Type:	Package
Version:	0.2.3
Date:	2023-05-15
Title:	Where Expectations Meet Reality: Realistic Unit Testing
Description:	A framework for unit testing for realistic minimalists, where we distinguish between expected, acceptable, current, fallback, ideal, or regressive behaviour. It can also be used for monitoring third-party software projects for changes.
Depends:	R (≥ 4.0)
Imports:	utils
BugReports:	https://github.com/gagolews/realtest/issues
URL:	https://realtest.gagolewski.com, https://github.com/gagolews/realtest
License:	GPL-2 | GPL-3 [expanded from: GPL (≥ 2)]
Encoding:	UTF-8
RoxygenNote:	7.2.3
NeedsCompilation:	no
Packaged:	2023-05-15 00:25:38 UTC; gagolews
Author:	Marek Gagolewski [aut, cre, cph]
Maintainer:	Marek Gagolewski <marek@gagolewski.com>
Repository:	CRAN
Date/Publication:	2023-05-16 11:30:06 UTC

Where Expectations Meet Reality: Realistic Unit Testing in R

Description

realtest is a framework for unit testing for realistic minimalists, where we distinguish between expected, acceptable, and undesirable behaviour.

Keywords: unit testing, software quality, expectation, undesired behaviour, continuous integration.

License: GNU General Public License version 2 or later.

Author(s)

Marek Gagolewski

See Also

The official online manual of realtest at https://realtest.gagolewski.com/

Test Which Expectations are Met

Description

Performs a unit test and summarises the results.

Usage

E(
  expr,
  ...,
  value_comparer = getOption("realtest_value_comparer", identical),
  sides_comparer = getOption("realtest_sides_comparer", sides_similar),
  postprocessor = getOption("realtest_postprocessor", failstop)
)

Arguments

Details

Each expression in the R language has a range of possible effects. The direct effect corresponds to the value generated by evaluating the expression. Side effects may include errors, warnings, text printed out on the console, etc., see P and R.

Arguments passed via ... whose names do not start with a dot should be objects of class realtest_descriptor (otherwise they are passed to P). They define the prototypes against which the object generated by expr will be tested.

value_comparer and sides_comparer are 2-ary functions that return TRUE if two objects/side effect lists are equivalent and a character string summarising the differences (or any other kind or object) otherwise.

A test case is considered met, whenever value_comparer(prototype[["value"]], object[["value"]]) and sides_comparer(prototype[["sides"]], object[["sides"]]) are both TRUE for some prototype. The comparers may be overridden on a per-prototype basis, though. If prototype[["value_comparer"]] or prototype[["sides_comparer"]] are defined, these are used instead.

Value

The function creates an object of class realtest_result, which is a named list with at least the following components:

• object – an object of class realtest_descriptor, ultimately R(expr),

• prototypes – a (possibly named) list of objects of class realtest_descriptor that were passed via ...,

• matches – a (possibly empty) numeric vector of the indexes of the prototypes matching the object (can be named),

• .dotted.names – copied as-is from the arguments of the same name.

This object is then passed to the postprocessor which itself becomes responsible for generating the output value to be returned by the current function (and, e.g., throwing an error if the test fails).

Author(s)

Marek Gagolewski

See Also

The official online manual of realtest at https://realtest.gagolewski.com/

Related functions: P, R, test_dir

Examples

# the default result postprocessor throws an error on a failed test:
E(E(sqrt(4), P(7)), P(error=TRUE, stdout=TRUE))
E(sqrt(4), 2.0)  # the same as E(sqrt(4), P(2.0))
E(sin(pi), 0.0, value_comparer=all.equal)  # almost-equal
E(
  sample(c("head", "tail"), 1),
  .description="this call has two possible outcomes",
  "head",  # first prototype
  "tail"   # second prototype
)
E(sqrt(-1), P(NaN, warning=TRUE))  # a warning is expected
E(sqrt(-1), NaN, sides_comparer=ignore_differences) # do not test side effects
E(sqrt(-1), P(NaN, warning=NA))  # ignore warnings
E(
  paste0(1:2, 1:3),                  # expression to test - concatenation
  .description="partial recycling",  # info - what behaviour are we testing?
  best=P(                            # what we yearn for (ideally)
    c("11", "22", "13"),
    warning=TRUE
  ),
  pass=c("11", "22", "13"),          # this is the behaviour we have now
  bad=P(error=TRUE)                  # avoid regression
)
e <- E(sin(pi), best=0.0, pass=P(0.0, value_comparer=all.equal),
  .comment="well, this is not a symbolic language after all...")
print(e)

Manually Create a Test Descriptor Prototype

Description

Allows for formulating expectations like 'the desired outcome is c(1, 2, 3), with a warning' or 'an error should occur'.

Usage

P(
  value = NULL,
  error = NULL,
  warning = NULL,
  message = NULL,
  stdout = NULL,
  stderr = NULL,
  value_comparer = NULL,
  sides_comparer = NULL
)

Arguments

Details

If error, warning, message, stdout, or stderr are NULL, then no side effects of particular kinds are included in the output.

The semantics is solely defined by the sides_comparer. E by default uses sides_similar (see its description therein), although you are free to override it manually or via a global option.

Value

A list of class realtest_descriptor with named components:

• value,

• sides (optional) – a list with named elements error, warnings, messages, stdout, and stderr; those which are missing are assumed to be equal to NULL,

• value_comparer (optional) – a function object,

• sides_comparer (optional) – a function object.

Other functions are free to add more named components, and do with them whatever they please.

Author(s)

Marek Gagolewski

See Also

The official online manual of realtest at https://realtest.gagolewski.com/

Related functions: E, R

Examples

# the desired outcome is c(1L, 2L, 3L):
P(1:3)
# expecting c(1L, 2L, 3L), with a warning:
P(1:3, warning=TRUE)
# note, however, that it is the sides_comparer that defines the semantics

Create a Result Descriptor by Recording Effects of an Expression Evaluation

Description

Evaluates an expression and records its direct and indirect effects: the resulting value as well as the information whether any errors, warnings, or messages are generated and if anything is printed on stdout or stderr.

Usage

R(expr, ..., envir = parent.frame())

Arguments

Details

Note that messages, warnings, and errors are typically written to stderr, but these are considered separately here. In other words, when testing expectations with E, e.g., the reference stderr should not include the anticipated diagnostic messages.

There may be other side effects, such as changing the state of the random number generator, modifying options or environment variables, modifying the calling or global environment (e.g., creating new global variables), attaching objects onto the search part (e.g., loading package namespaces), or plotting, but these will not be captured, at least, not by the current version of the realtest package.

Value

A list of class realtest_descriptor, see P, which this function calls. The additional named component expr gives the expression that generated the value. Moreover, args gives a named list of objects that appeared in expr (not including functions called).

If an effect of particular kind does not occur, it is not included in the resulting list. stdout, stderr, and error are at most single strings.

When an error occurs, value is NULL.

Author(s)

Marek Gagolewski

See Also

The official online manual of realtest at https://realtest.gagolewski.com/

Related functions: E, P

Examples

y <- 1:10; R(sum(y^2))
R(cat("a bit talkative, innit?"))
R(sqrt(c(-1, 0, 1, 2, 4)))
R(log("aaaargh"))
R({
    cat("STDOUT"); cat("STDERR", file=stderr()); message("MESSAGE");
    warning("WARNING"); warning("WARNING AGAIN"); cat("MORE STDOUT");
    message("ANOTHER MESSAGE"); stop("ERROR"); y; "NO RETURN VALUE"
})

Example Test Result Postprocessors

Description

Generally, test result postprocessors are used by the E function. failstop calls str(r) and throws an error if an expectation is not met, i.e., when r[["matches"]] is of length 0.

Usage

failstop(r)

Arguments

Details

These are example postprocessors. You are encouraged to write your own ones that will suit your own needs. Explore their source code for some inspirations. It's an open source (and free!) project after all.

For failstop, you can always create a function str.realtest_result implementing the pretty printing of an error message.

Value

Returns r, invisibly.

Author(s)

Marek Gagolewski

See Also

The official online manual of realtest at https://realtest.gagolewski.com/

Example Object and Side Effect Comparers

Description

Example two-argument functions to compare direct or indirect effects of two test descriptors (see P and R). These can be passed as value_comparer and sides_comparer to E.

Usage

ignore_differences(x, y)

sides_similar(x, y)

Arguments

Details

Notable built-in (base R) comparers include identical (the strictest possible) and all.equal (can ignore, amongst others, round-off errors; note that it is an S3 generic).

ignore_differences is a dummy comparer that always returns TRUE. Hence, it does not discriminate between anything.

sides_similar is useful when comparing side effect lists. It defines the following semantics for the prototypical values:

• non-existent, NULL, or FALSE – a side effect must not occur,

• NA – ignore whatsoever,

• TRUE – a side effect occurs, but the details are irrelevant (e.g., 'some warning' as opposed to "NaNs produced")

• otherwise – a character vector with message(s) matched exactly.

You can define any comparers of your own liking: the possibilities are endless. For example:

• a comparer for side effects based on regular expressions or wildcards (e.g., ".not converged.*"),

• a comparer that tests whether all elements in a vector are equal to TRUE,

• a comparer that verifies whether each element in a vector falls into a specified interval,

• a comparer that ignores all the object attributes (possibly in combination with other comparers),

and so forth.

Value

Each comparer should yield TRUE if the test condition is considered met or anything else otherwise. However, it is highly recommended that in the latter case, a single string with a short summary of the differences be returned, as in all.equal.

Author(s)

Marek Gagolewski

See Also

The official online manual of realtest at https://realtest.gagolewski.com/

Summarise and Display Test Results

Description

An example (write your own which will better suit your needs) way to summarise the results returned by test_dir.

Usage

## S3 method for class 'realtest_results_summary'
print(x, label_fail = "fail", ...)

## S3 method for class 'realtest_results'
summary(object, label_pass = "pass", label_fail = "fail", ...)

Arguments

Value

print.realtest_results_summary returns x, invisibly.

summary.realtest_results returns an object of class realtest_results_summary which is a data frame summarising the test results, featuring the following columns:

• call – the name of the function tested,

• match – the name of the first matching prototype, label_pass if it is unnamed or label_fail if there is no match,

• .file (optional) – the name of the source file which defined the expectation,

• .line (optional) – line number,

• .expr (optional) – source code of the whole tested expression.

Author(s)

Marek Gagolewski

See Also

The official online manual of realtest at https://realtest.gagolewski.com/

Related functions: test_dir

Examples

# r <- test_dir("~/R/realtest/inst/realtest")  # some path
# s <- summary(r)  # summary.realtest_results
# print(s)  # print.realtest_results_summary
# stopifnot(!any(s[["match"]]=="fail"))  # halt if there are failed tests

Read and Evaluate Code from an R Script

Description

A simplified alternative to source, which additionally sets some environment variables whilst executing a series of expressions to ease debugging.

Usage

source2(file, local = FALSE)

Arguments

Details

The function sets/updates the following environment variables while evaluating consecutive expressions:

• __FILE__ – path to the current file,

• __LINE__ – line number where the currently executed expression begins,

• __EXPR__ – source code defining the expression.

Value

This function returns nothing.

Author(s)

Marek Gagolewski

See Also

The official online manual of realtest at https://realtest.gagolewski.com/

Examples

# example error handler - report source file and line number
old_option_error <- getOption("error")
options(error=function()
   cat(sprintf(
       "Error in %s:%s.\n", Sys.getenv("__FILE__"), Sys.getenv("__LINE__")
   ), file=stderr()))
# now call source2() to execute an R script that throws some errors...
options(error=old_option_error)  # cleanup

Gather All Test Results From R Scripts

Description

Executes all R scripts in a given directory whose names match a given pattern and gathers all test result in a single list, which you can process however you desire.

The function does not fail if some tests are not met – you need to detect this yourself.

Usage

test_dir(
  path = "tests",
  pattern = "^realtest-.*\\.R$",
  recursive = FALSE,
  ignore.case = FALSE
)

Arguments

Value

Returns a list of all test results (of class realtest_results), each being an object of class realtest_result, see E, with additional fields .file, .line, and .expr, giving the location and the source code of the test instance.

Author(s)

Marek Gagolewski

See Also

The official online manual of realtest at https://realtest.gagolewski.com/

Related functions: source2, summary.realtest_results

Examples

# r <- test_dir("~/R/realtest/inst/realtest")  # some path
# s <- summary(r)  # summary.realtest_results
# print(s)  # print.realtest_results_summary
# stopifnot(!any(s[["match"]]=="fail"))  # halt if there are failed tests