bernoulliTest.cpp

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#include <gtest/gtest.h>
#include <utils/distributions/bernoulli.h>
#include <utils/randomGenerator.h>
#include <stdexcept>

#define NB_ITER 10000

int drawSeveralTimes(int times, double p)
{

    Utils::RandomGenerator *gen;
    gen = new Utils::RandomGenerator;
    Utils::Bernoulli bern(gen, p);
    int successCount = 0;
    for (int i = 0; i < times; i++)
    {
        double result = bern.draw();
        if (result > 0.5)
            successCount++;
    }
    return successCount;
}

TEST(BernoulliTest, draw)
{
    double p = 0.7;
    int successCount = drawSeveralTimes(NB_ITER, p);
    double effectiveProba = (double) successCount / (double) NB_ITER;
    EXPECT_GT(effectiveProba, p*0.9);
    EXPECT_LT(effectiveProba, p*1.1);
}


TEST(BernoulliTest, zeroSuccessRate)
{
    int successCount = drawSeveralTimes(NB_ITER, 0.0);
    EXPECT_EQ(0, successCount);
}

TEST(BernoulliTest, oneSuccessRate)
{
    int successCount = drawSeveralTimes(NB_ITER, 1.0);
    EXPECT_EQ(0, successCount - NB_ITER);
}

TEST(BernoulliTest, throwIfBadProba)
{
    ASSERT_THROW(drawSeveralTimes(NB_ITER, -0.5), std::domain_error);
    ASSERT_THROW(drawSeveralTimes(NB_ITER, 1.5), std::domain_error);
}