test env.ts

__test__/config/env.test.ts

@@ -0,0 +1,41 @@
+/* eslint-disable @typescript-eslint/no-var-requires */
+describe("env", () => {
+  describe("schema", () => {
+    it("should validate the schema successfully", () => {
+      expect.assertions(1);
+      expect(() => {
+        import("../../src/config/env");
+      }).not.toThrowError();
+    });
+  });
+
+  describe("environment variables", () => {
+    const DEFAULT_ENV = process.env;
+
+    beforeEach(() => {
+      jest.resetModules();
+      process.env = { ...DEFAULT_ENV };
+    });
+
+    afterAll(() => {
+      process.env = DEFAULT_ENV;
+    });
+
+    it("should throw an error if required environment variables are missing", () => {
+      expect.assertions(1);
+      delete process.env.MONGODB_HOST;
+      const expectedErrorMessage =
+        'Config validation error: "MONGODB_HOST" is required';
+      expect(() => {
+        require("../../src/config/env");
+      }).toThrowError(expectedErrorMessage);
+    });
+
+    it("should configure MONGODB_URL", () => {
+      expect.assertions(1);
+      process.env.MONGODB_NAME = "db";
+      const { env } = require("../../src/config/env");
+      expect(env.MONGODB_URL).toEqual("mongodb://root:pass@localhost:27017/db");
+    });
+  });
+});

package.json

@@ -7,7 +7,7 @@
     "build": "npx tsc",
     "start": "node dist/index.js",
     "dev": "env-cmd nodemon ./src/index.ts",
-    "test": "env-cmd jest",
+    "test": "env-cmd jest --coverage",
     "prettier": "npx prettier --write .",
     "lint": "npx eslint ."
   },

src/config/env.ts

@@ -14,21 +14,21 @@ const schema = Joi.object()
   })
   .unknown();
 
-const { value: env, error } = schema
+const { value, error } = schema
   .prefs({ errors: { label: "key" } })
   .validate(process.env);
 
 if (error != null) {
   throw new Error(`Config validation error: ${error.message}`);
 }
 
-const MONGODB_URL = `mongodb://${env.MONGODB_USER}:${env.MONGODB_PASS}@${
-  env.MONGODB_HOST
-}:${env.MONGODB_PORT}/${
-  env.MONGODB_NAME !== undefined ? env.MONGODB_NAME : ""
+const MONGODB_URL = `mongodb://${value.MONGODB_USER}:${value.MONGODB_PASS}@${
+  value.MONGODB_HOST
+}:${value.MONGODB_PORT}/${
+  value.MONGODB_NAME !== undefined ? value.MONGODB_NAME : ""
 }`;
 
-export default {
-  ...env,
+export const env = {
+  ...value,
   MONGODB_URL,
 };

src/config/index.ts

@@ -1,3 +1,3 @@
-import env from "./env";
+import { env } from "./env";
 
 export { env };