Possible rlang/reticulate issue causing test traceback failure in R CMD CHK

[pbulsink]

Hello

We have a periodic failure in build checks at scasanova/f1dataR an issue in our reticulate/R interface. I don't think the specifics of that are important, but what happens in the build when we have this issue is a failure to properly present any traceback:

  [ FAIL 2 | WARN 0 | SKIP 0 | PASS 87 ]

  ══ Failed tests ════════════════════════════════════════════════════════════════
  Error in if (is.null(x[["trace"]]) || trace_length(x[["trace"]]) == 0L) { : 
    missing value where TRUE/FALSE needed
  Calls: test_check ... vapply -> FUN -> paste0 -> format -> format.expectation
  Execution halted

Test traceback failure can be observed at this link: https://github.com/SCasanova/f1dataR/actions/runs/5385032984/jobs/9773619355

As far as I can tell this issue randomly pops up after failures in our reticulate to R usage and is not reproducible wrt os or R version (> 4.0). The exact cause of the failure is difficult to know because of the failure of traceback.

If you feel this isn't related to rlang please feel free to close.

[harupy]

Same here: https://github.com/mlflow/mlflow/actions/runs/5473056182/jobs/9966022819?pr=8978

Error in if (is.null(x[["trace"]]) || trace_length(x[["trace"]]) == 0L) { : 
  missing value where TRUE/FALSE needed
Calls: source ... vapply -> FUN -> paste0 -> format -> format.expectation
Execution halted
══ Failed tests ════════════════════════════════════════════════════════════════

[lionel-]

cc @t-kalinowski

[t-kalinowski]

I've observed something similar intermittently, but don't have a reprex currently and haven't had a chance to investigate yet. I think it's most likely due to dueling calling handlers between testthat and reticulate.

Running the code being tested directly, outside a testthat context, will show the actual error message.

[t-kalinowski]

Attempting a reprex, I'm seeing a different but related issue w/ testthat injecting rlang condition handlers that error on R conditions wrapping Python Exceptions:

test_that("test", {
  skip_if_no_python()

  expect_no_error({
    py_fn <- py_run_string("def fn(): raise Exception()")$fn
    py_fn()
  })
})

produces:

── Error (Line 4): test ────────────────────────────────────────────────────────
Error in `cnd_type(cnd)`: `cnd` is not a condition object.
Backtrace:
     ▆
  1. ├─testthat::expect_no_error(...)
  2. │ └─testthat:::expect_no_(...)
  3. │   └─testthat:::quasi_capture(enquo(object), NULL, capture)
  4. │     ├─testthat (local) .capture(...)
  5. │     │ └─rlang::try_fetch(...)
  6. │     │   ├─base::tryCatch(...)
  7. │     │   │ └─base (local) tryCatchList(expr, classes, parentenv, handlers)
  8. │     │   │   └─base (local) tryCatchOne(expr, names, parentenv, handlers[[1L]])
  9. │     │   │     └─base (local) doTryCatch(return(expr), name, parentenv, handler)
 10. │     │   └─base::withCallingHandlers(...)
 11. │     └─rlang::eval_bare(quo_get_expr(.quo), quo_get_env(.quo))
 12. ├─reticulate (local) py_fn()
 13. │ └─reticulate:::py_call_impl(callable, call_args$unnamed, call_args$named) at reticulate/R/python.R:1437:4
 14. ├─base::stop(`<python.builtin.Exception>`)
 15. ├─rlang (local) `<fn>`(`<python.builtin.Exception>`)
 16. │ └─handlers[[1L]](cnd)
 17. │   ├─base::paste0(...)
 18. │   ├─testthat:::indent_lines(rlang::cnd_message(cnd, prefix = TRUE))
 19. │   │ ├─base::paste0("  ", gsub("\n", "\n  ", x))
 20. │   │ └─base::gsub("\n", "\n  ", x)
 21. │   │   └─base::is.factor(x)
 22. │   └─rlang::cnd_message(cnd, prefix = TRUE)
 23. │     └─rlang:::cnd_message_format_prefixed(cnd, ..., parent = FALSE)
 24. │       └─rlang::cnd_type(cnd)
 25. └─rlang::abort(message = message)

A more minimal reprex:

ex <-reticulate::py_eval("Exception('msg')")

# ex is a condition, fulfills the condition contract
inherits(ex, "condition")
#> [1] TRUE
cat(conditionMessage(ex))
#> Exception: msg
#> Run `reticulate::py_last_error()` for details.
conditionCall(ex)
#> NULL

# cnd_type(ex) signals an error
rlang::cnd_type(ex)
#> Error in `rlang::cnd_type()`:
#> ! `cnd` is not a condition object.
#> Backtrace:
#>     ▆
#>  1. ├─rlang::cnd_type(ex)
#>  2. └─rlang::abort(message = message)

^{Created on 2023-07-06 with reprex v2.0.2}

[t-kalinowski]

The actual error is being raised from testthat: https://github.com/r-lib/testthat/blob/53cd6dd53eeaadd4229c4702f380ca283ec74b52/R/expectation.R#L165

My best guess is that trace_length() is returning an NA or length 0 vector, which is causing || to error.

[pbulsink]

As this looks like a testthat issue I've raised it there.

[t-kalinowski]

This was fixed with https://github.com/r-lib/rlang/issues/1637; this issue can be closed.

[lionel-]

Thanks @t-kalinowski!