The conclusion is that you need to write tests, right?

Tests should be written for code that:

• Performs critical business logic where errors are critical.
• Is complex and contains many conditions where bugs can easily occur.
• Changes frequently to quickly identify regressions.
• Interacts with external systems to verify integration.

In Go, unit tests are usually written for functions and methods, as well as integration tests to check component interactions. An example of a simple test:

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

func TestAdd(t *testing.T) {
    result := Add(2, 3)
    if result != 5 {
        t.Errorf("Expected 5, got %d", result)
    }
}

Thus, tests are needed where they provide the maximum benefit — increasing reliability and simplifying code maintenance.