Test a local source package — lazytest

A drop-in replacement for testthat::test_local() that by default reruns only the tests that failed last time.

Usage

lazytest_local(
  path = ".",
  reporter = NULL,
  ...,
  lazytest_reset = FALSE,
  stop_on_failure = TRUE,
  stop_on_warning = FALSE,
  filter = NULL,
  load_package = "source"
)

Arguments

path

Path to directory containing tests.

reporter

Reporter to use to summarise output. Can be supplied as a string (e.g. "summary") or as an R6 object (e.g. SummaryReporter$new()).

See Reporter for more details and a list of built-in reporters.

...

Additional arguments passed to test_dir()

lazytest_reset

Set to TRUE to run all tests, regardless of what the last test results were.

stop_on_failure

If TRUE, throw an error if any tests fail.

stop_on_warning

If TRUE, throw an error if any tests generate warnings.

filter

Must be NULL.

load_package

Strategy to use for load package code:

"none", the default, doesn't load the package.
"installed", uses library() to load an installed package.
"source", uses pkgload::load_all() to a source package. To configure the arguments passed to load_all(), add this field in your DESCRIPTION file:
```
Config/testthat/load-all: list(export_all = FALSE, helpers = FALSE)
```

Value

A list (invisibly) containing data about the test results, like testthat::test_local().

Example

Let's create a package with two boilerplate tests.

withr::local_seed(42)
withr::local_options(usethis.quiet = TRUE)

pkg_parent_dir <- withr::local_tempdir()
pkg_dir <- file.path(pkg_parent_dir, "tea")
usethis::create_package(pkg_dir)
usethis::with_project(path = pkg_dir, {
  usethis::use_testthat()
  usethis::use_test("blop")
  usethis::use_test("blip")
})

If we run the tests, they all pass.

withr::with_dir(
  pkg_dir,
  lazytest::lazytest_local()
)
#> i Testing all tests.
#> v | F W  S  OK | Context
#>
#> / |          0 | blip
#> v |          1 | blip
#>
#> / |          0 | blop
#> v |          1 | blop
#>
#> == Results =====================================================================
#> [ FAIL 0 | WARN 0 | SKIP 0 | PASS 2 ]
#> > Testing all tests next time.

Now if we replace one of the tests with a failing test,

brio::write_lines(
  text =  c(
    'test_that("blop() works", {',
    'expect_equal(2 * 2, 42)',
    '})'
  ),
  path = file.path(pkg_dir, "tests", "testthat", "test-blop.R")
)

and then run the tests,

withr::with_dir(
  pkg_dir,
  lazytest::lazytest_local()
)
#> i Testing all tests.
#> v | F W  S  OK | Context
#>
#> / |          0 | blip
#> v |          1 | blip
#>
#> / |          0 | blop
#> - | 1        0 | blop
#> x | 1        0 | blop
#> --------------------------------------------------------------------------------
#> Failure ('test-blop.R:2:1'): blop() works
#> 2 * 2 (`actual`) not equal to 42 (`expected`).
#>
#>   `actual`:  4.0
#> `expected`: 42.0
#> --------------------------------------------------------------------------------
#>
#> == Results =====================================================================
#> -- Failed tests ----------------------------------------------------------------
#> Failure ('test-blop.R:2:1'): blop() works
#> 2 * 2 (`actual`) not equal to 42 (`expected`).
#>
#>   `actual`:  4.0
#> `expected`: 42.0
#>
#> [ FAIL 1 | WARN 0 | SKIP 0 | PASS 1 ]
#> > Testing the following tests next time:
#> * blop
#> Error: Test failures

a file is created with the failing test name:

brio::read_lines(file.path(pkg_dir, ".lazytest"))
#> [1] "blop"

Next time we run the tests, only this test will be run, until it is fixed at which point all tests are run again to check no failure has been introduced elsewhere.

withr::with_dir(
  pkg_dir,
  lazytest::lazytest_local()
)
#> i Testing only tests that failed last time:
#> * blop
#> v | F W  S  OK | Context
#>
#> / |          0 | blop
#> x | 1        0 | blop
#> --------------------------------------------------------------------------------
#> Failure ('test-blop.R:2:1'): blop() works
#> 2 * 2 (`actual`) not equal to 42 (`expected`).
#>
#>   `actual`:  4.0
#> `expected`: 42.0
#> --------------------------------------------------------------------------------
#>
#> == Results =====================================================================
#> -- Failed tests ----------------------------------------------------------------
#> Failure ('test-blop.R:2:1'): blop() works
#> 2 * 2 (`actual`) not equal to 42 (`expected`).
#>
#>   `actual`:  4.0
#> `expected`: 42.0
#>
#> [ FAIL 1 | WARN 0 | SKIP 0 | PASS 0 ]
#> > Repeating the same tests next time.
#> Error: Test failures