[Fix] import/no-cycle: fix perf regression

Fixes import-js#1943.

Author: mblaszczyk-atlassian

src/ExportMap.js

@@ -22,6 +22,7 @@ let parseConfigFileTextToJson;
 const log = debug('eslint-plugin-import:ExportMap');
 
 const exportCache = new Map();
+const tsConfigCache = new Map();
 
 export default class ExportMap {
   constructor(path) {
@@ -438,9 +439,11 @@ ExportMap.parse = function (path, content, context) {
 
   const source = makeSourceCode(content, ast);
 
-  function isEsModuleInterop() {
+  function readTsConfig() {
     const tsConfigInfo = tsConfigLoader({
-      cwd: context.parserOptions && context.parserOptions.tsconfigRootDir || process.cwd(),
+      cwd:
+        (context.parserOptions && context.parserOptions.tsconfigRootDir) ||
+        process.cwd(),
       getEnv: (key) => process.env[key],
     });
     try {
@@ -450,12 +453,26 @@ ExportMap.parse = function (path, content, context) {
           // this is because projects not using TypeScript won't have typescript installed
           ({ parseConfigFileTextToJson } = require('typescript'));
         }
-        const tsConfig = parseConfigFileTextToJson(tsConfigInfo.tsConfigPath, jsonText).config;
-        return tsConfig.compilerOptions.esModuleInterop;
+        return parseConfigFileTextToJson(tsConfigInfo.tsConfigPath, jsonText).config;
       }
     } catch (e) {
-      return false;
+      // Catch any errors
     }
+
+    return null;
+  }
+
+  function isEsModuleInterop() {
+    const cacheKey = hashObject({
+      tsconfigRootDir: context.parserOptions && context.parserOptions.tsconfigRootDir,
+    }).digest('hex');
+    let tsConfig = tsConfigCache.get(cacheKey);
+    if (typeof tsConfig === 'undefined') {
+      tsConfig = readTsConfig();
+      tsConfigCache.set(cacheKey, tsConfig);
+    }
+
+    return tsConfig !== null ? tsConfig.compilerOptions.esModuleInterop : false;
   }
 
   ast.body.forEach(function (n) {

tests/files/typescript-export-assign-property.ts

@@ -0,0 +1,3 @@
+const AnalyticsNode = { Analytics: {} };
+
+export = AnalyticsNode.Analytics;

tests/src/core/getExports.js

@@ -1,6 +1,8 @@
 import { expect } from  'chai';
 import semver from 'semver';
+import sinon from 'sinon';
 import eslintPkg from 'eslint/package.json';
+import * as tsConfigLoader from 'tsconfig-paths/lib/tsconfig-loader';
 import ExportMap from '../../../src/ExportMap';
 
 import * as fs from 'fs';
@@ -49,9 +51,9 @@ describe('ExportMap', function () {
     expect(firstAccess).to.exist;
 
     const differentSettings = Object.assign(
-      {},
       fakeContext,
-      { parserPath: 'espree' });
+      { parserPath: 'espree' },
+    );
 
     expect(ExportMap.get('./named-exports', differentSettings))
       .to.exist.and
@@ -358,8 +360,12 @@ describe('ExportMap', function () {
         let imports;
         before('load imports', function () {
           this.timeout(20000);  // takes a long time :shrug:
+          sinon.spy(tsConfigLoader, 'tsConfigLoader');
           imports = ExportMap.get('./typescript.ts', context);
         });
+        after('clear spies', function () {
+          tsConfigLoader.tsConfigLoader.restore();
+        });
 
         it('returns something for a TypeScript file', function () {
           expect(imports).to.exist;
@@ -388,9 +394,36 @@ describe('ExportMap', function () {
         it('has exported abstract class', function () {
           expect(imports.has('Bar')).to.be.true;
         });
+
+        it('should cache tsconfig until tsconfigRootDir parser option changes', function () {
+          const customContext = Object.assign(
+            context,
+            {
+              parserOptions: {
+                tsconfigRootDir: null,
+              },
+            },
+          );
+          expect(tsConfigLoader.tsConfigLoader.callCount).to.equal(0);
+          ExportMap.parse('./baz.ts', 'export const baz = 5', customContext);
+          expect(tsConfigLoader.tsConfigLoader.callCount).to.equal(1);
+          ExportMap.parse('./baz.ts', 'export const baz = 5', customContext);
+          expect(tsConfigLoader.tsConfigLoader.callCount).to.equal(1);
+
+          const differentContext = Object.assign(
+            context,
+            {
+              parserOptions: {
+                tsconfigRootDir: process.cwd(),
+              },
+            },
+          );
+
+          ExportMap.parse('./baz.ts', 'export const baz = 5', differentContext);
+          expect(tsConfigLoader.tsConfigLoader.callCount).to.equal(2);
+        });
       });
     });
-
   });
 
   // todo: move to utils