When is it appropriate to use C++ function unit testing?

Functional unit testing is an automated testing technique used to test the expected behavior of a C function in isolation. Applicable to the following scenarios: Verify function behavior Check boundary conditions Detect errors Refactor code as documentation

When to use C function unit testing

Function unit testing is an automated testing technology that performs isolated testing of C functions. It helps you ensure that functions work as expected and detect edge cases or errors.

Here are some situations when it is appropriate to use function unit testing:

• Verify the behavior of the function: Test whether the function returns the expected value according to the specification.
• Check boundary conditions: Test the behavior of a function outside the input or output range.
• Detecting errors: Identify problems that cause functions to behave unexpectedly.
• When refactoring code: Make sure that code changes do not accidentally affect the behavior of the function.
• As documentation: Unit tests can serve as detailed descriptions of the expected behavior of a function.

Practical Case

Let us consider a simple C function that calculates the sum of two numbers:

int add(int a, int b) {
  return a + b;
}

We can use Google Test framework writes a unit test to verify the behavior of this function:

#include <gtest/gtest.h>

TEST(AddFunctionTest, PositiveNumbers) {
  EXPECT_EQ(add(1, 2), 3);
  EXPECT_EQ(add(4, 5), 9);
}

TEST(AddFunctionTest, NegativeNumbers) {
  EXPECT_EQ(add(-1, -2), -3);
  EXPECT_EQ(add(-3, -4), -7);
}

Code description:

• TEST() Macro definition A unit test.
• EXPECT_EQ() Asserts that two expressions have equal values.
• We can write multiple test cases for each different test case.

Running these tests will verify the expected behavior of the add() function under different inputs.

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