test_that("maybe_contains fails if '.m' isn't a maybe value", {
  for_all(
    a = anything(),
    property = function(a) maybe_contains(a, a) %>% expect_error()
  )
})

test_that("maybe_contains returns FALSE if the maybe value is a nothing", {
  for_all(
    a = anything(),
    property = function(a) nothing() %>% maybe_contains(a) %>% expect_false()
  )
})

test_that("maybe_contains returns TRUE if the contents are equal to 'value'", {
  for_all(
    a = anything(),
    property = function(a) just(a) %>% maybe_contains(a) %>% expect_true()
  )
})