cpp-game-engine/engine/test/fps_counter_test.cxx

//
//  fps_counter_test.cxx
//  engine-test
//
//  Created by Sam Jaffe on 7/7/19.
//  Copyright © 2019 Sam Jaffe. All rights reserved.
//

#include <gmock/gmock.h>

#include "game/engine/fps_counter.hpp"
#include "game/engine/text_engine.hpp"

#include "mock_renderer.h"

#ifdef __APPLE__
namespace env { namespace detail {
  extern void bundle(std::string const &);
}}
#endif

using testing::IsEmpty;
using testing::SizeIs;

struct FpsCounterTest : testing::Test {
  void SetUp() override;
  void TearDown() override;
  std::shared_ptr<graphics::manager> manager;
  std::shared_ptr<engine::text_engine> engine;
};

void FpsCounterTest::SetUp() {
#ifdef __APPLE__
  env::detail::bundle("leumasjaffe.engine-test");
#endif
  manager.reset(new stub_manager_impl);
  engine.reset(new engine::text_engine("font", manager));
}

void FpsCounterTest::TearDown() {
  engine.reset();
  manager.reset();
}

TEST_F(FpsCounterTest, CanConstructCtrNoExcept) {
  EXPECT_NO_THROW(engine::fps_counter(engine, 5));
}

TEST_F(FpsCounterTest, CanFrameNoExcept) {
  engine::fps_counter counter(engine, 5);
  env::clock::duration ms_100{100000000LL};
  EXPECT_NO_THROW(counter.set_frame_step(ms_100));
}

// TODO (sjaffe): Give ability to specifiy change_after_ in ctor?
TEST_F(FpsCounterTest, NoGlyphsUntilCrossesChangeThresh) {
  engine::fps_counter counter(engine, 5);
  env::clock::duration ms_100{100000000LL};
  EXPECT_THAT(counter.glyphs(), IsEmpty());
  counter.set_frame_step(ms_100);
  EXPECT_THAT(counter.glyphs(), IsEmpty());
}

// TODO (sjaffe): Test different precisions
// TODO (sjaffe): Test <10 fps and >=100 fps
TEST_F(FpsCounterTest, ProducesEnoughDigitsForPrecision) {
  engine::fps_counter counter(engine, 5);
  env::clock::duration ms_100{100000000LL};
  for (int i = 0; i < 10; ++i) {
    counter.set_frame_step(ms_100);
  }
  EXPECT_THAT(counter.glyphs(), SizeIs(8));
}

struct mock_renderer : public stub_renderer {
  MOCK_METHOD1(draw, void(graphics::object const &));
};

TEST_F(FpsCounterTest, RenderCallInvokesOneDrawPerGlyph) {
  // Set up expectations
  using testing::_;
  mock_renderer renderer;
  EXPECT_CALL(renderer, draw(_)).Times(8);

  // Set up counter
  engine::fps_counter counter(engine, 5);
  env::clock::duration ms_100{100000000LL};
  for (int i = 0; i < 10; ++i) {
    counter.set_frame_step(ms_100);
  }
  counter.render(renderer);
}