Table-Driven Tests in Go

Table-driven tests are a powerful and efficient technique for writing unit tests in Go. They allow developers to create comprehensive test suites with minimal code duplication.

What are Table-Driven Tests?

Table-driven tests involve defining a slice of test cases, each containing input data and expected output. The test function then iterates through these cases, running the same test logic for each one.

Benefits of Table-Driven Tests

• Improved code readability
• Easy addition of new test cases
• Reduced code duplication
• Better test coverage

Basic Structure

A typical table-driven test in Go consists of three main components:

1. A slice of test cases
2. A loop that iterates through the test cases
3. The actual test logic

Example: Testing a Simple Function

Let's look at an example of a table-driven test for a function that adds two integers:

package main

import "testing"

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

func TestAdd(t *testing.T) {
    tests := []struct {
        name     string
        a, b     int
        expected int
    }{
        {"positive numbers", 2, 3, 5},
        {"negative numbers", -2, -3, -5},
        {"mixed numbers", -2, 3, 1},
    }

    for _, tt := range tests {
        t.Run(tt.name, func(t *testing.T) {
            result := Add(tt.a, tt.b)
            if result != tt.expected {
                t.Errorf("Add(%d, %d) = %d; want %d", tt.a, tt.b, result, tt.expected)
            }
        })
    }
}
    

In this example, we define a slice of test cases, each with a name, input values, and expected output. The test function then iterates through these cases, running the Add function and comparing the result to the expected value.

Best Practices

• Use descriptive names for test cases
• Include edge cases and boundary conditions
• Keep test cases simple and focused
• Use t.Run() for subtests to improve output readability

Advanced Techniques

Table-driven tests can be extended to handle more complex scenarios:

• Testing functions with multiple return values
• Using helper functions to generate test cases
• Combining table-driven tests with Go Benchmark Testing

Integration with Go Testing Package

Table-driven tests integrate seamlessly with Go's built-in testing package. They can be used alongside other testing techniques to create comprehensive test suites.

Conclusion

Table-driven tests are an essential tool in Go programming. They enhance test maintainability, readability, and coverage. By mastering this technique, developers can create more robust and efficient test suites for their Go projects.

To further improve your Go testing skills, explore related concepts such as Go Unit Testing and Go Test Coverage.