create_file_structure: Create a file structure for tests.

In robertzk/testthatsomemore: A mocking, stubbing, and file testing framework extending testthat

Description

A helper function for creating hierarchical file structures when, e.g., testing functions which rely on presence of files.

An alias for create_file_structure that only allows expressions.

Usage

create_file_structure(files, expr, dir)

within_file_structure(files, expr, dir)

Arguments

files	character or list or NULL. A nested file structure. The names of the list will decide the names of the files, and the terminal nodes should be strings which will populate the file bodies. One can also specify a character (for example, files = c('a','b','c') will create three files with those filenames). By default, files = NULL in which case simply an empty directory will be created.
expr	expression. An expression to evaluate within which the files should exist, but outside of which the files should be unlinked. If missing, the directory of the will be returned. Otherwise, the value obtained in this expression will be returned.
dir	character. The directory in which to create the files. If missing, a temporary directory will be created instead using the built-in tempfile() helper.

Details

For example, when files need to be present for a function we are testing, it would be very cumbersome to create these files manually. Instead, we can do the following:

test_dir <- create_file_structure(list(dir1 = list('file1', file2.r = 'print("Sample R code")'), file3.csv = "a,b,c\n1,2,3"))

with the return value being a test directory containing these structured files.

An additional feature is that expressions can be evaluated within the scope of the hierarchical files existing, with the files getting deleted after the expression executes:

create_file_structure(list(a = "hello\nworld"), cat(readLines(file.path(tempdir, 'a'))[[2]]))

The above will print "world". (tempdir is set automatically within the scope of the expression to the directory that was created for the temporary files.)

Value

the directory in which this file structure exists, if expr is not missing. If expr was provided, its return value will be returned instead.

Examples

## Not run: 
  library(testthat)
  test_dir <- create_file_structure(list(test = 'blah', 'test2'))
  # Now test_dir is the location of a directory containing a file 'test'
  # with the string 'blah' and an empty file 'test2'.

  test_dir <- create_file_structure(list(alphabet = as.list(LETTERS)))
  # Now test_dir is the location of a directory containing a subdirectory
  # 'alphabet' with the files 'A', 'B', ..., 'Z' (all empty).

  test_dir <- create_file_structure(list(a = 'hello'), {
    cat(readLines(file.path(tempdir, 'a')))
  })

## End(Not run)
library(testthat)
expect_output(within_file_structure(list(a = 'hello'), {
  cat(readLines(file.path(tempdir, 'a')))
}), 'hello')
# The above will create a directory with a file named "a" containing the string
# 'hello', print it by reading the file, and then unlink the directory.

robertzk/testthatsomemore documentation built on May 27, 2019, 11:38 a.m.