Use local font in test suite

[ehmatthes]

Tests are brittle due to cross-platform font issues. Running tests using an embedded open font would address this once and for all, and allow a low, reliable test pixel ratio.

• Add a font file to the test resources.
• Modify git-sim to support fonts with paths.
• Verify that generated images are using the installed font.
• Update reference files.
• Verify that tests pass on all current contributors' systems.
• Add a test for a named font, because most tests will use a path to a font.

[ehmatthes]

Working notes

• Path to font is being converted from --font=/Users/eric/projects/git-sim/tests/e2e_tests/ProggyClean.ttf to PosixPath('/Users/eric/projects/Users/eric/projects/git-sim/.venv/bin/git-sim/tests/e2e_tests/ProggyClean.ttf'). Fix this. (Fixed; this was my issue in get_cmd_parts().

There is overlap between how git-sim uses font and how Manim uses font. If font is a path, we'd need to use that in a call to m.register_font(). But settings.font is used throughout git-sim in ways that are incompatible with a path to a font file.

The quick patchy demo fix for getting git-sim log to work with a path at the --font arg is to separate out the path and font variables:

    def construct(self):
        from pathlib import Path
        font_path = Path(settings.font)
        if font_path.exists():
            with m.register_font(font_path):
                if not settings.stdout and not settings.output_only_path and not settings.quiet:
                    print(
                        f"{settings.INFO_STRING} {type(self).__name__.lower()}{' --all' if self.all_subcommand else ''}{' -n ' + str(self.n) if self.n_subcommand else ''}"
                    )
                self.font = "ProggyCleanTT"
                self.show_intro()
                ...

• Trace this back to sort out where we can call m.register_font() so it supports all git-sim commands.
  • Set context and deal with fonts in GitSimBaseCommand.__init__()!
• Remove diagnostics.
• Update all git-sim commands to use font_context.
• Update reference files.
• Questions:
  • Where should font_context live?
  • What font should be bundled? Consider appearance, and license.

[ehmatthes]

Working notes

• This approach requires the fonttools package for end users as well.
• Learn more about context managers. Is there a way to use register_font() without a context manager? Adding another level indentation to more complex commands such as construct() is not very nice.

[ehmatthes]

Rework on fresh branch

The fix_font_tests branch is a messy POC. Restart on a fresh branch.

• Build support for paths in --font.
• Modify tests to use path to local font file.
• Test on Windows.
  • Had to install git-dummy first, then install git-sim. Otherwise git-dummy was not on path?
  • Highest pixel ratio was 0.00532. This is well below the current 0.015, and well below the older 0.0075.
• Sign all commits.
• Push and PR, with notes.

[ehmatthes]

PR Notes

• What is the best place to put get_font_name()? Right now it's in main.py.
• Placing this work in main.py because that's where settings are being processed.
• Do we need to return _handle_animations() in commands.py?
• Is the type for settings.font_context correct?
• Using a font with obvious differences for development work.
• Run pip install fonttools.
• Can pixel ratio be set lower with this approach?
• Mention script to rename test files.

[ehmatthes]

Other notes

• Consider using opencv in compare_images()? It's already a dependency of the project.
• Don't parametrize commands. Repetition is fine in test suites, and we can see the actual raw_cmd.
  • Do consider a helper function that would take raw_cmd and a part of the output filename to validate.

[ehmatthes]

Closing, as the main work here has been merged in git-sim 98. Also, open tasks have been moved to git-sim 99.