googletest/samples/sample2_unittest.cc

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

// This sample shows how to write a more complex unit test for a class
// that has multiple member functions.
//
// Usually, it's a good idea to have one test for each method in your
// class.  You don't have to do that exactly, but it helps to keep
// your tests organized.  You may also throw in additional tests as
// needed.

#include "sample2.h"
#include "gtest/gtest.h"
namespace {
// In this example, we test the MyString class (a simple string).

// Tests the default c'tor.
TEST(MyString, DefaultConstructor) {
  const MyString s;

  // Asserts that s.c_string() returns NULL.
  //
  // <TechnicalDetails>
  //
  // If we write NULL instead of
  //
  //   static_cast<const char *>(NULL)
  //
  // in this assertion, it will generate a warning on gcc 3.4.  The
  // reason is that EXPECT_EQ needs to know the types of its
  // arguments in order to print them when it fails.  Since NULL is
  // #defined as 0, the compiler will use the formatter function for
  // int to print it.  However, gcc thinks that NULL should be used as
  // a pointer, not an int, and therefore complains.
  //
  // The root of the problem is C++'s lack of distinction between the
  // integer number 0 and the null pointer constant.  Unfortunately,
  // we have to live with this fact.
  //
  // </TechnicalDetails>
  EXPECT_STREQ(nullptr, s.c_string());

  EXPECT_EQ(0u, s.Length());
}

const char kHelloString[] = "Hello, world!";

// Tests the c'tor that accepts a C string.
TEST(MyString, ConstructorFromCString) {
  const MyString s(kHelloString);
  EXPECT_EQ(0, strcmp(s.c_string(), kHelloString));
  EXPECT_EQ(sizeof(kHelloString)/sizeof(kHelloString[0]) - 1,
            s.Length());
}

// Tests the copy c'tor.
TEST(MyString, CopyConstructor) {
  const MyString s1(kHelloString);
  const MyString s2 = s1;
  EXPECT_EQ(0, strcmp(s2.c_string(), kHelloString));
}

// Tests the Set method.
TEST(MyString, Set) {
  MyString s;

  s.Set(kHelloString);
  EXPECT_EQ(0, strcmp(s.c_string(), kHelloString));

  // Set should work when the input pointer is the same as the one
  // already in the MyString object.
  s.Set(s.c_string());
  EXPECT_EQ(0, strcmp(s.c_string(), kHelloString));

  // Can we set the MyString to NULL?
  s.Set(nullptr);
  EXPECT_STREQ(nullptr, s.c_string());
}
}  // namespace