int Factorial(int n) {
  int result = 1;
  for (int i = 1; i <= n; i++) {
    result *= i;
  }

  return result;
}

// Returns true iff 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 squre 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;
}

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));
}

Running main() from gtest_main.cc
[==========] Running 6 tests from 2 test cases.
[----------] Global test environment set-up.
[----------] 3 tests from FactorialTest
[ RUN      ] FactorialTest.Negative
[       OK ] FactorialTest.Negative (0 ms)
[ RUN      ] FactorialTest.Zero
[       OK ] FactorialTest.Zero (0 ms)
[ RUN      ] FactorialTest.Positive
[       OK ] FactorialTest.Positive (0 ms)
[----------] 3 tests from FactorialTest (0 ms total)

[----------] 3 tests from IsPrimeTest
[ RUN      ] IsPrimeTest.Negative
[       OK ] IsPrimeTest.Negative (0 ms)
[ RUN      ] IsPrimeTest.Trivial
[       OK ] IsPrimeTest.Trivial (0 ms)
[ RUN      ] IsPrimeTest.Positive
[       OK ] IsPrimeTest.Positive (0 ms)
[----------] 3 tests from IsPrimeTest (0 ms total)

[----------] Global test environment tear-down
[==========] 6 tests from 2 test cases ran. (0 ms total)
[  PASSED  ] 6 tests.

//sample.h
class MyOffset{
 public:
  MyOffset() {}
  virtual ~MyOffset() {}

  /*
   * Set the offsest
   */
  int SetOffset(int offset);

  /*
   * Returns the current offset
   */
  int offset() const { return offset_; }

 protected:
  /*
   * Set the offset
   *
   * This method is called by the public SetOffset() method.
   */
  virtual int DoSetOffset(int offset) = 0;

 private:
  int offset_; 
};

//sample.c
int MyOffset::SetOffset(int offset) {
  if (offset < 0) {
    offset_ = -1;
    return -1;
  }
  offset_ = DoSetOffset(offset);
  return offset_;
}

#include <gmock/gmock.h>
#include <gtest/gtest.h>

class MockMyOffset : public MyOffset {
 public:
  MockMyOffset() {}
  virtual ~MockMyOffset() {}

  MOCK_METHOD1(DoSetOffset, int(int offset));
};

TEST(MyOffsetTest, SetOffset) {
  MockMyOffset my_offset;
  /* 当DoSetOffset的进入参数是10,就返回一次10 */
  EXPECT_CALL(my_offset, DoSetOffset(10)).WillOnce(Return(10));
  EXPECT_EQ(10, my_offset.SetOffset(10));
  EXPECT_EQ(10, my_offset.offset());

  EXPECT_CALL(my_offset, DoSetOffset(5)).WillOnce(Return(5));
  EXPECT_EQ(5, my_offset.SetOffset(5));
  EXPECT_EQ(5, my_offset.offset());

  EXPECT_CALL(my_offset, DoSetOffset(20)).WillOnce(Return(1));
  EXPECT_EQ(1, my_offset.SetOffset(20));
  EXPECT_EQ(1, my_offset.offset());

  EXPECT_CALL(my_offset, DoSetOffset(10)).WillOnce(Return(-1));
  EXPECT_EQ(-1, my_offset.SetOffset(10));
  EXPECT_EQ(-1, my_offset.offset());
}

➜  bin  ./sample_test 
Running main() from gtest_main.cc
[==========] Running 1 test from 1 test case.
[----------] Global test environment set-up.
[----------] 1 test from MyOffsetTest
[ RUN      ] MyOffsetTest.SetOffset
[       OK ] MyOffsetTest.SetOffset (0 ms)
[----------] 1 test from MyOffsetTest (0 ms total)

[----------] Global test environment tear-down
[==========] 1 test from 1 test case ran. (0 ms total)
[  PASSED  ] 1 test.