Package 'testit'

Assertions with an optional message

Description

The function assert() was inspired by stopifnot(). It emits a message in case of errors, which can be a helpful hint for diagnosing the errors (stopifnot() only prints the possibly truncated source code of the expressions).

The infix operator %==% is simply an alias of the identical() function to make it slightly easier and intuitive to write test conditions. x %==% y is the same as identical(x, y). When it is used inside assert(), a message will be printed if the returned value is not TRUE, to show the values of the LHS (x) and RHS (y) via str(), which can be helpful for you to check why the assertion failed.

Usage

assert(fact, ...)

x %==% y

Arguments

fact	A message for the assertions when any of them fails; treated the same way as expressions in ... if it is not a character string, which means you are not required to provide a message to this function.
...	An R expression; see Details.
x, y	two R objects to be compared

Details

For the ... argument, it should be a single R expression wrapped in {}. This expression may contain multiple sub-expressions. A sub-expression is treated as a test condition if it is wrapped in () (meaning its value will be checked to see if it is a logical vector containing any FALSE values) , otherwise it is evaluated in the normal way and its value will not be checked. If the value of the last sub-expression is logical, it will also be treated as a test condition.

Value

For assert(), invisible NULL if all expressions returned TRUE, otherwise an error is signaled and the user-provided message is emitted. For %==%, TRUE or FALSE.

Note

The internal implementation of assert() is different with the stopifnot() function in R base: (1) the custom message fact is emitted if an error occurs; (2) assert() requires the logical values to be non-empty (logical(0) will trigger an error); (3) if ... contains a compound expression in {} that returns FALSE (e.g., if (TRUE) {1+1; FALSE}), the first and the last but one line of the source code from deparse() are printed in the error message, otherwise the first line is printed; (4) the arguments in ... are evaluated sequentially, and assert() will signal an error upon the first failed assertion, and will ignore the rest of assertions.

Examples

library(testit)
assert("T is bad for TRUE, and so is F for FALSE", {
    T = FALSE
    F = TRUE
    (T != TRUE)  # note the parentheses
    (F != FALSE)
})

assert("A Poisson random number is non-negative", {
    x = rpois(1, 10)
    (x >= 0)
    (x > -1)  # () is optional because it's the last expression
})

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Check if an R expression produces warnings or errors

Description

The two functions has_warning() and has_error() check if an expression produces warnings and errors, respectively.

Usage

has_warning(expr)

has_error(expr, silent = !interactive())

Arguments

expr	an R expression
silent	logical: should the report of error messages be suppressed?

Value

A logical value.

Examples

has_warning(1 + 1)
has_warning(1:2 + 1:3)

has_error(2 - 3)
has_error(1 + "a")
has_error(stop("err"), silent = TRUE)

---

Run the tests of a package in its namespace

Description

The main purpose of this function is to expose the namespace of a package when running tests, which allows one to use non-exported objects in the package without having to resort to the triple colon ::: trick.

Usage

test_pkg(package, dir = c("testit", "tests/testit"))

Arguments

package	the package name
dir	the directory of the test files; by default, it is the directory ‘testit/’ or ‘tests/testit/’ under the current working directory

Details

The tests are assumed to be under the ‘testit/’ or ‘tests/testit/’ directory by default (depending on your working directory is the package root directory or the ‘tests/’ directory). This function also looks for the ‘tests/testit/’ directory under the package installation directory when the user-provided dir does not exist. The test scripts must be named of the form ‘⁠test-*.R⁠’; other R scripts will not be treated as test files (but may also be useful, e.g. you can source() them in tests).

For R CMD check, this means the test R scripts (‘test-*.R’ are under ‘pkg_root/tests/testit/’. The R scripts are executed with sys.source in the namespace of the package to be tested; when an R script is executed, the working directory is the same as the directory containing this script, and all existing objects in the test environment will be removed before the code is executed.

Value

NULL. All test files are executed, unless an error occurs.

Note

All test scripts (‘⁠test-*.R⁠’) must be encoded in UTF-8 if they contain any multibyte characters.

See Also

The testthat package (much more sophisticated).

Examples

## Not run: 
test_pkg("testit")

## End(Not run)

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