Add working test config for filesystem

src/filesystem/jest.config.cjs

@@ -0,0 +1,23 @@
+/** @type {import('ts-jest').JestConfigWithTsJest} */
+module.exports = {
+  preset: 'ts-jest',
+  testEnvironment: 'node',
+  extensionsToTreatAsEsm: ['.ts'],
+  moduleNameMapper: {
+    '^(\\.{1,2}/.*)\\.js$': '$1',
+  },
+  transform: {
+    '^.+\\.tsx?$': [
+      'ts-jest',
+      {
+        useESM: true,
+      },
+    ],
+  },
+  testMatch: ['**/__tests__/**/*.test.ts'],
+  collectCoverageFrom: [
+    '**/*.ts',
+    '!**/__tests__/**',
+    '!**/dist/**',
+  ],
+}