gxs_selection {xpectr}

Generate testhat expectations from selection

Description

Based on the selection (string of code), a set of testthat expect_* statements are generated.

Example: If the selected code is the name of a data.frame object, it will create an expect_equal test for each column, along with a test of the column names, types and classes, dimensions, grouping keys, etc.

See supported objects in details.

When testing a function that alters non-local variables, consider enabling `copy_env`.

Feel free to suggest useful tests etc. in a GitHub issue!

Addin: insertExpectationsAddin()

Usage

gxs_selection(
  selection,
  indentation = 0,
  tolerance = "1e-4",
  round_to_tolerance = TRUE,
  strip = TRUE,
  sample_n = 30,
  envir = NULL,
  copy_env = FALSE,
  assign_output = TRUE,
  seed = 42,
  test_id = NULL,
  add_wrapper_comments = TRUE,
  add_test_comments = TRUE,
  start_with_newline = TRUE,
  end_with_newline = TRUE,
  out = "insert"
)

Arguments

selection

String of code. (Character)

E.g. "stop('This gives an expect_error test')".

indentation

Indentation of the selection. (Numeric)

tolerance

The tolerance for numeric tests as a string, like "1e-4". (Character)

round_to_tolerance

Whether to round numeric elements to the specified tolerance. (Logical)

This is currently applied to numeric columns and vectors (excluding some lists).

strip

Whether to insert strip_msg() and strip() in tests of side effects. (Logical)

Sometimes testthat tests have differences in punctuation and newlines on different systems. By stripping both the error message and the expected message of non-alphanumeric symbols, we can avoid such failed tests.

sample_n

The number of elements/rows to sample. Set to NULL to avoid sampling.

Inserts smpl() in the generated tests when sampling was used. A seed is set internally, setting sample.kind as "Rounding" to ensure compatibility with R versions < 3.6.0.

The order of the elements/rows is kept intact. No replacement is used, why no oversampling will take place.

When testing a big data.frame, sampling the rows can help keep the test files somewhat readable.

envir

Environment to evaluate in. Defaults to parent.frame().

copy_env

Whether to work in a deep copy of the environment. (Logical)

Side effects will be captured in copies of the copy, why two copies of the environment will exist at the same time.

Disabled by default to save memory but is often preferable to enable, e.g. when the function changes non-local variables.

assign_output

Whether to assign the output of a function call or long selection to a variable. This will avoid recalling the function and decrease cluttering. (Logical)

Heuristic: when the `selection` isn't of a string and contains a parenthesis, it is considered a function call. A selection with more than 30 characters will be assigned as well.

The tests themselves can be more difficult to interpret, as you will have to look at the assignment to see the object that is being tested.

seed

seed to set. (Whole number)

test_id

Number to append to assignment names. (Whole number)

For instance used to create the "output_" name: output_<test_id>.

add_wrapper_comments

Whether to add intro and outro comments. (Logical)

add_test_comments

Whether to add comments for each test. (Logical)

start_with_newline, end_with_newline

Whether to have a newline in the beginning/end. (Logical)

out

Either "insert" or "return".

"insert" (Default)

Inserts the expectations via rstudioapi::insertText().

"return"

Returns the expectations in a list.

These can be prepared for insertion with prepare_insertion().

Details

The following "types" are currently supported or intended to be supported in the future. Please suggest more types and tests in a GitHub issue!

Note: A set of fallback tests will be generated for unsupported objects.

Type	Supported	Notes
Side effects	Yes	Errors, warnings, and messages.
Vector	Yes	Lists are treated differently, depending on their structure.
Factor	Yes
Data Frame	Yes	List columns (like nested tibbles) are currently skipped.
Matrix	Yes	Supported but could be improved.
Formula	Yes
Function	Yes
NULL	Yes
Array	No
Dates	No	Base and lubridate.
ggplot2	No	This may be a challenge, but would be cool!

Value

Either NULL or the unprepared expectations as a character vector.

Author(s)

Ludvig Renbo Olsen, [e-mail]

See Also

Other expectation generators: gxs_function(), initializeGXSFunctionAddin(), insertExpectationsAddin()

Examples

# Attach packages
library(xpectr)

## Not run: 
df <- data.frame('a' = c(1, 2, 3), 'b' = c('t', 'y', 'u'),
                 stringsAsFactors = FALSE)

gxs_selection("stop('This gives an expect_error test!')")
gxs_selection("warning('This gives a set of side effect tests!')")
gxs_selection("message('This also gives a set of side effect tests!')")
gxs_selection("stop('This: tests the -> punctuation!')", strip = FALSE)
gxs_selection("sum(1, 2, 3, 4)")
gxs_selection("df")

tests <- gxs_selection("df", out = "return")
for_insertion <- prepare_insertion(tests)
rstudioapi::insertText(for_insertion)

## End(Not run)