test_that("is_degree", {
    expect_true(is_degree(0L))
    expect_true(is_degree(1L))
    expect_true(is_degree(0L:1L))
    expect_true(is_degree(0.5))
    expect_true(is_degree(c(0:100 / 100)))
    expect_true(is_degree(matrix(c(0:99 / 99), nrow = 25)))
    expect_true(is_degree(NA_real_, na_rm = TRUE))

    expect_false(is_degree(c()))
    expect_false(is_degree("0"))
    expect_false(is_degree(list(a=0)))
    expect_false(is_degree(2L))
    expect_false(is_degree(1.1))
    expect_false(is_degree(NA_real_, na_rm = FALSE))
    expect_false(is_degree(NA_character_, na_rm = TRUE))
})