Overview

This PR implements the Feature Request to add a --check flag to the format command.

Changes

• Added a new --check flag to the format command
• Modified the format command implementation to support check mode without modifying files
• Enhanced the output formatting to clearly show which files need formatting
• Made the command return exit code 1 if any files need formatting in check mode

How it works

When used with --check, the command:

1. Analyzes each file that would be formatted
2. Compares the current content with what it would be if formatted
3. Reports files needing formatting without modifying them
4. Returns exit code 1 if any files need formatting

Example usage

# Check if all files are formatted correctly without modifying them
dataform format --check

# Check specific files
dataform format --check --actions="definitions/my_model.sqlx" 

Testing

I've tested both the regular format mode (which continues to work as before) and the new check mode.

In check mode:

• When all files are formatted correctly: displays success message and returns exit code 0
• When files need formatting: displays the list of files needing formatting and returns exit code 1

This implementation follows similar patterns used in other code formatting tools like Prettier, ESLint, and Black, making Dataform better suited for modern CI/CD pipelines and development workflows.

Closes #1961