♻️ refactor: split into testable modules, add test suite

src/providers/environment.ts

@@ -0,0 +1,39 @@
+import * as path from "path";
+import * as dotenv from "dotenv";
+
+import Logger from "../libs/logger";
+
+interface EnvironmentVariables {
+  NODE_ENV: string | undefined;
+}
+
+const requiredENV = ["NODE_ENV"];
+
+class Environment {
+  public init(): void {
+    dotenv.config({ path: path.resolve(__dirname, "../../.env") });
+
+    for (const param of requiredENV) {
+      if (this.isUndefinedOrEmpty(process.env[param]))
+        throw new Error(`.env ${param} is undefined`);
+    }
+
+    // NODE_ENV Checks
+    if (this.get().NODE_ENV !== "production" && this.get().NODE_ENV !== "development")
+      throw new Error('.env NODE_ENV must be either "production" or "development"');
+
+    Logger.log("info", `Running in ${process.env.NODE_ENV} environment`);
+  }
+
+  public get(): EnvironmentVariables {
+    return {
+      NODE_ENV: process.env.NODE_ENV,
+    };
+  }
+
+  private isUndefinedOrEmpty(value: string | undefined): boolean {
+    return value === undefined || value === "";
+  }
+}
+
+export default new Environment();