Common pitfalls in C++ function unit testing?

Common pitfalls in C function unit testing include: Reliance on external state: Avoid using global or static variables to ensure test independence. Don't mock dependencies: Use stubs or mocks to mock external objects to prevent unexpected behavior or test failures. Tests are too broad: only assert the behavior of the function under test, avoid complex assertions and additional logic. Ignore boundary conditions: Include test cases for boundary values ​​to check the effectiveness of boundary checks. Do not handle exceptions: Explicitly check for exceptions that a function may throw to avoid global exception handling from masking test failures.

Common Pitfalls of C Function Unit Tests

Function unit tests are designed to test the functionality of a function in isolation, but when writing these tests When doing this, there are several common pitfalls to avoid.

Dependence on external state

Tests should be independent of external state. Avoid using global or static variables in tests as this affects other tests and the correctness of the application.

Do not mock dependencies

For functions that depend on external objects, they should be mocked with stubs or mocks. Calling dependencies directly may cause unexpected behavior or test failures.

Too broad

Tests should only assert the behavior of the tested function. Avoid using complex assertions that contain additional function calls or complex logic, as this increases the maintainability and readability of your tests.

Do not check boundary conditions

It is important that test cases that include boundaries include input or return values ​​that may cause boundary checks to fail or cause undefined behavior.

Do not handle exceptions

If a function may throw exceptions, the test should explicitly check for the occurrence of these exceptions. Avoid global handling of exceptions as this can mask test failures.

Practical case:

The following is an example of testing the sum function, which calculates the sum of two numbers:

#include <gtest/gtest.h>

TEST(SumFunction, PositiveIntegers) {
  ASSERT_EQ(5, sum(2, 3));
}

TEST(SumFunction, NegativeIntegers) {
  ASSERT_EQ(-1, sum(-2, -1));
}

TEST(SumFunction, BoundaryConditions) {
  ASSERT_EQ(INT_MAX, sum(INT_MAX, 0));
  ASSERT_EQ(INT_MIN, sum(INT_MIN, 0));
}

In this example we avoid common pitfalls:

• Testing independently of external state
• Use assertions to check exact function behavior
• At boundaries Test under conditions
• Check exception

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