pickler

The goal of pickler is to provide Gherkin syntax helpers for testthat’s describe() and it() functions.

Installation

You can install the development version of pickler from GitHub with:

# install.packages("pak")
pak::pak("mjfrigaard/pickler")

library(pickler)

if (!require(pak)) {
  install.packages("pak",
    repos = "http://cran.us.r-project.org"
  )
}
pak::pkg_install("r-lib/testthat", upgrade = TRUE, ask = FALSE)
library(testthat)

Example

Behavior-driven development (BDD) starts with a clearly defined business goal (or goals). Developers will collaborate with users to ensure each feature is aligned with a goal and is captured in a plain-language, real-life scenario. Scenarios are used to write tests to verify the feature behaves as expected, creating up-to-date documentation on how the software works (and what it can do).

pickler automates this process by compiling the features (in describe()), scenarios (in it() and test_that()), and expectations (expect_*() functions) into a FEATURE.md markdown report.

testthat’s BDD functions allow for more explicit descriptions of tests:

describe(description = "verify that you implement the right things", code = {
  it(description = "ensure you do the things right", code = {
    expect_true(TRUE)
  })
})
#> Test passed

pickler provides a set of helpers for writing Gherkin-style features, backgrounds and scenarios which can be placed in describe() and it():

describe(
  feature(
    title = "My thing's feature",
    as_a = "user of this thing",
    i_want = "to verify that I implemented the right thing",
    so_that = "I'm sure I did the thing right"
  ), code = {
  it(
    scenario(
        title = "Example of using thing",
        given = "My package is installed and loaded",
        when = "I do something",
        then = "the right thing happens"
      ), code = {
    expect_true(TRUE)
  })
})
#> Test passed

pickler functions can also it can be dropped into the desc argument of test_that():

test_that(
  scenario(
        title = "Example of thing",
        given = "My package is installed and loaded",
        when = "I do something",
        then = "the right thing happens"
      ),
  code = {
    expect_true(TRUE)
  }
)
#> Test passed

Check out the Getting Started vignette to learn more.