test_that(
    "combinatorial test with d = 3. combinatorial.", {
        # given
        n <- 5
        d <- 3
        set.seed(853)
        phenotypes <- sprintf("p%s", 1:d)
        y <- matrix(
            runif(d * n),
            ncol = d
        )
        colnames(y) <- phenotypes
        correct_colnames <- c("p1*p1", "p2*p1", "p2*p2", "p3*p1", "p3*p2", "p3*p3")
        # when
        result <- mapit_struct_names(t(y))
        # then
        expect_equal(result, correct_colnames)
    }
)

test_that(
    "combinatorial test with d = 1. combinatorial.", {
        # given
        n <- 5
        d <- 1
        set.seed(853)
        phenotypes <- sprintf("p%s", 1:d)
        y <- matrix(
            runif(d * n),
            ncol = d
        )
        colnames(y) <- phenotypes
        correct_colnames <- c("p1")
        # when
        result <- mapit_struct_names(t(y))
        # then
        expect_equal(result, correct_colnames)
    }
)