feat: support markdown_text parameter

[WilliamBergamin]

Summary

#1713 reports that warnings are printed when the markdown_text parameter is passed without the text parameter, but passing text alongside markdown_text results in an API error markdown_text_conflict 😢 . This behavior affects chat_postMessage, chat_update, chat_scheduledMessage and chat_postEphemeral methods.

This PR aims to add support for the markdown_text parameter by omitting warnings when markdown_text is passed without text

Testing

Use the following app to test the functionality

import os
import logging

from slack_sdk import WebClient

logging.basicConfig(level=logging.INFO)

client = WebClient(token=os.environ.get("SLACK_BOT_TOKEN"))

markdown_content = (
    "*Welcome to Our Bolt Python Project!* :rocket:\n\n"
    ">This is a Slack app built with Bolt for Python.\n\n"
    "*Key features:*\n"
    "• Message handling\n"
    "• Event subscriptions\n"
    "• Interactive components\n"
    "• App Home customization\n\n"
    "```python\n"
    "# Quick setup\n"
    "python3 -m venv .venv\n"
    "source .venv/bin/activate\n"
    "pip install -r requirements.txt\n"
    "```\n\n"
    "Check out <https://api.slack.com/start/building/bolt-python|Bolt documentation> for more details."
)

response = client.chat_postMessage(
    channel="C111",
    text="hello",
    markdown_text=markdown_content
)

if response["ok"]:
    client.logger.info(f"Message posted successfully")
    client.logger.info(f"Channel: {response['channel']}")
    client.logger.info(f"Timestamp: {response['ts']}")
    client.logger.info(f"Message: {response['message']['text'][:50]}...")
else:
    client.logger.error(f"Error posting message: {response['error']}")
    client.logger.error(f"Full response: {response}")

1. Including just the text argument should post a message as expected 🟢
2. Including just the markdown_text argument should post a message as expected 🟢 no warnings
3. Including the markdown_text and text arguments results in an API error markdown_text_conflict
4. Excluding both arguments results in an API error no_text

Feedback

I've added the markdown_text argument in the methods definitions, but we could omit this since developers are able to pass this value through keyword arguments, should we explicitly define this argument?

Category

• slack_sdk.web.WebClient (sync/async) (Web API client)
• slack_sdk.webhook.WebhookClient (sync/async) (Incoming Webhook, response_url sender)
• slack_sdk.socket_mode (Socket Mode client)
• slack_sdk.signature (Request Signature Verifier)
• slack_sdk.oauth (OAuth Flow Utilities)
• slack_sdk.models (UI component builders)
• slack_sdk.scim (SCIM API client)
• slack_sdk.audit_logs (Audit Logs API client)
• slack_sdk.rtm_v2 (RTM client)
• /docs (Documents)
• /tutorial (PythOnBoardingBot tutorial)
• tests/integration_tests (Automated tests for this library)

Requirements

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.
• I've run python3 -m venv .venv && source .venv/bin/activate && ./scripts/run_validation.sh after making the changes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.91%. Comparing base (8922dc8) to head (4fb424a).
⚠️ Report is 2 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1718      +/-   ##
==========================================
+ Coverage   84.90%   84.91%   +0.01%     
==========================================
  Files         113      113              
  Lines       12892    12895       +3     
==========================================
+ Hits        10946    10950       +4     
+ Misses       1946     1945       -1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[ewanek1]

LGTM! 🙌 ☺

[zimeg]

@WilliamBergamin LGTM! And thanks for keeping outputs relevant with these markdown formats 🎁

I left a few comments below but like where this PR moves things as is 👾

[zimeg]

I've added the markdown_text argument in the methods definitions, but we could omit this since developers are able to pass this value through keyword arguments, should we explicitly define this argument?

praise: Adding this I think is a nice improvement for the typeahead hints found in some editors with virtual environments!

thought: It's nice to know that missing arguments aren't blocking new features though 🤖 ✨

[zimeg]

suggestion(non-blocking): Separating these cases as separate if statements and returns might make later additions more clear 👁️‍🗨️

[WilliamBergamin]

Yess I agree let me see how this looks 💯

[zimeg]

🪄 ✨

[zimeg]

question(non-blocking): Do we want to keep the issue_### pattern or can we change this to something like:

tests/web/test_web_client_warnings.py

[WilliamBergamin]

Good point let me rename this 💯

[zimeg]

🧪 ✨ Awesome changes more with the testing updates and additions! Please do feel free to merge when the time is right.