cpp-descriptive-pointers/test/maybe_null_test.cxx

//
//  maybe_null.t.h
//  pointers
//
//  Created by Sam Jaffe on 12/2/16.
//

// Define DEBUG in order to obtain certain checks...
#ifndef DEBUG
#define DEBUG
#endif

#include "pointers/maybe_null.hpp"

#include <memory>

#include <gmock/gmock.h>

#include "test_stubs.h"

TEST(MaybeNullPtrTest, NullPtrEvaluatesAsFalse) {
  maybe_null<std::shared_ptr<int>> mn{nullptr};
  EXPECT_FALSE(mn);
}

TEST(MaybeNullPtrTest, ValidPtrEvaluatesAsTrue) {
  maybe_null<std::shared_ptr<int>> mn{std::make_shared<int>(0)};
  EXPECT_TRUE(mn);
}

TEST(MaybeNullPtrTest, DereferencingNullPtrThrows) {
  maybe_null<std::shared_ptr<int>> mn{nullptr};
  EXPECT_THROW(*mn, unchecked_pointer_exception);
}

TEST(MaybeNullPtrTest, ContainsInnerPtrForEquality) {
  std::shared_ptr<int> i{new int};
  maybe_null<std::shared_ptr<int>> n{i};
  EXPECT_TRUE(n);
  EXPECT_THAT(n.get(), i.get());
  EXPECT_THAT(*n, *i);
}

TEST(MaybeNullPtrTest, UpcastedPointerStillEqual) {
  struct base {};
  struct derived : public base {};
  derived d;
  maybe_null<derived *> m{&d};
  maybe_null<base *> b = m;
  EXPECT_THAT(b.get(), m.get());
}

TEST(MaybeNullPtrTest, CanModifyInnerValue) {
  std::shared_ptr<int> i{new int{5}};
  maybe_null<std::shared_ptr<int>> n{i};
  EXPECT_TRUE(n);
  EXPECT_THAT(*n, 5);
  *n = 4;
  EXPECT_TRUE(n);
  EXPECT_THAT(*i, 4);
}

TEST(MaybeNullPtrTest, DoesNotDeleteRawPtr) {
  bool has_delete{false};
  destructor_sentinal * test_struct = new destructor_sentinal{has_delete};
  maybe_null<destructor_sentinal *>{test_struct};
  EXPECT_FALSE(has_delete);
  delete test_struct;
  EXPECT_TRUE(has_delete);
}