R/expectations.R

In r-lib/mockery: Mocking Library for R

#' Expectation: does the given call match the expected?
#'
#' Together with \code{\link{mock}} can be used to verify whether the
#' call expression (\code{\link{expect_call}}) and/or argument values
#' (\code{\link{expect_args}}) match the expected.
#'
#' With \code{expect_called} you can check how many times has the mock
#' object been called.
#'
#' @param mock_object A \code{\link{mock}} object.
#' @param n Call number or total number of calls.
#' @param expected_call Expected call expression; will be compared unevaluated.
#' @param ... Arguments as passed in a call.
#'
#' @examples
#' library(testthat)
#'
#' # expect call expression (signature)
#' m <- mock()
#' with_mock(summary = m, summary(iris))
#'
#' # it has been called once
#' expect_called(m, 1)
#'
#' # the first (and only) call's arguments matches summary(iris)
#' expect_call(m, 1, summary(iris))
#'
#' # expect argument value
#' m <- mock()
#' a <- iris
#' with_mock(summary = m, summary(object = a))
#' expect_args(m, 1, object = a)
#' # is an equivalent to ...
#' expect_equal(mock_args(m)[[1]], list(object = a))
#'
#' @name call-expectations
#'
NULL



#' @export
#' @rdname call-expectations
#'
#' @importFrom testthat expect
expect_call <- function (mock_object, n, expected_call) {
  stopifnot(is_mock(mock_object))

  expect(
    0 < n && n <= length(mock_object),
    sprintf("call number %s not found in mock object", toString(n))
  )

  expected_call <- substitute(expected_call)
  mocked_call <- mock_calls(mock_object)[[n]]

  format_call <- function (x) paste(trimws(deparse(x)), collapse = ' ')
  
  expect(
    identical(mocked_call, expected_call),
    sprintf("expected call %s does not mach actual call %s.",
            format_call(expected_call), format_call(mocked_call))
  )

  invisible(TRUE)
}


#' @export
#' @rdname call-expectations
#'
#' @importFrom testthat expect expect_equal
expect_args <- function (mock_object, n, ...)
{
  stopifnot(is_mock(mock_object))

  expect(
    0 < n && n <= length(mock_object),
    sprintf("arguments list number %s not found in mock object", toString(n))
  )

  expected_args <- list(...)
  actual_args   <- mock_args(mock_object)[[n]]
  
  expect_equal(length(actual_args), length(expected_args),
               info = 'number of expected args does not match the actual')
  
  for (i in seq_along(actual_args)) {
    expect_equal(
      actual_args[[i]],
      expected_args[[i]],
      label = paste(ordinal(i), 'actual argument'),
      expected.label = paste(ordinal(i), 'expected argument')
    ) 
  }

  invisible(TRUE)
}


ordinal <- function (x) 
{
  stopifnot(is.integer(x), x > 0, length(x) == 1)
  if (x %in% 11:13)
    return(paste0(x, 'th'))

  as_string  <- as.character(x)
  last_digit <- substring(as_string, nchar(as_string))
  suffix <- switch(last_digit,
         `1` = 'st',
         `2` = 'nd',
         `3` = 'rd',
               'th')
  paste0(as_string, suffix)
}


#' @export
#' @rdname call-expectations
expect_called <- function (mock_object, n)
{
  stopifnot(is_mock(mock_object))

  expect(
    length(mock_object) == n,
    sprintf("mock object has not been called %s time%s", toString(n),
            (if(n>1) "s" else ""))
  )
}