C++：gtest samples1学习

samples1

sample1.cc

// Copyright 2005, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// A sample program demonstrating using Google C++ testing framework.

#include "sample1.h"

// Returns n! (the factorial of n).  For negative n, n! is defined to be 1.
int Factorial(int n) {
  int result = 1;
  for (int i = 1; i <= n; i++) {
    result *= i;
  }

  return result;
}

// Returns true if and only if n is a prime number.
bool IsPrime(int n) {
  // Trivial case 1: small numbers
  if (n <= 1) return false;

  // Trivial case 2: even numbers
  if (n % 2 == 0) return n == 2;

  // Now, we have that n is odd and n >= 3.

  // Try to divide n by every odd number i, starting from 3
  for (int i = 3;; i += 2) {
    // We only have to try i up to the square root of n
    if (i > n / i) break;

    // Now, we have i <= n/i < n.
    // If n is divisible by i, n is not prime.
    if (n % i == 0) return false;
  }

  // n has no integer factor in the range (1, n), and thus is prime.
  return true;
}

sample1.h

// Copyright 2005, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// A sample program demonstrating using Google C++ testing framework.

#ifndef GOOGLETEST_SAMPLES_SAMPLE1_H_
#define GOOGLETEST_SAMPLES_SAMPLE1_H_

// Returns n! (the factorial of n).  For negative n, n! is defined to be 1.
int Factorial(int n);

// Returns true if and only if n is a prime number.
bool IsPrime(int n);

#endif  // GOOGLETEST_SAMPLES_SAMPLE1_H_

sample1_unittest.cc

// Copyright 2005, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// A sample program demonstrating using Google C++ testing framework.

// This sample shows how to write a simple unit test for a function,
// using Google C++ testing framework.
//
// Writing a unit test using Google C++ testing framework is easy as 1-2-3:

// Step 1. Include necessary header files such that the stuff your
// test logic needs is declared.
//
// Don't forget gtest.h, which declares the testing framework.

#include "sample1.h"

#include <limits.h>

#include "gtest/gtest.h"
namespace {

// Step 2. Use the TEST macro to define your tests.
//
// TEST has two parameters: the test case name and the test name.
// After using the macro, you should define your test logic between a
// pair of braces.  You can use a bunch of macros to indicate the
// success or failure of a test.  EXPECT_TRUE and EXPECT_EQ are
// examples of such macros.  For a complete list, see gtest.h.
//
// <TechnicalDetails>
//
// In Google Test, tests are grouped into test cases.  This is how we
// keep test code organized.  You should put logically related tests
// into the same test case.
//
// The test case name and the test name should both be valid C++
// identifiers.  And you should not use underscore (_) in the names.
//
// Google Test guarantees that each test you define is run exactly
// once, but it makes no guarantee on the order the tests are
// executed.  Therefore, you should write your tests in such a way
// that their results don't depend on their order.
//
// </TechnicalDetails>

// Tests Factorial().

// Tests factorial of negative numbers.
TEST(FactorialTest, Negative) {
  // This test is named "Negative", and belongs to the "FactorialTest"
  // test case.
  EXPECT_EQ(1, Factorial(-5));
  EXPECT_EQ(1, Factorial(-1));
  EXPECT_GT(Factorial(-10), 0);

  // <TechnicalDetails>
  //
  // EXPECT_EQ(expected, actual) is the same as
  //
  //   EXPECT_TRUE((expected) == (actual))
  //
  // except that it will print both the expected value and the actual
  // value when the assertion fails.  This is very helpful for
  // debugging.  Therefore in this case EXPECT_EQ is preferred.
  //
  // On the other hand, EXPECT_TRUE accepts any Boolean expression,
  // and is thus more general.
  //
  // </TechnicalDetails>
}

// Tests factorial of 0.
TEST(FactorialTest, Zero) { EXPECT_EQ(1, Factorial(0)); }

// Tests factorial of positive numbers.
TEST(FactorialTest, Positive) {
  EXPECT_EQ(1, Factorial(1));
  EXPECT_EQ(2, Factorial(2));
  EXPECT_EQ(6, Factorial(3));
  EXPECT_EQ(40320, Factorial(8));
}

// Tests IsPrime()

// Tests negative input.
TEST(IsPrimeTest, Negative) {
  // This test belongs to the IsPrimeTest test case.

  EXPECT_FALSE(IsPrime(-1));
  EXPECT_FALSE(IsPrime(-2));
  EXPECT_FALSE(IsPrime(INT_MIN));
}

// Tests some trivial cases.
TEST(IsPrimeTest, Trivial) {
  EXPECT_FALSE(IsPrime(0));
  EXPECT_FALSE(IsPrime(1));
  EXPECT_TRUE(IsPrime(2));
  EXPECT_TRUE(IsPrime(3));
}

// Tests positive input.
TEST(IsPrimeTest, Positive) {
  EXPECT_FALSE(IsPrime(4));
  EXPECT_TRUE(IsPrime(5));
  EXPECT_FALSE(IsPrime(6));
  EXPECT_TRUE(IsPrime(23));
}
}  // namespace

// Step 3. Call RUN_ALL_TESTS() in main().
//
// We do this by linking in src/gtest_main.cc file, which consists of
// a main() function which calls RUN_ALL_TESTS() for us.
//
// This runs all the tests you've defined, prints the result, and
// returns 0 if successful, or 1 otherwise.
//
// Did you notice that we didn't register the tests?  The
// RUN_ALL_TESTS() macro magically knows about all the tests we
// defined.  Isn't this convenient?

EXPECT_FALSE

用于验证给定的布尔表达式是否为 false。如果表达式的值为 false，则测试通过；如果为 true，则测试失败，并输出相应的错误信息，但测试会继续执行后续的断言。

#include <gtest/gtest.h>

TEST(ExampleTest, FalseCondition) {
    bool value = false;
    EXPECT_FALSE(value);
}

int main(int argc, char **argv) {
    ::testing::InitGoogleTest(&argc, argv);
    return RUN_ALL_TESTS();
}

EXPECT_TRUE

用于验证给定的布尔表达式是否为 true。如果表达式的值为 true，则测试通过；如果为 false，则测试失败，并输出相应的错误信息，但测试会继续执行后续的断言。

#include <gtest/gtest.h>

TEST(ExampleTest, TrueCondition) {
    bool value = true;
    EXPECT_TRUE(value);
}

int main(int argc, char **argv) {
    ::testing::InitGoogleTest(&argc, argv);
    return RUN_ALL_TESTS();
}

EXPECT_EQ

用于验证两个值是否相等。这里的值可以是基本数据类型（如整数、浮点数等），也可以是自定义类型（前提是该类型重载了 == 运算符）。如果两个值相等，则测试通过；如果不相等，则测试失败，并输出相应的错误信息，但测试会继续执行后续的断言。

#include <gtest/gtest.h>

TEST(ExampleTest, EqualValues) {
    int expected = 5;
    int actual = 5;
    EXPECT_EQ(expected, actual);
}

int main(int argc, char **argv) {
    ::testing::InitGoogleTest(&argc, argv);
    return RUN_ALL_TESTS();
}

EXPECT_GT

用于验证第一个值是否大于第二个值。如果第一个值大于第二个值，则测试通过；如果不满足该条件，则测试失败，并输出相应的错误信息，但测试会继续执行后续的断言。

#include <gtest/gtest.h>

TEST(ExampleTest, GreaterThan) {
    int val1 = 10;
    int val2 = 5;
    EXPECT_GT(val1, val2);
}

int main(int argc, char **argv) {
    ::testing::InitGoogleTest(&argc, argv);
    return RUN_ALL_TESTS();
}

除了 EXPECT_* 系列的断言宏，gtest 还有 ASSERT_* 系列的断言宏，如 ASSERT_FALSE、ASSERT_TRUE、ASSERT_EQ 和 ASSERT_GT 等。它们的功能与 EXPECT_* 系列类似，但当 ASSERT_* 断言失败时，当前测试函数会立即终止执行。
在使用浮点数进行比较时，由于浮点数的精度问题，不建议直接使用 EXPECT_EQ 进行比较，而是使用 EXPECT_NEAR 等专门的断言宏。