Flow Type Transformation Utility

Create a Node.js command-line utility that transforms Flow-typed JavaScript files in a directory, with support for filtering files using ignore patterns.

Requirements

Build a CLI tool that wraps the type removal functionality and adds custom path filtering logic.

Command-Line Interface

The utility should accept the following arguments:

• <source-dir>: Source directory containing Flow-typed files
• <output-dir>: Destination directory for transformed files
• --ignore <pattern>: Optional regex pattern to exclude files (e.g., "test|spec")

Path Filtering Logic

• Read all .js files from the source directory recursively
• Apply the ignore pattern to filter out unwanted files
• Transform only files that pass the filter
• Preserve directory structure in the output

File Transformation

• Use the type removal API to transform each file
• Write transformed files to the output directory with the same relative paths
• Create necessary subdirectories as needed
• Report the number of files processed and skipped

Test Cases

• Given a source directory with files src/app.js, src/test/app.test.js, and src/utils.js, using --ignore "test" transforms only src/app.js and src/utils.js @test
• Processing multiple files preserves the directory structure in the output directory @test
• Files are correctly transformed with type annotations removed @test

Implementation

@generates

Dependencies { .dependencies }

flow-remove-types { .dependency }

Provides Flow type annotation removal functionality.