Getting more than 13 last line on test error in Travis-CI

Question

When I build an R package under TravisCI, the last 13 lines are printed out when a test fails. To debug a problem that only occurs under Travis, I need more lines.

Where can I set the number of lines shown in the log?

Added later:

https://github.com/hadley/testthat/commit/f037f463edcccd403502308fd86e32914c6d0d0f

Looks like it is a testthat feature, but I did not understand how to switch it off.

Answer 1

It appears that the "number of trailing lines of test output to reproduce in the log" when running R CMD check can be controlled by the environment variable _R_CHECK_TESTS_NLINES_ which is documented in the R Internals here.

The default value of this environment variable is 13, but if set to 0, "all lines except the R preamble are reproduced".

This answer was prompted by a blog post covering this solution by Yihui Xie.

Answer 2

You need something like this at the end of your travis.yml:

after_failure:
  - ./run.sh dump_logs

(where run.sh is my maintained fork of the initial R-Travis).

That script (just like the travis.sh it came from) have this code:

DumpSysinfo() {                                                                                                                                                                                                     
    echo "Dumping system information."                                                                                                                                                                              
    R -e '.libPaths(); sessionInfo(); installed.packages()'                                                                                                                                                         
}                                                                                                                                                                                                                   

DumpLogsByExtension() {                                                                                                                                                                                             
    if [[ -z "$1" ]]; then                                                                                                                                                                                          
        echo "dump_logs_by_extension requires exactly one argument, got: $@"                                                                                                                                        
        exit 1                                                                                                                                                                                                      
    fi                                                                                                                                                                                                              
    extension=$1                                                                                                                                                                                                    
    shift                                                                                                                                                                                                           
    package=$(find . -maxdepth 1 -name "*.Rcheck" -type d)                                                                                                                                                          
    if [[ ${#package[@]} -ne 1 ]]; then                                                                                                                                                                             
        echo "Could not find package Rcheck directory, skipping log dump."                                                                                                                                          
        exit 0                                                                                                                                                                                                      
    fi                                                                                                                                                                                                              
    for name in $(find "${package}" -type f -name "*${extension}"); do                                                                                                                                              
        echo ">>> Filename: ${name} <<<"                                                                                                                                                                            
        cat ${name}                                                                                                                                                                                                 
    done                                                                                                                                                                                                            
}                                                                                                                                                                                                                   

DumpLogs() {                                                                                                                                                                                                        
    echo "Dumping test execution logs."                                                                                                                                                                             
    DumpLogsByExtension "out"                                                                                                                                                                                       
    DumpLogsByExtension "log"                                                                                                                                                                                       
    DumpLogsByExtension "fail"                                                                                                                                                                                      
} 

and I am sure you can take it from here. The 'new new' Travis surely has a setup for it too.