proportion-expectations: Expectations: proportions

Description

These test the proportion of data in a data frame satisfying some condition. The generic functions, expect_prop_lte() and expect_prop_gte(), can be used with any arbitrary function. The chk_*() functions, like chk_values(), are useful in this regard.

Usage

expect_prop_lte(
  var,
  func,
  prop,
  flt = TRUE,
  data = get_testdata(),
  args = list(),
  func_desc = NULL
)
expect_prop_gte(
  var,
  func,
  prop,
  flt = TRUE,
  data = get_testdata(),
  args = list(),
  func_desc = NULL
)
expect_prop_nmiss(
  var,
  prop,
  miss = getOption("testdat.miss"),
  flt = TRUE,
  data = get_testdata()
)
expect_prop_values(var, prop, ..., flt = TRUE, data = get_testdata())

Value

expect_*() functions are mainly called for their side effects. The expectation signals its result (e.g. "success", "failure"), which is logged by the current test reporter. In a non-testing context the expectation will raise an error with class expectation_failure if it fails.

Arguments

var: An unquoted column name to test.
func: A function to use for testing that takes a vector as the first argument and returns a logical vector of the same length showing whether an element passed or failed.
prop: The proportion of the data frame expected to satisfy the condition.
flt: <data-masking> A filter specifying a subset of the data frame to test.
data: A data frame to test. The global test data is used by default.
args: A named list of arguments to pass to func.
func_desc: A human friendly description of func to use in the expectation failure message.
miss: A vector of values to be treated as missing. The testdat.miss option is used by default.
...: Vectors of valid values.

Details

Given the use of quasi-quotation within these functions, to make a new functions using one of the generics such as expect_prop_gte() one must defuse the var argument using the embracing operator {{ }}. See the examples sections for an example.

Examples

Run this code

sales <- data.frame(
  sale_id = 1:5,
  date = c("20200101", "20200101", "20200102", "20200103", "2020003"),
  sale_price = c(10, 20, 30, 40, -1),
  book_title = c(
    "Phenomenology of Spirit",
    NA,
    "Critique of Practical Reason",
    "Spirit of Trust",
    "Empiricism and the Philosophy of Mind"
  ),
  stringsAsFactors = FALSE
)

# Create a custom expectation
expect_prop_length <- function(var, len, prop, data) {
  expect_prop_gte(
    var = {{var}}, # Notice the use of the embracing operator
    func = chk_max_length,
    prop = prop,
    data = data,
    args = list(len = len),
    func_desc = "length_check"
  )
}

# Use it to check that dates are mostly <= 8 char wide
expect_prop_length(date, 8, 0.9, sales)

# Check price values mostly between 0 and 100
try(expect_prop_values(sale_price, 0.9, 1:100, data = sales))