test_that("dim_names", {
  x <- dibble(
    1:6,
    .dim_names = list(
      axis1 = letters[1:2],
      axis2 = tibble::tibble(col1 = 1:3, col2 = 2:4)
    )
  )

  y <- dibble(
    1:12,
    .dim_names = list(
      axis1 = letters[2:3],
      axis2 = tibble::tibble(col1 = 2:4, col2 = 3:5),
      axis3 = letters[3:4]
    )
  )

  expect_equal(
    union_dim_names(list(dimnames(x), dimnames(y))),
    list(
      axis1 = letters[1:3],
      axis2 = tibble::tibble(col1 = 1:4, col2 = 2:5),
      axis3 = letters[3:4]
    )
  )
  expect_equal(
    intersect_dim_names(list(dimnames(x), dimnames(y))),
    list(axis1 = letters[2], axis2 = tibble::tibble(col1 = 2:3, col2 = 3:4))
  )
})