Exercise 5: Writing Unit Tests in Go

Why Write Unit Tests?

Unit tests ensure that each part of your code works correctly and prevents regressions during updates.

Writing a Test Using the `testing` Package

Go includes the built-in `testing` package for writing and executing unit tests.

package main

import (
    "testing"
)

func Addition(a, b int) int {
    return a + b
}

func TestAddition(t *testing.T) {
    result := Addition(2, 3)
    expected := 5
    if result != expected {
        t.Errorf("Incorrect result: got %d, expected %d", result, expected)
    }
}

Running Tests

Tests can be executed with the command:

go test

Exercise Instructions

• Create a file named maths.go containing a function `Multiplication`.
• Create a file named maths_test.go to test this function.
• Write unit tests to validate the function's correctness.
• Run your tests using `go test`.

Exercise Solution

package main

import (
    "testing"
)

func Multiplication(a, b int) int {
    return a * b
}

func TestMultiplication(t *testing.T) {
    result := Multiplication(4, 5)
    expected := 20
    if result != expected {
        t.Errorf("Error: got %d, expected %d", result, expected)
    }
}

Best Practices & Common Errors

• ✅ Always test edge cases and expected errors.
• ✅ Use `t.Run` to organize tests into sub-tests.
• ✅ Automate test execution in a CI/CD pipeline.
• ⚠️ Never ignore errors or unexpected results.