testthatBdd

Mocha-style BDD framework for testthat.

Motivation

While testthat includes a basic describe/it framework, it does not work very well with the provided reporters and does not support the setup blocks (before_each). This package tries to solve these problems by adding setup blocks and providing a new MochaReporter which prints results in the familiar mocha-like style.

Installation

For now, the package is not uploaded to CRAN so you have to install it manually or using renv or devtools:

devtools::install_github("ydistri/testthatBdd")

## or

renv::install("ydistri/testthatBdd")

Usage

Writing tests

In general the usage is the same as mochajs so feel free to refer to their documentation. Here we recount briefly the main features.

Create a test file as usual for testthat, but instead of using test_that, use a combination of describe and it blocks:

library(testthat)
library(testthatBdd)

test_that("addition works", {
  expect_equal(1 + 1, 2)
  expect_equal(10 + 10, 20)
})

## becomes

describe("addition", {

  it("works with small numbers", {
    expect_equal(1 + 1, 2)
  })

  it("works with big numbers", {
    expect_equal(10 + 10, 2)
  })

})

The describe blocks can be nested to further specify the parts of the program.

You can write a common setup block for each it expectation using a before_each. They can be written inside a describe section on any level and run in order from the most general to the most specific before the it code is executed.

library(testthat)
library(testthatBdd)

describe("addition", {

  before_each({
    a <- 1
  })

  describe("with small numbers", {

    it("works", {
      expect_equal(a + a, 2)
    })

  })

  describe("with big numbers", {

    before_each({
      ## make the number bigger!
      a <- a * 10
    })

    it("works", {
      expect_equal(a + a, 20)
    })

  })

})

Skipping tests

To skip an individual test, change the it to xit, it will then be makred as skipped. To skip an entire suite, change describe to xdescribe and all the nested describe and it sections (recursively) will be skipped. You can also use the standard skip_* functions from testthat as usual.

describe("addition", {

  it("works with small numbers", {
    expect_equal(1 + 1, 2)
  })

  xit("works with big numbers", {
    expect_equal(10 + 10, 2)
  })

  it("works with enormous numbers", {
    skip("Platform does not support enormous numbers")
    expect_equal(100000000000 + 100000000000, 2)
  })

})

$ Rscript -e 'devtools::test(reporter = MochaReporter$new())'

  addition
    ✓ works with small numbers
    ? works with big numbers
    ? works with enormous numbers

3 tests, 0 failures, 2 skipped, 0.27 seconds

Reporter

To use the mocha-style reporter, set the reporter to MochaReporter:

$ Rscript -e 'devtools::test(reporter = MochaReporter$new())'

  addition
    with small numbers
      ✓ works
    with big numbers
      ✓ works

2 tests, 0 failures, 0 skipped, 0.1 seconds

The reporter might or might not work nicely with the standard test_that style tests, so use at your own risk.

Limitations

Currently, only the before_each setup section is implemented. before, after and after_each are not implemented.