TypeScript Breaking Change Detector

Overview

The TypeScript Breaking Change Detector is a tool designed for TypeScript developers to identify breaking changes when updating APIs or type declarations. By comparing the structure and types in the previous and current versions of TypeScript codebases, it highlights potential compatibility issues.

The tool performs AST-based analysis to validate changes and reports when updates might break backward compatibility for users of the code.

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Features

What This Tool Does

• Analyzes changes in TypeScript declarations such as:
  • Classes, interfaces, enums, variables, functions, and type aliases.
• Detects breaking changes, including:
  • Removed or renamed exports.
  • Changes in function signatures or return types.
  • Incompatible modifications to types or type annotations.

Examples of Errors Detected

Here are some common breaking changes that the tool identifies:

1. Export Removed

// Previous version
export interface User {
  name: string;
  age: number;
}

// Current version
interface User {
  name: string;
  age: number;
}

Error: EXPORT_REMOVED - interface User

2. Property Type Changed

// Previous version
export interface User {
  name: string;
}

// Current version
export interface User {
  name: number;
}

Error: PROPERTY_CHANGED - property name: string in interface User

3. Function Parameter Changed

// Previous version
export function calculate(a: number, b: number): number;

// Current version
export function calculate(a: number): number;

Error: FUNCTION_PARAMETER_CHANGED - function calculate(a: number, b: number): number

4. Enum Member Removed

// Previous version
export enum Colors {
  Red,
  Blue,
}

// Current version
export enum Colors {
  Red,
}

Error: ENUM_MEMBERS_CHANGED - look at members of Colors

5. Variable Type Changed

// Previous version
export let counter: number;

// Current version
export let counter: string;

Error: VARIABLE_CHANGED_OR_REMOVED - variable counter: number

How It Works

AST Comparison:

Parses the TypeScript code into an Abstract Syntax Tree (AST). Analyzes the structure of declarations in the previous and current versions.

Validation:

Compares nodes in the AST to detect changes in type annotations, member definitions, and function signatures.

Error Reporting:

Generates clear error messages for detected breaking changes, helping developers address issues quickly.

Future Plans

Detailed Reporting:

Provide more context in error messages, such as locations and suggestions.

CLI Tool:

Run the detector via a command-line interface.

Contributing

Contributions are welcome! Feel free to fork the repository, suggest improvements, or add new features.

License This project is licensed under the MIT License.