foo <- function(a, b) {
  # Returns a + b

  ### BEGIN SOLUTION
  return(a + b)
  ### END SOLUTION
}

squares <- function(n) {
  # Compute the squares of the numbers from 1 to n.

  ### BEGIN SOLUTION

  # Put correct code here. This code is removed for the student version, but is
  # used to confirm that your tests are valid.
  if (n <= 0) {
    stop("n must be positive")
  }
  x <- 1:n
  return(x * x)

  ### END SOLUTION
}

testthat::test_that("squares function works as expected", {
  # test the result is an integer vector of length 10
  testthat::expect_vector(squares(10), ptype = integer(), size = 10)
  # check for a specific n=3
  testthat::expect_equal(squares(3), c(1, 4, 9))
  # use 'tolerance' when there are slight floating point errors
  testthat::expect_equal(squares(2), c(1, 4.000001), tolerance = 0.002)
})

# make sure the error contains the word 'positive' for a negative n
testthat::test_that("squares function raises errors", {
  testthat::expect_error(squares(-1), "*positive*", ignore.case = TRUE)
})

### BEGIN HIDDEN TESTS

# students will NOT see this extra test
testthat::expect_equal(squares(10), c(1, 4, 9, 16, 25, 36, 49, 64, 81, 100))
### END HIDDEN TESTS