test: make 'vlib/v/builder/builder_test.v' pass on older Windows versions.

[smalltalkman]

This PR enables v test vlib/v/builder/builder_test.v to pass the test on Windows systems below Win10.

The following are the test results before modification:

v test                      vlib/v/builder/builder_test.v
---- Testing... ----------------------------------------------------------------
 FAIL  2431.316 ms vlib/v/builder/builder_test.v
         retry: 1
      comp_cmd: "D:\gym\test\mingw-w64-packages\mingw-w64-v\src\v-weekly.2024.05\mingw-w64-x86_64-v.exe" -skip-running   -o "D:\gym\test\mingw-w64-packages\mingw-w64-v\tmp\mingw-w64-x86_64-v-weekly.2024.05-1\v_0\tsession_379c_25796335\01HNF86CWK22A0VZCBA79SRX6H\builder_test.exe" "D:\gym\test\mingw-w64-packages\mingw-w64-v\src\v-weekly.2024.05\vlib\v\builder\builder_test.v"
       run_cmd: "D:\gym\test\mingw-w64-packages\mingw-w64-v\tmp\mingw-w64-x86_64-v-weekly.2024.05-1\v_0\tsession_379c_25796335\01HNF86CWK22A0VZCBA79SRX6H\builder_test.exe"
failure code: 1; foutput.len: 732; failure output:
---------------------------------------------------------------------------------------------------- retry: 0 ; max_retry: 0 ; r.exit_code: 1 ; trimmed_output.len: 564
[D:\\gym\\test\\mingw-w64-packages\\mingw-w64-v\\src\\v-weekly.2024.05\\vlib\\v\\builder\\builder_test.v:27] original_file_list_: ['src']
[D:\\gym\\test\\mingw-w64-packages\\mingw-w64-v\\src\\v-weekly.2024.05\\vlib\\v\\builder\\builder_test.v:32] after_run_file_list: ['run_check.exe', 'src']
D:\\gym\\test\\mingw-w64-packages\\mingw-w64-v\\src\\v-weekly.2024.05\\vlib\\v\\builder\\builder_test.v:33: fn test_conditional_executable_removal
   > assert executable !in after_run_file_list
     Left value: run_check.exe
    Right value: ['run_check.exe', 'src']
--------------------------------------------------------------------------------

If time.sleep(200 * time.millisecond) is added to the test file, the test will also have a chance to succeed.

So the root of the problem is: executing os.execute('${os.quoted_path(vexe)} run .') and then executing os.ls(test_path)! will cause the file list to contain non-existent files. These non-existent files will be deleted delayed by Windows.

Here are some links related to the question:

• On Windows, Remove-Item fails intermittently with -Recurse and is unexpectedly asynchronous itself PowerShell/PowerShell#8211
• On Windows, Remove-Item fails intermittently with -Recurse and is unexpectedly asynchronous itself PowerShell/PowerShell#8211
• os: remove 5ms sleep on Windows in (*Process).Wait golang/go#25965
• Fix deletion tests on Windows 10 1903. dotnet/corefx#38186
• Differences between FILE_DELETE_ON_CLOSE and FILE_DISPOSITION_INFORMATION dokan-dev/dokany#883

[spytheman]

Thank you for researching this. I think that it would be better to add a small delay before the os.ls() calls in the builder_test.v file instead, like you also noted.

The reason for that is that the proposed change here, adds an os.exists() call per each entry. I think that is a high cost, and it will still not eliminate the problem (the asynchronous deletion of files on older Windows versions, that breaks the expectations of the test code, according to golang/go#25965 (comment) ).

[smalltalkman]

I think that it would be better to add a small delay before the os.ls() calls in the builder_test.v file instead, like you also noted.

My original idea was to add a delay to solve this problem, but the test results showed that there is still a chance of failure.

The reason for that is that the proposed change here, adds an os.exists() call per each entry. I think that is a high cost, and it will still not eliminate the problem (the asynchronous deletion of files on older Windows versions, that breaks the expectations of the test code, according to golang/go#25965 (comment) ).

Agree this is a time consuming scenario, maybe I should put the exists call into the test file.

I think after_run_file_list := os.ls(test_path)!.filter(os.exists(it)) is also reasonable in such a test scenario.

[spytheman]

Excellent work.