bug: color is missing if I print a diff with rich.syntax

[15r10nk]

Description of the bug

I use markdown-exec to include the output of pytest in my documentation.
I use rich to generate some diffs during this run and have the problem that the red and green colors are missing in the diff.

I was able to reproduce this bug without pytest, but I have no idea if this is a markdown-exec or rich problem.

Can you please look into?

To Reproduce

see the repository

pip install -r requirements.txt
mkdocs serve

Expected behavior

I would expect that markdown-exec is able to produce the same colors which I also see in the terminal.

Environment information

python -m markdown_exec.debug  # | xclip -selection clipboard

• System: Linux-6.1.0-18-amd64-x86_64-with-glibc2.36
• Python: cpython 3.12.1
• Environment variables:
• Installed packages:
  • markdown-exec v1.8.0

Additional context

[pawamoy]

Hey @15r10nk, thanks for the report!

Interesting. My first intuition is that Rich uses ANSI codes that are not supported by pygments-ansi. I'll replicate the issue locally and report back 🙂

[pawamoy]

Unfortunately none of the available color systems improve the situation 😕 I really thought the standard one would help.

I don't know Rich enough to understand what it does with ANSI codes. I think its Syntax objects are a bit more clever and use more than just the 16 color variations. Rich also sets a background for the diff block, that might be what is causing issues here, as background+foreground can be combined in a single ANSI sequence that maybe pygments-ansi or its style sheet have trouble with.

Workaround:

# codi.py

import os
from rich.console import Console
from rich.syntax import Syntax

console=Console(color_system="256")

code = """
  code
- a
+ b
"""

with open(os.devnull, "w") as devnull:
    console = Console(record=True, width=65, file=devnull, markup=False)
    renderable = Syntax(code, "diff", theme="material")
    console.print(renderable, markup=True, highlight=False)
print(console.export_html(inline_styles=True, code_format="<pre><code>{code}</code></pre>"))

<!-- index.md -->
```python exec="1" html="1"
--8<-- "codi.py"
```

[pawamoy]

Here's the ANSI output of Rich with 256 color mode:

\e[31m red\e[0m
\e[32m green\e[0m
\e[48;5;235m                                                                   \e[0m
\e[38;5;231;48;5;235m \e[0m\e[38;5;231;48;5;235m code\e[0m\e[48;5;235m                                                             \e[0m
\e[38;5;204;48;5;235m- a\e[0m\e[48;5;235m                                                                \e[0m
\e[38;5;148;48;5;235m+ b\e[0m\e[48;5;235m                                                                \e[0m
\e[48;5;235m                                                                   \e[0m

I've manually escaped the escape sequence (\e) and removed some whitespace.

[pawamoy]

Here it is with the standard color mode:

\e[31m red\e[0m
\e[32m green\e[0m
\e[40m                                      \e[0m
\e[97;40m \e[0m\e[97;40m code\e[0m\e[40m                                \e[0m
\e[91;40m- a\e[0m\e[40m                                   \e[0m
\e[92;40m+ b\e[0m\e[40m                                   \e[0m
\e[40m                                      \e[0m

[pawamoy]

It's a bit better with this (works for b but not for a for some reason):

console = Console(color_system="standard")
code = """
  code
- a
+ b
"""
console.print(Syntax(code, "diff", theme="ansi_light"))

[pawamoy]

Aha! This translates as a -Color-BrightRed CSS class but there's no such class in the style sheet, only -Color-Bold-Red. Let me try to update the style sheet 😄

[pawamoy]

Should be fixed in v1.8.1. Try with the standard color system and the ansi_light/ansi_dark theme and let me know if there are any other issues 🙂

[15r10nk]

Thank you, it works for me now.