I’m a big fan of testing; it is a critical part of software engineering and how reliable software gets built. I am also a big fan of making tests easier to manage and maintain. The easier a set of tests are to maintain, the more they are maintained, making them more effective.

In today’s article, I will discuss a technique popular within the Go community for simplifying repetitive tests. This technique is called Table Tests, and I will show how to use Table Tests to reduce the number of test functions while simultaneously increasing code coverage.

What are Table Tests?

Table Tests are a great way to test functions with varying inputs and results. The idea behind Table Tests is rather than writing a unique test function for each combination of input and output, a single test function can iterate over a table of function inputs and validate expected results.

Basic Greeter

To best explain the concept of Table Tests, we will first create a simple set of functions that output various greetings in different languages.

We will then use Table Tests to iterate through the multiple languages and expected greetings.

// Config is used to configure a Greeter based on desired language parameters.
type Config struct {
 // Language is the language to use while greeting.
 Language string
}

// Greeting returns a greeting in the language specified by the Config.
type Greeter struct {
 language string
}

// New returns a new Greeter based on the provided Config.
func New(cfg Config) (*Greeter, error) {
 switch cfg.Language {
 case "en", "fr", "es", "de", "jp", "cn":
  return &Greeter{language: cfg.Language}, nil
 default:
  return nil, fmt.Errorf("unsupported language: %s", cfg.Language)
 }
}

// Greeting returns a greeting in the language specified by the Greeter.
func (g *Greeter) Greeting() string {
 switch g.language {
 case "en":
  return "Hello"
 case "fr":
  return "Bonjour"
 case "es":
  return "Hola"
 case "de":
  return "Hallo"
 case "jp":
  return "こんにちは"
 case "cn":
  return "你好"
 }
 return ""
}

We must first look at the New() function to understand the example code. This function takes in a Config struct that allows users to specify a…