test_1.cc

ConcertProto ExpensiveConcert() {
    ConcertProto concert;
    ArtistProto* artist = concert.mutable_artist();
    artist->set_id(kBeyonceId);
    artist->set_name("Beyonce");
    artist->set_avg_price(200);
    concert.set_capacity(500);
    return concert;
}

TEST(ConcertTest, ComputesPrice) {
    OutcomeProto outcome;
    outcome.set_expected(200 * 500);
    outcome.set_variance(10_000);

    EXPECT_THAT(
        ForecastOutcome(ExpensiveConcert()),
        EqualsProto(outcome));
}