process.d.ts

// src/process.d.ts

declare namespace NodeJS {
  interface ProcessEnv {
    MY_ENV_VAR: string;
  }
}

ProcessEnvFacade.ts

/**
 * ProcessEnvFacade is an object that provides methods to interact with environment variables.
 * It provides methods to get, set, and validate environment variables.
 */
const ProcessEnvFacade = {
  getValueOrThrow: (key: keyof NodeJS.ProcessEnv): string => {
    const maybeKey = process.env[key];
    if (!maybeKey) {
      throw new Error(`Environment variable ${key} is not set`);
    }
    return maybeKey;
  },

  getValueOrExit: (key: keyof NodeJS.ProcessEnv): string => {
    const maybeKey = process.env[key];
    if (!maybeKey) {
      console.error(`Environment variable ${key} is not set`);
      process.exit(1);
    }
    return maybeKey;
  },

  getValue: (key: keyof NodeJS.ProcessEnv): string | undefined =>
    process.env[key],

  setValue: (key: keyof NodeJS.ProcessEnv, value: string) => {
    process.env[key] = value;
  },
};

export default ProcessEnvFacade;