passif: Collate a test expression with a message and a action.

In dtkaplan/checkr2: Exploring ideas for successor to checkr

Description

These functions are simply a way to associate a message with a test. The test itself will be evaluated in line_ functions, arg_ functions, check(), etc. For passif(), failif(), and noteif(), the corresponding result will be generated if the test passes. If the test fails, an "ok" result is generated. But for insist(), a passing test will generate an "ok", and a failing test will generate a "fail". The point of insist() is to avoid the need to use double negative with failif(). The double negative is confusing and error prone to many people.

Usage

passif(test, message = default_message)

failif(test, message = default_message)

noteif(test, message = default_message)

insist(test, message = "")

Arguments

test	an expression written in terms of values found in the pattern-matching bindings
message	a character string containing the message to return.

Details

The message can include components calculated from the bindings. Enclose these in moustaches, e.g. "The {{F}} function is not appropriate for adding." Within a test, the operators == and != in a test have been augmented to deal with language objects such as names. They are translated to be equivalent to "%same_as%". You can refer to the expression being tested with {{expression_string}} and to the test itself as {{test_string}}.

Examples

code <- for_checkr(quote({x <- 2; y <- x^2; z <- x + y}))
my_line <- line_where(code, F == `+`)
check_binding(my_line, `+`(..(x), ..(y)), insist(y == 4, "use 4 for the second argument to +"))
# or equivalently with a double negative ... fail and y != 4
check_binding(my_line, `+`(..(x), ..(y)), failif(y != 4, "use 4 for the second argument to +"))

dtkaplan/checkr2 documentation built on May 17, 2019, 4:01 p.m.