Forward stdout/stderr from parallel tests

[hadley]

(100% pure claude code)

I guess the question here is do we want to forward as we update the number of tests, or only at the end when we report the test failures etc. I can see arguments for either

Fixes #2095

[gaborcsardi]

I am afraid that it will take a bit more than this. We need to read out the output as we go, (nearly) immediately as it happens, because otherwise the pipe between the processes will be full and the subprocess stops.

This is possibly already happening in the CI jobs that are stuck.

[hadley]

I was afraid that this solution was too simple.

[gaborcsardi]

I have a simple solution, the output looks like this:

❯ testthat::test_local(filter = "b")
Starting 2 test processes
✔ | F W  S  OK | Context
⠇ [ FAIL 0 | WARN 0 | SKIP 0 | PASS 0 ] @ bare                                                                                                                  
test-bare.R: hello!
✔ |          5 | bare                                                                                                                                           
✔ |         12 | expect-invisible                                                                                                                               
⠹ [ FAIL 0 | WARN 0 | SKIP 0 | PASS 19 ] @ describe                                                                                                             
test-describe.R:   [1]   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16  17  18
test-describe.R:  [19]  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36
test-describe.R:  [37]  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53  54
test-describe.R:  [55]  55  56  57  58  59  60  61  62  63  64  65  66  67  68  69  70  71  72
test-describe.R:  [73]  73  74  75  76  77  78  79  80  81  82  83  84  85  86  87  88  89  90
test-describe.R:  [91]  91  92  93  94  95  96  97  98  99 100
✔ |          8 | describe                                                                                                                                       
✔ |         15 | quasi-label                                                                                                                                    
✔ |         38 | reporter-debug                                                                                                                                 
                                                                                                                                                                
══ Results ═════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════
Duration: 1.7 s

[ FAIL 0 | WARN 0 | SKIP 0 | PASS 78 ]

I lumped together the standard output and error, and also didn't make an effort to hide the progress bar before printing the output. There is a message() in test-bare.R and an print(1:100) in test-describe.R.

Considering that this is mainly for print-debugging, this might be good enough. It is not any better for non-parallel runs, I think.

[gaborcsardi]

• Add tests
• Remove the print debugging
• Fix parallel-setup test case
• Fix parallel-startup test case

[hadley]

Yeah, that looks perfect to me. Thanks!

[gaborcsardi]

@hadley This is done, I think, if you want to take another look. (I can't formally request a review from you, I guess because you are the original author?)