Better method for managing python black package

[nedtwigg]

We are able to call black by shelling out to it on the system path, and we are able to cache its results by enforcing a version check on the binary. However, if it isn't on the path, or the version is wrong, we just show a helpful error message and let the user figure it out from there:

spotless/lib/src/main/java/com/diffplug/spotless/python/BlackStep.java

Lines 65 to 66 in 608e128

	.fixCantFind("Try running `pip install black=={version}`, or else tell Spotless where it is with `black().pathToExe('path/to/executable')`")
	.fixWrongVersion("Try running `pip install --force-reinstall black=={version}`, or else specify `black('{versionFound}')` to Spotless")

It would be nice if we could handle this better, or at least have better instructions. There are a few python plugins in the gradle ecosystem, I'll reach out to them to see if they are interested.

[japoorv]

When this is run on linux the black --version gives output

black, 22.6.0 (compiled: yes)
Python (CPython) 3.9.6

This doesn't parse with the regex version (\S*) .
We should ideally have a way to enforce this regex as well, since different executable version can have different way of showing versions too.

I see this has already been fixed, sorry for the confusion

[leicmi]

One way to "bundle" black would be to bootstrap a python-environment with black using gradle-python-envs from JetBrains:
build.gradle:

plugins{
    id "com.jetbrains.python.envs" version "0.0.31"
}
envs {
    bootstrapDirectory = new File(buildDir, 'bootstrap')
    envsDirectory = file(buildDir)
    condaenv "py_env", "3.10", [condaPackage("black")]
}
task show_black_version(type: Exec, dependsOn: 'build_envs'){
    commandLine("./build/py_env/bin/black", "--version")
}

However, this always bootstraps MiniConda and the environment, independent of whether another python installation with black already exists.
What do you think about such an approach?

[nedtwigg]

This would work for the Gradle plugin, but not the Maven one, and that's fine with me! One way to incorporate something like this would be to add documentation to the manual on how to glue the two plugins together: https://github.com/diffplug/spotless/tree/main/plugin-gradle#black

and then do black().pathToExe('./build/py_env/bin/black')

[leicmi]

Unfortunately, it seems like this approach won't work.
I tried to set a dependency on the python-environment using spotlessPythonApply.dependsOn('build_envs') (in build.gradle), however as of now ForeignExe.confirmVersionAndGetAbsolutePath() (of spotless) seems to be executed before any Gradle tasks.

[nedtwigg]

Ahh, yes. confirmVersionAndGetAbsolutePath is called as part of up-to-date checking... I really hope the Gradle depenency model learns to play nice with PyPI/NPM/RubyGems/etc someday...

[nedtwigg]

@ibabel-chwy if you have a specific problem you should open a new issue and include the requested info (version, logs, etc)