[Fix] default, ExportMap: Resolve extended TypeScript configuration files

Fixes #1908.

Author: mrmckeb

Diff for: CHANGELOG.md

@@ -15,6 +15,7 @@ This change log adheres to standards from [Keep a CHANGELOG](http://keepachangel
 ### Fixed
 - [`no-unresolved`]: ignore type-only imports ([#2220], thanks [@jablko])
 - [`order`]: fix sorting imports inside TypeScript module declarations ([#2226], thanks [@remcohaszing])
+- [`default`], `ExportMap`: Resolve extended TypeScript configuration files ([#2240], thanks [@mrmckeb])
 
 ### Changed
 - [Refactor] switch to an internal replacement for `pkg-up` and `read-pkg-up` ([#2047], thanks [@mgwalker])
@@ -915,6 +916,7 @@ for info on changes for earlier releases.
 
 [`memo-parser`]: ./memo-parser/README.md
 
+[#2240]: https://github.com/import-js/eslint-plugin-import/pull/2240
 [#2233]: https://github.com/import-js/eslint-plugin-import/pull/2233
 [#2226]: https://github.com/import-js/eslint-plugin-import/pull/2226
 [#2220]: https://github.com/import-js/eslint-plugin-import/pull/2220
@@ -1509,6 +1511,7 @@ for info on changes for earlier releases.
 [@mgwalker]: https://github.com/mgwalker
 [@MikeyBeLike]: https://github.com/MikeyBeLike
 [@mplewis]: https://github.com/mplewis
+[@mrmckeb]: https://github.com/mrmckeb
 [@nickofthyme]: https://github.com/nickofthyme
 [@nicolashenry]: https://github.com/nicolashenry
 [@noelebrun]: https://github.com/noelebrun

Diff for: src/ExportMap.js

@@ -1,4 +1,5 @@
 import fs from 'fs';
+import { dirname } from 'path';
 
 import doctrine from 'doctrine';
 
@@ -18,7 +19,7 @@ import { tsConfigLoader } from 'tsconfig-paths/lib/tsconfig-loader';
 
 import includes from 'array-includes';
 
-let parseConfigFileTextToJson;
+let ts;
 
 const log = debug('eslint-plugin-import:ExportMap');
 
@@ -525,12 +526,15 @@ ExportMap.parse = function (path, content, context) {
     });
     try {
       if (tsConfigInfo.tsConfigPath !== undefined) {
-        const jsonText = fs.readFileSync(tsConfigInfo.tsConfigPath).toString();
-        if (!parseConfigFileTextToJson) {
-          // this is because projects not using TypeScript won't have typescript installed
-          ({ parseConfigFileTextToJson } = require('typescript'));
-        }
-        return parseConfigFileTextToJson(tsConfigInfo.tsConfigPath, jsonText).config;
+        // Projects not using TypeScript won't have `typescript` installed.
+        if (!ts) { ts = require('typescript'); }
+  
+        const configFile = ts.readConfigFile(tsConfigInfo.tsConfigPath, ts.sys.readFile);
+        return ts.parseJsonConfigFileContent(
+          configFile.config,
+          ts.sys,
+          dirname(tsConfigInfo.tsConfigPath),
+        );
       }
     } catch (e) {
       // Catch any errors
@@ -545,11 +549,11 @@ ExportMap.parse = function (path, content, context) {
     }).digest('hex');
     let tsConfig = tsConfigCache.get(cacheKey);
     if (typeof tsConfig === 'undefined') {
-      tsConfig = readTsConfig();
+      tsConfig = readTsConfig(context);
       tsConfigCache.set(cacheKey, tsConfig);
     }
 
-    return tsConfig && tsConfig.compilerOptions ? tsConfig.compilerOptions.esModuleInterop : false;
+    return tsConfig && tsConfig.options ? tsConfig.options.esModuleInterop : false;
   }
 
   ast.body.forEach(function (n) {

Diff for: tests/files/typescript-extended-config/index.d.ts

@@ -0,0 +1,3 @@
+export = FooBar;
+
+declare namespace FooBar {}

Diff for: tests/files/typescript-extended-config/tsconfig.base.json

@@ -0,0 +1,5 @@
+{
+  "compilerOptions": {
+    "esModuleInterop": true
+  }
+}

Diff for: tests/files/typescript-extended-config/tsconfig.json

@@ -0,0 +1,4 @@
+{
+  "extends": "./tsconfig.base.json",
+  "compilerOptions": {}
+}

Diff for: tests/src/rules/default.js

@@ -231,6 +231,17 @@ context('TypeScript', function () {
             tsconfigRootDir: path.resolve(__dirname, '../../files/typescript-export-react-test-renderer/'),
           },
         }),
+        test({
+          code: `import Foo from "./typescript-extended-config"`,
+          parser,
+          settings: {
+            'import/parsers': { [parser]: ['.ts'] },
+            'import/resolver': { 'eslint-import-resolver-typescript': true },
+          },
+          parserOptions: {
+            tsconfigRootDir: path.resolve(__dirname, '../../files/typescript-extended-config/'),
+          },
+        }),
         test({
           code: `import foobar from "./typescript-export-assign-property"`,
           parser,