?? Using Table-Driven Tests for Unit Testing in Go ??

Unit testing is an essential part of software development, helping ensure that your code behaves as expected. In Go, one of the most effective and maintainable ways to write tests is through table-driven tests. This method organizes test cases into a table (slice of structs) and iterates through them, running each case with the corresponding input and expected output. ???

Let’s dive into how table-driven tests can simplify your testing process and keep your Go code clean and readable.

Writing Tests ??

1. Create a Test File: place your test functions in a file with the _test.go suffix. For example, if you’re testing main.go, your test file should be named main_test.go.
2. Write a Test Function: Each test function must start with Test followed by the name of the function you’re testing, like this: func TestFunctionName(t *testing.T) { // Test logic here }
3. Use Assertions: Inside your test function, compare the result of the function being tested with the expected result. If they don’t match, call t.Errorf() or t.Fail() to indicate a test failure

Running Tests ??

Once you’ve written your test functions, you can run them with the command go test. This command will automatically find all the _test.go files in your package, run the test functions, and report the results.

Run all tests: "go test ./..." to run tests in the entire module.

Verbose output: Add -v to get more details: "go test -v".

What Are Table-Driven Tests? ??

Table-driven tests are a style of unit testing where:

1. You define a series of test cases in a table (slice of structs).
2. Each test case has input data and the expected result.
3. The tests iterate over the table and run for each case.

This approach eliminates redundant code by avoiding repeated test functions, making it easier to add, update, and maintain tests in the long run. ??

Writing a Simple Table-Driven Test

Let’s start with a simple example: testing a function that adds two numbers. Here is content of the add.go file and the test_add.go

Breakdown:

• We define a testCases slice that holds all the test scenarios, including the inputs (a and b) and the expected output.
• Inside the loop, t.Run() runs each test case with a descriptive name.
• The t.Errorf() function reports any failures when the result does not match the expected value.

Why Use Table-Driven Tests? ??

• Scalability: Adding new test cases is as simple as adding a new struct entry to the table.
• Readability: Test cases are neatly organized, and their intention is clear.
• Maintainability: Repeated test logic is avoided, making updates more straightforward.
• Flexibility: You can extend this approach to test more complex scenarios or edge cases.

Table-Driven Tests with Complex Types ??

Let’s take this concept a step further and apply it to a more complex example: testing a function that sorts a slice of integers.

Key Differences:

• Complex Inputs: The test cases involve slices instead of simple integers.
• reflect.DeepEqual: Since slices are reference types, we use reflect.DeepEqual() to compare the expected and actual output.

The test output

Running go test -v ./... resulted on the following output

?? Key Takeaways

• Table-driven tests keep your code clean and maintainable by avoiding repetition.
• They make it easy to extend and scale your tests with additional cases or more complex inputs.

Table-driven tests are a powerful tool in any Go developer’s testing toolkit, making your tests not only more structured but also more enjoyable to write!