Separate custom matchers declarations into .d.ts file

__tests__/EventLogger.test.ts

@@ -9,6 +9,9 @@ import type {
 } from '../src/typings/EventLogs';
 import { StatesRuntimeError } from '../src/error/predefined/StatesRuntimeError';
 import { EventLogger } from '../src/stateMachine/EventLogger';
+
+// NOTE: We need to import the custom matcher declarations, since VSCode doesn't recognize custom tsconfigs
+// See: https://github.com/microsoft/vscode/issues/12463
 import './_customMatchers';
 
 afterEach(() => {

__tests__/_customMatchers.d.ts

@@ -0,0 +1,15 @@
+/* eslint-disable @typescript-eslint/no-empty-interface */
+export {};
+
+interface CustomMatchers<R = unknown> {
+  toSettle(ms: number): Promise<R>;
+  numberBetween(argumentOne: number, argumentTwo: number): R;
+}
+
+declare global {
+  namespace jest {
+    interface Expect extends CustomMatchers {}
+    interface Matchers<R> extends CustomMatchers<R> {}
+    interface InverseAsymmetricMatchers extends CustomMatchers {}
+  }
+}

__tests__/tsconfig.json

@@ -0,0 +1,8 @@
+{
+  "extends": "../tsconfig.json",
+  "compilerOptions": {
+    "skipLibCheck": false,
+    "noEmit": true
+  },
+  "files": ["_customMatchers.d.ts"]
+}

jest.config.cjs

@@ -1,7 +1,21 @@
+/* eslint-disable @typescript-eslint/no-var-requires */
+
+const { defaults: tsjPreset } = require('ts-jest/presets');
+
 /** @type {import('ts-jest').JestConfigWithTsJest} */
 module.exports = {
-  preset: 'ts-jest',
   testEnvironment: 'node',
   testMatch: ['**/__tests__/**/*.test.ts'],
+  setupFilesAfterEnv: ['./__tests__/customMatchers.ts'],
+  moduleFileExtensions: ['js', 'mjs', 'cjs', 'ts', 'd.ts', 'json'],
   verbose: true,
+  transform: {
+    '^.+\\.ts$': [
+      'ts-jest',
+      {
+        ...tsjPreset.transform,
+        tsconfig: './__tests__/tsconfig.json',
+      },
+    ],
+  },
 };