R: Examples for 'assertthat::assert

### ** Examples

x <- 1
# assert_that() generates errors, so can't be usefully run in
# examples
## Not run: 
##D assert_that(is.character(x))
##D assert_that(length(x) == 3)
##D assert_that(is.dir("asdf"))
##D y <- tempfile()
##D writeLines("", y)
##D assert_that(is.dir(y))
##D assert_that(FALSE, msg = "Custom error message")
## End(Not run)

# But see_if just returns the values, so you'll see that a lot
# in the examples: but remember to use assert_that in your code.
see_if(is.character(x))

[1] FALSE
attr(,"msg")
[1] "x is not a character vector"

see_if(length(x) == 3)

[1] FALSE
attr(,"msg")
[1] "length(x) not equal to 3"

see_if(is.dir(17))

[1] FALSE
attr(,"msg")
[1] "path is not a string (a length one character vector)."

see_if(is.dir("asdf"))

[1] FALSE
attr(,"msg")
[1] "Path 'asdf' does not exist"

see_if(5 < 3, msg = "Five is not smaller than three")

[1] FALSE
attr(,"msg")
[1] "Five is not smaller than three"

Examples for 'assertthat::assert_that'

Assert that certain conditions are true.