Rule Proposal: Enforce JSX Presence in `.tsx` Files (`no-tsx-without-jsx`)

Description:

I would like to propose a new rule for eslint-plugin-react that enforces the presence of JSX elements in files with a .tsx extension. This rule would help maintain consistency and clarity in TypeScript projects using React or other JSX-based libraries.

Problem Statement:

Currently, it’s possible to create .tsx files without any JSX elements. This can lead to:

• Confusion: Developers might use the .tsx extension unnecessarily for files that do not contain any JSX, potentially causing confusion about the file's intended purpose.
• Consistency Issues: Keeping .ts and .tsx file distinctions clear ensures that the purpose of each file is easily understood by other developers working on the project.

Proposed Rule: no-tsx-without-jsx

• This rule would throw an error if a file with the .tsx extension does not contain any JSX elements.
• The rule would suggest renaming the file to a .ts extension if JSX is not present.

Example Use Cases:

• Valid (Contains JSX):

  // myComponent.tsx
  import React from 'react';
  
  const MyComponent = () => <div>Hello, World!</div>;
  
  export default MyComponent;
  

• Invalid (No JSX, should be .ts):

  // utilityFunction.tsx
  export function utilityFunction() {
      return 42;
  }
  

Benefits:

• Improves Code Clarity: By ensuring that .tsx files contain JSX, the codebase remains easier to navigate and understand.
• Encourages Best Practices: This rule will encourage developers to use .tsx only when necessary, and .ts otherwise, maintaining clearer file distinctions.
• Aligns with TypeScript-First Principles: This rule fits well within a TypeScript-specific plugin, helping developers make the best use of TypeScript’s features and extensions.

Similar Rules and Why This Is Unique:

• The react/jsx-filename-extension rule in eslint-plugin-react allows configuring when JSX is allowed in certain extensions but does not specifically target .tsx files and their usage within TypeScript projects.

Additional Context:

I have developed a prototype version of this rule in a custom ESLint plugin. You can check that at https://github.com/HesamSe/eslint-plugin-recommended/blob/main/src/rules/noTsxWithoutJsx.ts