// 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 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;
}

extern int Factorial(int n);
extern bool IsPrime(int n);
// 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(2, Factorial(-1)); //如果是ASSERT_EQ，后边的EXPECT_GT将不在执行；如果是EXPECT_EQ，后边的测试EXPECT_GT继续执行
	EXPECT_GT(Factorial(-10), 0);
	ASSERT_EQ(3, Factorial(-1));

	// <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));
}

// 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?

#include <limits.h>
#include "sample1.h"
#include <gtest/gtest.h>  

TEST(FactorialTest, Negative) {
  // This test is named "Negative", and belongs to the "FactorialTest"
  // test case.
  EXPECT_EQ(1, Factorial(-5));
  EXPECT_EQ(2, Factorial(-1)); //如果是ASSERT_EQ，后边的EXPECT_GT将不在执行；如果是EXPECT_EQ，后边的测试EXPECT_GT继续执行
  EXPECT_GT(Factorial(-10), 0);
  EXPECT_TRUE(2 == Factorial(-7));//这个错误失败信息打印的是true或false，不会打印值
  ASSERT_EQ(3, Factorial(-1));
} 

int main(int argc, char **argv) {
//printf("Running main() from gtest_main.cc\n");
testing::InitGoogleTest(&argc,argv);
return RUN_ALL_TESTS();
}