This week in #dev (Jan 9, 2026)

Welcome to another edition of This Week in #dev, a series of posts where we bring some of our most interesting Slack conversations to the public.

Overriding Rails Credentials with Environment Variables

Rob Whittaker shares an article that demonstrates how you can override Rails credentials with environment variables using the Rails 8.2 Rails.app.creds accessor. This can be useful for building a feature flag system:

features:
  dark_mode: false

To enable dark mode, use:

FEATURES__DARK_MODE=1 ./bin/rails server

The Rails image_submit_tag helper

Matheus Richard learned about Rails’ image_submit_tag, a helper that displays an image which when clicked will submit the form.

image_submit_tag("login.png")
# => <input src="/assets/login.png" type="image" />

Counting Tests with RSpec’s --dry-run Option

Justin Toniazzo shares a tip about using rspec --dry-run to list all tests without executing them. This can be useful for quickly determining the number of tests in a codebase:

bin/rspec --dry-run --format json | jq '.examples | length'

Thanks

This edition was brought to you by Justin Toniazzo, Matheus Richard, and Rob Whittaker. Thanks to all contributors! 🎉

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