README.md

In rmflight/tt_trace_mre:

testthat trace MRE

a minimal rep example of using trace to count function evals in testthat unit tests

Solution!

Thanks to the pull request from @SteffLocke, you can see that the solution is to make the count variables completely local, and then also make the function that does the counting an anonymous function that is actually local to the trace, which then makes it able to see the local variables in the same environment.

.f1 <- .f2 <- 0

trace(f1, tracer = function() {.f1 <<- .f1 + 1}, print = FALSE)
trace(f2, tracer = function() {.f2 <<- .f2 + 1}, print = FALSE)

test_that("f1 FALSE", {
  f1()
  expect_equal(1, .f1)
  expect_equal(0, .f2)
})

First Try

Based on this, I implemented this:

count_env <- new.env()

count_env$f1 <- count_env$f2 <- 0

trace(f1, tracer = quote(count_env$f1 <- count_env$f1 + 1), print = FALSE)
trace(f2, tracer = quote(count_env$f2 <- count_env$f2 + 1), print = FALSE)

test_that("f1 FALSE", {
  f1()
  expect_equal(1, count_env$f1)
  expect_equal(0, count_env$f2)
})

which has the problem of:

object 'count_env' not found

Second Major Try

test_that("f1 FALSE", {
  count_env <- new.env()

  count_env$f1 <- 0

  trace(f1, tracer = quote(count_env$f1 <<- count_env$f1 + 1), print = FALSE)

  f1()
  expect_equal(1, count_env$f1)
})

Has the same problem.

rmflight/tt_trace_mre documentation built on May 27, 2019, 9:32 a.m.