How to unit test C++ function library?

Using Google Test for unit testing in a C function library can ensure its reliability. The specific steps are as follows: Install Google Test to create a unit test for the function library: Create a ".test.cpp" file and include the Google Test header definition inherited from ::testing::Test's test case class creates a test method starting with TEST. Run the unit test: use the gtest executable file and pass in the test case file. Use other assertion macros: ASSERT_EQ (abort the test), ASSERT_TRUE/ASSERT_FALSE (check the condition) , ASSERT_THROW (check exception thrown)

How to perform unit testing in C function library

Introduction
Unit testing is crucial to ensuring that the function library is reliable. One of the commonly used unit testing frameworks in C is Google Test, which provides a series of macros and functions that simplify the testing process. This article will guide you on how to use Google Test for unit testing in a C library.

Install Google Test
You can install Google Test from source using the following command:

git clone https://github.com/google/googletest
cd googletest
mkdir build
cd build
cmake .. -Dgtest_build_samples=ON
make

Set up unit testing
To be To write a unit test for a function library, please follow the steps below:

1. Create a new file containing test cases, usually ending with ".test.cpp".
2. Call #include<gtest/gtest.h> Contains the Google Test headers.
3. Define a test case class, which inherits from the ::testing::Test base class.
4. Create a test method in the test case class, with the method name starting with TEST.

Practical case: Testing a simple function
Consider a function named factorial that calculates the factorial of a given non-negative integer . Let's write a unit test to test this function:

#include "factorial.h"
#include "gtest/gtest.h"

TEST(FactorialTest, BasicTest) {
  EXPECT_EQ(1, factorial(0));
  EXPECT_EQ(1, factorial(1));
  EXPECT_EQ(2, factorial(2));
  EXPECT_EQ(6, factorial(3));
  EXPECT_EQ(24, factorial(4));
}

In this test case:

• TEST(FactorialTest, BasicTest) defines a function named BasicTest test method.
• EXPECT_EQ Macro is used to compare expected results with actual results.

Running Unit Tests
To run unit tests, use the gtest executable. Pass in the test case file as parameter:

./gtest tests.test.cpp

The output will show the passed and failed test cases.

Other assertion macros
Google Test provides other assertion macros, such as:

• ASSERT_EQ: and EXPECT_EQ Similar, but abort the test on failure.
• ASSERT_TRUE and ASSERT_FALSE: Check whether the condition is true or false respectively.
• ASSERT_THROW: Check whether the calling function throws the specified exception.

Conclusion
Unit testing in a C library is very easy using Google Test. By following the steps outlined in this article, you can write robust and reliable unit tests that ensure your library works as expected.

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