Strange `magick_image_readpath` fail on some linux CRAN tests

[BradyAJohnston]

I don't know if this is directly related to {magick}, but I've gotten an email from CRAN around some tests on some linux distributions failing. I can't for the life of me figure out what might be going on, as everything on local machines and GHA runners succeed. Something related to path parsing / reading is failing on a couple of CRAN linux distributions. If anyone has any tips on what might be the problem / solution, I would love to know.

CRAN test results

Details

Check Details

Version: 0.2
Check: tests
Result: ERROR
    Running ‘spelling.R’ [0s/1s]
    Running ‘testthat.R’ [1s/2s]
  Running the tests in ‘tests/testthat.R’ failed.
  Complete output:
    > library(testthat)
    > library(figpatch)
    > 
    > test_check("figpatch")
    [ FAIL 1 | WARN 0 | SKIP 0 | PASS 0 ]
    
    ══ Failed tests ════════════════════════════════════════════════════════════════
    ── Error ('test-fig.R:2:3'): Test Reading ──────────────────────────────────────
    <Magick::ErrorMissingDelegate/C++Error/error/condition>
    Error: R: no decode delegate for this image format `' @ error/constitute.c/ReadImage/746
    Backtrace:
         ▆
      1. ├─testthat::expect_error(...) at test-fig.R:2:3
      2. │ └─testthat:::expect_condition_matching(...)
      3. │   └─testthat:::quasi_capture(...)
      4. │     ├─testthat (local) .capture(...)
      5. │     │ └─base::withCallingHandlers(...)
      6. │     └─rlang::eval_bare(quo_get_expr(.quo), quo_get_env(.quo))
      7. └─figpatch::fig("brokenlink")
      8.   └─magick::image_read(path = path)
      9.     ├─base::withCallingHandlers(...)
     10.     └─magick:::magick_image_readpath(path, density, depth, strip, defines)
    
    [ FAIL 1 | WARN 0 | SKIP 0 | PASS 0 ]
    Error: Test failures
    Execution halted
Flavor: [r-devel-linux-x86_64-debian-clang](https://www.r-project.org/nosvn/R.check/r-devel-linux-x86_64-debian-clang/figpatch-00check.html)

Version: 0.2
Check: tests
Result: ERROR
    Running ‘spelling.R’ [0s/0s]
    Running ‘testthat.R’ [1s/1s]
  Running the tests in ‘tests/testthat.R’ failed.
  Complete output:
    > library(testthat)
    > library(figpatch)
    > 
    > test_check("figpatch")
    [ FAIL 1 | WARN 0 | SKIP 0 | PASS 0 ]
    
    ══ Failed tests ════════════════════════════════════════════════════════════════
    ── Error ('test-fig.R:2:3'): Test Reading ──────────────────────────────────────
    <Magick::ErrorMissingDelegate/C++Error/error/condition>
    Error: R: no decode delegate for this image format `' @ error/constitute.c/ReadImage/746
    Backtrace:
         ▆
      1. ├─testthat::expect_error(...) at test-fig.R:2:3
      2. │ └─testthat:::expect_condition_matching(...)
      3. │   └─testthat:::quasi_capture(...)
      4. │     ├─testthat (local) .capture(...)
      5. │     │ └─base::withCallingHandlers(...)
      6. │     └─rlang::eval_bare(quo_get_expr(.quo), quo_get_env(.quo))
      7. └─figpatch::fig("brokenlink")
      8.   └─magick::image_read(path = path)
      9.     ├─base::withCallingHandlers(...)
     10.     └─magick:::magick_image_readpath(path, density, depth, strip, defines)
    
    [ FAIL 1 | WARN 0 | SKIP 0 | PASS 0 ]
    Error: Test failures
    Execution halted

[jeroen]

This is probably related to the version of imagemagick on Debian. It looks like they removed support for some file formats.

It would be really helpful if you can reduce this to a minimal example of R code that triggers the error. I can't infer much from these check logs.

[BradyAJohnston]

I can't reproduce the error myself, so I have no idea if this is actually a reproducible example, but all the test that is failing is basically doing is reading in a .png file.

temp_png <- tempfile(fileext = ".png")
png(filename = temp_png, width = 800, height = 600)
plot(1:10, 1:10, main = "Debug Plot")
dev.off()

magick::image_read(path=temp_png)

In the test, the error message I find a little confusing as it's not actually saying what file format it is failing on.

Error: R: no decode delegate for this image format `' @ error/constitute.c/ReadImage/746

Given that, in theory, it should just be trying a read a .png which already exists (just part of the pacakge), it would raise many more alarm bells if reading PNGs was failing.

In the test, I am just getting the path to the file through system.file, which I thought might be causing an issue, but I'm using mustWork=True and it's not raising any errors, so something is getting passed to magick::image_read() (in theory, just a .png) and that is what is failing.

I am certainly confused by it.