Coverage-driven unit testing of Go functions

Go function unit testing can ensure complete code coverage through a coverage-driven approach. The approach consists of writing test cases to cover different use cases of the function. Run tests with the -cover flag to generate coverage reports. Check the report to determine if all lines of code are covered, if not add more test cases.

Coverage-driven Go function unit testing

Introduction

Unit testing It is a crucial step in software development and helps ensure the correctness of the code. Go provides a powerful testing package that supports writing unit tests for functions. With coverage-driven testing, we ensure complete code coverage.

Coverage Summary

Coverage measures the percentage of lines of code that are executed during test execution. Higher coverage indicates more comprehensive testing.

Coverage in Go

Go provides the cover tool to calculate test coverage. To use it, before running the test command, you need to add the -cover flag:

go test -cover

This will output a coverage report listing the lines of code that are not covered and the coverage percentage.

Practical case

Let us consider the following sum function:

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

To write a coverage-driven unit for this function To test, please perform the following steps:

1. Write a test case: Write a test function to test different use cases of the sum function.
2. Using coverage: Run tests using the cover flag. This will generate a coverage report.
3. Compare coverage: Check the coverage report to determine whether all lines of code are covered. If it's not covered, add more test cases to cover the code that's not covered.

Step-by-Step Example

The following is a step-by-step example:

Step One: Write Test Cases

package main

import (
    "testing"
)

func TestSum(t *testing.T) {
    // 测试用例 1
    result := sum(1, 2)
    expected := 3
    if result != expected {
        t.Errorf("Test case 1 failed: expected %d, got %d", expected, result)
    }
    
    // 测试用例 2
    result = sum(0, 0)
    expected = 0
    if result != expected {
        t.Errorf("Test case 2 failed: expected %d, got %d", expected, result)
    }
}

Step 2: Use coverage

go test -cover

Step 3: Compare coverage

Rungo test -cover will output a coverage report:

coverage: 100.0% of statements in main.go

This means that all lines of code in the sum function have been covered.

Conclusion

Coverage-driven unit testing is an effective way to ensure the correctness of Go functions. By using the cover tool we can easily calculate coverage and add more test cases for the uncovered lines of code.

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