Fix path handling to work with Windows and add tests for it

[dpvc]

This PR makes it possible to run MathJax via node in Windows (without needing to use a unix subsystem). The main issue is, as usual, the use of \ rather than / in Windows path names, so we introduce a new function in the context object that converts Windows (absolute) paths to unix-style paths when needed, and use this whenever __dirname or import.meta.url or similar values are used. That way, the management of paths can use / as it currently does.

In addition, the context setup for context.os now handles the situation within node as well (it used to always return undefined). This is done using the process.platform value to make to the generic Unix, Windows, and MacOS values. I wasn't sure how to treat cygwin, but have decided to set it to Windows, since it should not hurt to do the path adjustment there, and my understanding is that cygwin can use Windows paths, so it might be useful to do the translation anyway.

The context tests are adjusted for the new values, and I've added several new files to handle testing Windows and to get full coverage in the tests.

This resolves issue mathjax/MathJax#3439.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.72%. Comparing base (afaf1ea) to head (d73a2a1).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #1361   +/-   ##
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  Coverage    86.72%   86.72%           
========================================
  Files          337      337           
  Lines        84145    84174   +29     
  Branches      3140     3145    +5     
========================================
+ Hits         72971    73000   +29     
  Misses       11174    11174           

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[dpvc]

I have added a commit that updates the build tools to work in Windows as well. As always, the main issue is the \ vs. / problem. This is most important in build, where the file names in the import command in the lib directory would otherwise have \ in them, which node will interpret as string escapes, so that something like ..\util\Styles.js would try to use \u as indicating a unicode character and choke in the til that comes after it.

You also need to tell Windows to use a shell for execSync() and spawn(). In most cases, shell: true will work, but in makeAll, because the arguments are in '...', that is a problem for Windows, because the standard shell uses "..." to quote arguments, and '...' are take to be part of the argument. I could have switched to "...", but that would mean more unix steel characters would have to be quoted, and I didn't want to have to do that, and didn't want to have to deal with potentially different shell escapes for Windows. Instead, I specify the bash shell explicitly for Windows. I think that should be OK, though it relies on git being installed.

Since our package scripts expect to be run in bash, a Windows shell user will need to specify

npm config set script-shell "C:\\Program Files\\git\\bin\\bash.exe"

before running our build scripts.

Finally, I changed the package scripts to use a literal ESC character, so that it works in Windows as well as unix.

[dpvc]

I should mention that this was discussed in the MathJax User's forum, where the original poster has confirmed (after a bit of back and forth) that the changes worked for him.

[zorkow]

I ran into two issues building under Win10 with node 25 (latest version).

• When running pnpm build

> @mathjax/[email protected] build C:\Users\vxs\git\MathJax-src
> pnpm -s build-mjs

'log' is not recognized as an internal or external command,
operable program or batch file.
 ELIFECYCLE  Command failed with exit code 1.

• Running the build commands without logging:

node components/bin/link-full
pnpm tsc --project tsconfig/mjs.json
pnpm tsc --project tsconfig/worker.json
pnpm copyfiles -u 1 'ts/a11y/sre/*.html' 'ts/a11y/sre/require.*' mjs
pnpm copyfiles -u 1 'ts/input/asciimath/legacy/**/*' mjs
pnpm copyfiles -u 1 ts/input/mathml/mml3/mml3.sef.json mjs
pnpm copyfiles -u 2 components/bin/package.json mjs

pnpm rimraf -g components/mjs/**/lib
pnpm rimraf bundle
node components/bin/makeAll --mjs --terse components/mjs
echo '{\n  \"type\": \"commonjs\"\n}' > bundle/package.json

the penultimate command fails during webpacking with

[DEP0190] DeprecationWarning: Passing args to a child process with shell option true can lead to security vulnerabilities, as the arguments are not escaped, only concatenated.

Although this is only a warning it still seems to kill the bundling.

I Currently I assume that it does not like the options from
line 130 but I have not yet investigated further.

[dpvc]

When running pnpm build
...
'log' is not recognized as an internal or external command,
operable program or batch file.

Did you set the script-shell configuration as mentioned above? This is due to the fact that a number of our scripts, like the logging script, rely on the shell being bash, not the default windows command shell. You need to do

npm config set script-shell "C:\\Program Files\\git\\bin\\bash.exe"

or something similar (depending on where your copy of bash is). Before this will work.

I have run it successfully in my Windows VM, and the original poster has run it after making the needed patches, so I'm pretty sure this works.