Merge pull request #2 from knpwrs/require-env

Add requireEnv function

lib/helpers.ts

@@ -38,6 +38,15 @@ export class UnsupportedEnvironmentError extends Error {
     }
 }
 
+/**
+ * Error thrown when attempting to retrieve undefined environment variables.
+ */
+export class UndefinedEnvironmentError extends Error {
+    constructor(key: string) {
+        super(`${key} not defined in environment.`);
+    }
+}
+
 /**
  * Error thrown when attempting to validate an environment variable.
  */

mod.ts

@@ -4,7 +4,7 @@
  *                retrieving environment variables across Deno, Bun and Node.js
  */
 
-import { EnvOptions, UnsupportedEnvironmentError, ValidationError, ValidatorFunction } from "./lib/helpers.ts";
+import { EnvOptions, UndefinedEnvironmentError, UnsupportedEnvironmentError, ValidationError, ValidatorFunction } from "./lib/helpers.ts";
 import { deepMerge } from "@cross/deepmerge";
 import { getCurrentRuntime } from "@cross/runtime";
 import { loadEnvFile } from "./lib/filehandler.ts";
@@ -103,6 +103,27 @@ export function getEnv(key: string): string | undefined {
     }
 }
 
+/**
+ * Gets an environment variable across different supported runtimes and throws
+ * an error if the environment variable is not defined.
+ *
+ * @param {string} key - The name of the environment variable.
+ * @returns {string} The value of the environment variable, or undefined if not found.
+ * @throws {UndefinedEnvironmentError} if the current runtime is unsupported
+ *         and the 'throwErrors' flag is set.
+ * @throws {UnsupportedEnvironmentError} if the current runtime is unsupported
+ *         and the 'throwErrors' flag is set.
+ */
+export function requireEnv(key: string): string {
+    const value = getEnv(key);
+
+    if (!value) {
+        throw new UndefinedEnvironmentError(key);
+    }
+
+    return value;
+}
+
 /**
  * Set an environment variable in supported runtimes.
  *

tests/deno.ts

@@ -4,6 +4,7 @@ import {
     getAllEnv,
     getEnv,
     hasEnv,
+    requireEnv,
     setEnv,
     setupEnv,
     validateAndGetEnv,
@@ -32,6 +33,26 @@ Deno.test({
     },
 });
 
+/** ==== requireEnv() ==== */
+Deno.test({
+    name: "requireEnv() retrieves an existing environment variable",
+    fn() {
+        Deno.env.set("TEST_VARIABLE", "hello");
+
+        const value = requireEnv("TEST_VARIABLE");
+        assertEquals(value, "hello");
+
+        Deno.env.delete("TEST_VARIABLE");
+    },
+});
+
+Deno.test({
+    name: "requireEnv() throws for nonexistant keys",
+    fn: () => {
+        assertThrows(() => requireEnv("TEST_KEY_NONEXISTANT"), "TEST_KEY_NONEXISTANT not defined in environment.")
+    },
+});
+
 /** ==== getAllEnv() ==== */
 Deno.test({
     name: "getAllEnv() with prefix filters variables",