expected: %f", result, expected)
     }
 }
    
 func calculateArea(length, width float64) float64 {
     return length * width
 }

In the above code, we define the TestArea function which takes a *testing.T and the parameters required for calculating the area of a rectangle. We mark this function as a helper using the t.Helper() line. This allows the Go test runner to skip this function during test discovery.

Now, let’s write a test case using our test helper:
```
 package helpers_test
    
 import (
     "testing"
    
     "github.com/username/myproject/helpers"
 )
    
 func TestRectangleArea(t *testing.T) {
     helpers.TestArea(t, 4.0, 5.0, 20.0)
 }
```
In the above code, we import our test helper function from the myproject/helpers package and use it within our test case function. We pass the testing instance t along with the required parameters to calculate the area of a rectangle.
To run the tests, execute the following command in the project root directory:
```
 go test ./...
```
If the test passes, you should see an output similar to:
```
 PASS
 ok      github.com/username/myproject/helpers 0.251s
```
Congratulations! You have successfully utilized a test helper to write a test.

Conclusion

In this tutorial, we learned how to use test helpers in Go to simplify the process of writing tests. We created a test helper function to calculate the area of a rectangle and demonstrated how to use it within a test case. Test helpers help in reducing code duplication, improving test readability, and providing reusable test setups.

Remember to organize your test helpers logically based on their purpose and reuse them across different test cases. Using test helpers can significantly enhance the maintainability and effectiveness of your tests.

Keep exploring different scenarios and functionalities in your own projects, and don’t hesitate to apply test helpers whenever they can simplify your testing process. Good luck with your Go testing journey!

Published: 16 January 2020