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// A sample program demonstrating using Google C++ testing framework.
//
// Author: wan@google.com (Zhanyong Wan)


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


// 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));
}

// 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?