fix(core): support comments in tsconfig.json

Closes #730

packages/core/package.json

@@ -55,6 +55,7 @@
     "fs-extra": "^9.0.1",
     "globby": "^11.0.1",
     "reflect-metadata": "^0.1.13",
+    "strip-json-comments": "^3.1.1",
     "uuid": "^8.1.0"
   },
   "peerDependencies": {

packages/core/src/utils/ConfigurationLoader.ts

@@ -1,5 +1,6 @@
-import { pathExists } from 'fs-extra';
-import path from 'path';
+import { pathExists, readFile } from 'fs-extra';
+import { join, isAbsolute } from 'path';
+import stripJsonComments from 'strip-json-comments';
 import { IDatabaseDriver } from '../drivers';
 import { Configuration } from './Configuration';
 import { Utils } from './Utils';
@@ -56,17 +57,16 @@ export class ConfigurationLoader {
     return paths;
   }
 
-  static async registerTsNode(configPath = 'tsconfig.json') {
-    const tsConfigPath = path.join(process.cwd(), configPath);
+  static async registerTsNode(configPath = 'tsconfig.json'): Promise<void> {
+    const tsConfigPath = isAbsolute(configPath) ? configPath : join(process.cwd(), configPath);
 
     Utils.requireFrom('ts-node', tsConfigPath).register({
       project: tsConfigPath,
       transpileOnly: true,
     });
 
     if (await pathExists(tsConfigPath)) {
-      // eslint-disable-next-line @typescript-eslint/no-var-requires
-      const tsConfig = require(tsConfigPath);
+      const tsConfig = await this.getTsConfig(tsConfigPath);
       /* istanbul ignore next */
       const paths = tsConfig.compilerOptions?.paths;
 
@@ -79,6 +79,11 @@ export class ConfigurationLoader {
     }
   }
 
+  static async getTsConfig(tsConfigPath: string): Promise<Dictionary> {
+    const json = await readFile(tsConfigPath);
+    return JSON.parse(stripJsonComments(json.toString()));
+  }
+
 }
 
 export interface Settings {

tests/cli/CLIHelper.test.ts

@@ -88,6 +88,13 @@ describe('CLIHelper', () => {
     await expect(CLIHelper.getConfiguration()).rejects.toThrowError(`MikroORM config file not found in ['./mikro-orm.config.js']`);
   });
 
+  test('registerTsNode works with tsconfig.json with comments', async () => {
+    const requireFromMock = jest.spyOn(Utils, 'requireFrom');
+    requireFromMock.mockImplementation(() => ({ register: jest.fn() }));
+    await expect(ConfigurationLoader.registerTsNode(__dirname + '/../tsconfig.json')).resolves.toBeUndefined();
+    await expect(ConfigurationLoader.registerTsNode('./tests/tsconfig.json')).resolves.toBeUndefined();
+  });
+
   test('gets ORM configuration [no package.json]', async () => {
     const pathExistsMock = jest.spyOn(require('fs-extra'), 'pathExists');
     pathExistsMock.mockImplementation(async path => (path as string).endsWith('mikro-orm.config.js'));

tests/tsconfig.json

@@ -1,4 +1,4 @@
 {
-  "extends": "../tsconfig.json",
+  "extends": "../tsconfig.json", /* omg */
   "include": ["**/*", "../packages/*/src/**/*"]
 }