prefer-each.ts

import type { TSESTree } from '@typescript-eslint/utils';
import { type JestFnType, createRule, parseJestFnCall } from './utils';

export default createRule({
  name: __filename,
  meta: {
    docs: {
      description: 'Prefer using `.each` rather than manual loops',
    },
    messages: {
      preferEach: 'prefer using `{{ fn }}.each` rather than a manual loop',
    },
    type: 'suggestion',
    schema: [],
  },
  defaultOptions: [],
  create(context) {
    const jestFnCalls: JestFnType[] = [];
    let inTestCaseCall = false;

    const recommendFn = () => {
      if (jestFnCalls.length === 1 && jestFnCalls[0] === 'test') {
        return 'it';
      }

      return 'describe';
    };

    const enterForLoop = () => {
      if (jestFnCalls.length === 0 || inTestCaseCall) {
        return;
      }

      jestFnCalls.length = 0;
    };
    const exitForLoop = (
      node:
        | TSESTree.ForInStatement
        | TSESTree.ForOfStatement
        | TSESTree.ForStatement,
    ) => {
      if (jestFnCalls.length === 0 || inTestCaseCall) {
        return;
      }

      context.report({
        node,
        messageId: 'preferEach',
        data: { fn: recommendFn() },
      });

      jestFnCalls.length = 0;
    };

    return {
      ForStatement: enterForLoop,
      'ForStatement:exit': exitForLoop,
      ForInStatement: enterForLoop,
      'ForInStatement:exit': exitForLoop,
      ForOfStatement: enterForLoop,
      'ForOfStatement:exit': exitForLoop,
      CallExpression(node) {
        const { type: jestFnCallType } = parseJestFnCall(node, context) ?? {};

        if (
          jestFnCallType === 'hook' ||
          jestFnCallType === 'describe' ||
          jestFnCallType === 'test'
        ) {
          jestFnCalls.push(jestFnCallType);
        }

        if (jestFnCallType === 'test') {
          inTestCaseCall = true;
        }
      },
      'CallExpression:exit'(node) {
        const { type: jestFnCallType } = parseJestFnCall(node, context) ?? {};

        if (jestFnCallType === 'test') {
          inTestCaseCall = false;
        }
      },
    };
  },
});