Analysis of black box testing and white box testing technology of PHP code testing function

#Analysis of black box testing and white box testing technology of PHP code testing function

Introduction:
Testing is very important when developing and maintaining PHP applications of a link. Through testing, we can verify the correctness, stability, and security of the code, thereby improving the quality of the application. This article will focus on the PHP code testing function, focusing on two commonly used testing techniques, black box testing and white box testing, and will provide some code examples to deepen understanding.

1. Black box testing
Black box testing is a functional testing method. It treats the program under test as a black box and only cares about input and output without caring about the internal implementation details of the program. Three commonly used techniques for black box testing include equivalence class division, boundary value analysis and error speculation.

1. Equivalence class division
   Equivalence class division is a method of designing test cases. It divides all possible values ​​of the input value into several equivalence classes, and then separates them from each equivalence class. Select a test case from the price category for testing. In PHP code testing, equivalence class division can effectively reduce the number of test cases and cover all possible input values.

Example 1:

/**
 * 判断输入年份是否为闰年（能被4整除但不能被100整除，或者能被400整除）
 *
 * @param int $year
 * @return bool
 */
function isLeapYear($year)
{
    if (($year % 4 == 0 && $year % 100 != 0) || $year % 400 == 0) {
        return true;
    } else {
        return false;
    }
}

// 测试用例
assert(isLeapYear(2000) === true);  // 基本等价类：2000为能被400整除的年份，属于闰年
assert(isLeapYear(1900) === false);  // 基本等价类：1900为能被100整除但不能被400整除的年份，不属于闰年
assert(isLeapYear(2020) === true);  // 附加等价类：2020为能被4整除但不能被100整除的年份，属于闰年
assert(isLeapYear(2021) === false);  // 附加等价类：2021为既不能被4整除也不能被100整除的年份，不属于闰年

2. Boundary value analysis
   Boundary value analysis is a method of test case design that focuses on the boundary conditions of input and output. Test cases usually select minimum and maximum boundary values ​​for testing, as well as situations near boundary values. In PHP code testing, boundary value analysis can effectively discover input or output anomalies.

Example 2:

/**
 * 判断输入的数值是否在范围内
 *
 * @param int $number
 * @return bool
 */
function isInRange($number)
{
    if ($number >= 10 && $number <= 100) {
        return true;
    } else {
        return false;
    }
}

// 测试用例
assert(isInRange(5) === false);  // 边界情况：最小边界值，不在范围内
assert(isInRange(10) === true);  // 边界情况：最小边界值，正好在范围内
assert(isInRange(50) === true);  // 正常情况：在范围内
assert(isInRange(100) === true);  // 边界情况：最大边界值，正好在范围内
assert(isInRange(200) === false);  // 边界情况：最大边界值，不在范围内

3. Error speculation
   Error speculation is a testing method based on experience and intuition. It designs by guessing possible error situations. Corresponding test cases. In PHP code testing, error speculation can help us find potential errors and anomalies.

Example 3:

/**
 * 判断输入的字符串是否为有效的邮箱地址
 *
 * @param string $email
 * @return bool
 */
function isValidEmail($email)
{
    if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
        return true;
    } else {
        return false;
    }
}

// 测试用例
assert(isValidEmail('abc@domain.com') === true);  // 正常情况：有效的邮箱地址
assert(isValidEmail('abc@domain.') === false);  // 异常情况：无效的邮箱地址，缺少顶级域名
assert(isValidEmail('abc@@domain.com') === false);  // 异常情况：无效的邮箱地址，多个@符号
assert(isValidEmail('abc@domain') === false);  // 异常情况：无效的邮箱地址，缺少顶级域名

2. White-box testing
White-box testing is a structural testing method that focuses on the implementation details inside the program. By understanding the program structure and logic, design appropriate test cases to verify the execution of each branch and path. There are three commonly used techniques for white box testing: statement coverage, decision coverage and condition coverage.

1. Statement coverage
   Statement coverage is a testing technique commonly used in white-box testing, which ensures that each statement is executed at least once. Statement coverage can help us find potential logic errors and code errors.

Example 4:

/**
 * 计算两个数的和
 *
 * @param int $a
 * @param int $b
 * @return int
 */
function sum($a, $b)
{
    if ($a > $b) {
        return $a + $b;
    } else {
        return $b;
    }
}

// 测试用例
assert(sum(3, 5) === 8);  // 正常情况：$a > $b
assert(sum(5, 3) === 8);  // 正常情况：$a < $b
assert(sum(5, 5) === 5);  // 边界情况：$a = $b

2. Decision coverage
   Decision coverage is a more detailed testing technique in white box testing, which ensures that each decision condition Takes two possible values ​​(true and false). Decision coverage can help us find logical errors in judgment statements.

Example 5:

/**
 * 判断输入的数值是否为正数
 *
 * @param int $number
 * @return bool
 */
function isPositive($number)
{
    if ($number > 0) {
        return true;
    } else {
        return false;
    }
}

// 测试用例
assert(isPositive(5) === true);  // 正常情况：正数
assert(isPositive(0) === false);  // 边界情况：零不是正数
assert(isPositive(-5) === false);  // 正常情况：负数不是正数

3. Conditional coverage
   Conditional coverage is a more detailed testing technology in white box testing. It ensures that each logical condition is taken. Two possible values. Conditional coverage can help us find logical errors and conditional differences.

Example 6:

/**
 * 判断输入的两个数值是否相等
 *
 * @param int $a
 * @param int $b
 * @return bool
 */
function isEqual($a, $b)
{
    if ($a == $b || $a - $b < 1e-6) {
        return true;
    } else {
        return false;
    }
}

// 测试用例
assert(isEqual(5, 5) === true);  // 正常情况：两个数值相等
assert(isEqual(5, 4.999999) === true);  // 正常情况：两个数值相差很小
assert(isEqual(5, 4) === false);  // 正常情况：两个数值不相等

Conclusion:
Through the introduction of this article, we have learned about the black box testing and white box testing techniques commonly used in PHP code testing. Black box testing focuses on input and output, and designs test cases through equivalence class division, boundary value analysis, and error speculation. White-box testing focuses on the internal structure and designs test cases through statement coverage, decision coverage and condition coverage. By employing appropriate testing techniques, we are able to test PHP code more comprehensively and improve the quality and stability of our applications.

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