test_that("checkValidStartLife works correctly", {
  M <- matrix(1:4, nrow = 2)

  startLife <- 1
  expect_silent(checkValidStartLife(startLife, M))

  startLife <- c(3, 4)
  expect_error(checkValidStartLife(startLife, M))

  startLife <- 5
  expect_error(checkValidStartLife(startLife, M))

  startLife <- c(0.4, 0.6)
  expect_silent(checkValidStartLife(startLife, M, start_vec = TRUE))

  startLife <- c(0, 0.4, 0.6)
  expect_error(checkValidStartLife(startLife, M, start_vec = TRUE))
})