public void six_day_interval_after_card_is_reviewed_correctly_once()
{
var item = new ReviewItemBuilder().WithLastReviewDate(_clock.Now().AddDays(-10)).WithCorrectReviewStreak(1).Build();
var strategy = new SuperMemo2ReviewStrategy(_clock);
var nextReview = strategy.NextReview(item);
Assert.That(nextReview, Is.EqualTo(item.ReviewDate.AddDays(6)));
}
public void one_day_interval_for_items_without_correct_review()
{
var item = new ReviewItemBuilder().NeverReviewed().Build();
var strategy = new SuperMemo2ReviewStrategy(_clock);
var nextReview = strategy.NextReview(item);
Assert.That(nextReview, Is.EqualTo(_clock.Now()));
}
public void when_is_the_next_review_due()
{
var item = new ReviewItem
{
DifficultyRating = 12,
ReviewDate = new DateTime(2013, 09, 18),
CorrectReviewStreak = 8,
};
var strategy = new SuperMemo2ReviewStrategy();
Debug.WriteLine(strategy.NextReview(item));
}
public void n_plus_2_is_interval_days_since_last_review_times_easiness_factor()
{
var item = new ReviewItemBuilder()
.WithLastReviewDate(_clock.Now().AddDays(-1))
.WitPreviousReviewDate(11)
.WithCorrectReviewStreak(3)
.WithDifficultyRating(DifficultyRating.Easiest)
.Build();
var strategy = new SuperMemo2ReviewStrategy(_clock);
var nextReview = strategy.NextReview(item);
Assert.That(nextReview, Is.EqualTo(item.ReviewDate.AddDays(25)));
}
public void long_interval_for_easy_cards()
{
var difficultyRating = DifficultyRating.Easiest;
var daysSincePreviousReview = 11;
var item = new ReviewItemBuilder()
.WithLastReviewDate(_clock.Now().AddDays(-1))
.WitPreviousReviewDate(daysSincePreviousReview)
.WithDifficultyRating(difficultyRating)
.WithCorrectReviewStreak(3)
.Build();
var strategy = new SuperMemo2ReviewStrategy(_clock);
var nextReview = strategy.NextReview(item);
var expectedInterval = (daysSincePreviousReview - 1) * strategy.DifficultyRatingToEasinessFactor(difficultyRating);
Assert.That(nextReview, Is.EqualTo(item.ReviewDate.AddDays(expectedInterval)));
}