Add the necessary infrastructure to enable C++ unit testing
in R packages with Catch and
testthat.
use_catch(dir = getwd())The directory containing an R package.
All of the functions provided by Catch are
available with the CATCH_ prefix -- see
here
for a full list. testthat provides the
following wrappers, to conform with testthat's
R interface:
| Function | Catch | Description |
context | CATCH_TEST_CASE | The context of a set of tests. |
test_that | CATCH_SECTION | A test section. |
expect_true | CATCH_CHECK | Test that an expression evaluates to true. |
expect_false | CATCH_CHECK_FALSE | Test that an expression evalutes to false. |
expect_error | CATCH_CHECK_THROWS | Test that evaluation of an expression throws an exception. |
expect_error_as | CATCH_CHECK_THROWS_AS | Test that evaluation of an expression throws an exception of a specific class. |
In general, you should prefer using the testthat
wrappers, as testthat also does some work to
ensure that any unit tests within will not be compiled or
run when using the Solaris Studio compilers (as these are
currently unsupported by Catch). This should make it
easier to submit packages to CRAN that use Catch.
If you've opted to disable dynamic symbol lookup in your
package, then you'll need to explicitly export a symbol
in your package that testthat can use to run your unit
tests. testthat will look for a routine with one of the names:
C_run_testthat_tests
c_run_testthat_tests
run_testthat_tests
See Controlling Visibility and Registering Symbols in the Writing R Extensions manual for more information.
If you'd like to write your own Catch test runner, you can
instead use the testthat::catchSession() object in a file
with the form:
#define TESTTHAT_TEST_RUNNER
#include <testthat.h>void run()
{
Catch::Session& session = testthat::catchSession();
// interact with the session object as desired
}
This can be useful if you'd like to run your unit tests with custom arguments passed to the Catch session.
If you'd like to use the C++ unit testing facilities provided
by Catch, but would prefer not to use the regular testthat
R testing infrastructure, you can manually run the unit tests
by inserting a call to:
.Call("run_testthat_tests", PACKAGE = <pkgName>)
as necessary within your unit test suite.
Calling use_catch() will:
Create a file src/test-runner.cpp, which ensures that the
testthat package will understand how to run your package's
unit tests,
Create an example test file src/test-example.cpp, which
showcases how you might use Catch to write a unit test,
Add a test file tests/testthat/test-cpp.R, which ensures that
testthat will run your compiled tests during invocations of
devtools::test() or R CMD check, and
Create a file R/catch-routine-registration.R, which ensures that
R will automatically register this routine when
tools::package_native_routine_registration_skeleton() is invoked.
You will also need to:
Add xml2 to Suggests, with e.g. usethis::use_package("xml2", "Suggests")
Add testthat to LinkingTo, with e.g.
usethis::use_package("testthat", "LinkingTo")
C++ unit tests can be added to C++ source files within the
src directory of your package, with a format similar
to R code tested with testthat. Here's a simple example
of a unit test written with testthat + Catch:
context("C++ Unit Test") {
test_that("two plus two is four") {
int result = 2 + 2;
expect_true(result == 4);
}
}
When your package is compiled, unit tests alongside a harness
for running these tests will be compiled into your R package,
with the C entry point run_testthat_tests(). testthat
will use that entry point to run your unit tests when detected.
Catch, the library used to enable C++ unit testing.