no-decorators-before-export.js

'use strict';

/** @type {import('eslint').Rule.RuleModule} */

function reportInvalidSyntax(context, node) {
  if (isInvalidSyntax(node)) {
    const isDefaultExport = node.type === 'ExportDefaultDeclaration';
    const isNamed = node.declaration.id !== null;
    const name = isNamed ? node.declaration.id.name : '';
    const numDecorators = node.declaration.decorators.length;

    const message = `Usage of class decorator${numDecorators > 1 ? 's' : ''} on the ${
      isNamed ? '' : 'un-named '
    }${isDefaultExport ? 'default ' : ''}export${
      isNamed ? ` ${name}` : ''
    } must occur prior to exporting the class.`;

    if (isNamed) {
      const sourceCode = context.getSourceCode();
      const src = sourceCode.getText(node);
      context.report({
        node,
        message,
        fix(fixer) {
          if (isDefaultExport) {
            let newSrc = src.replace(`export default class ${name}`, `class ${name}`);
            newSrc = `${newSrc}\nexport default ${name};\n`;
            return fixer.replaceText(node, newSrc);
          }
          let newSrc = src.replace(`export class ${name}`, `class ${name}`);
          newSrc = `${newSrc}\nexport { ${name} };\n`;
          return fixer.replaceText(node, newSrc);
        },
      });
    } else {
      context.report({ node, message });
    }
  }
}

function isInvalidSyntax(node) {
  return (
    node.declaration &&
    node.declaration.type === 'ClassDeclaration' &&
    node.declaration.decorators?.length
  );
}

module.exports = {
  meta: {
    type: 'problem',
    docs: {
      description:
        'disallow the use of a class decorator on an export declaration. Enforces use of the decorator on the class directly before exporting the result.',
      category: 'Miscellaneous',
      recommended: true,
      url: 'https://github.com/ember-cli/eslint-plugin-ember/tree/master/docs/rules/no-decorators-before-export.md',
    },
    fixable: 'code',
    schema: [],
  },

  create(context) {
    return {
      ExportDefaultDeclaration(node) {
        return reportInvalidSyntax(context, node);
      },
      ExportNamedDeclaration(node) {
        return reportInvalidSyntax(context, node);
      },
    };
  },
};