feat: 🧑‍💻 Allow single-argument call of initVariable(envVariable: string), defaulting to the OPTIONAL built-in validator

Author: pklaschka

mod.ts

@@ -56,7 +56,7 @@ export class EnvNotSetError extends Error {
  * 5. Validate the environment variable's value using `validator`.
  *
  * @param envVariable name of the environment variable
- * @param validator Zod schema used to validate the environment variable's value
+ * @param validator Zod schema used to validate the environment variable's value. Defaults to {@link OPTIONAL}.
  * @param defaultValue default value for the environment variable
  *
  * @throws {ConfigParseError} If the final environment variable's value cannot be parsed using `validator`,
@@ -66,7 +66,7 @@ export class EnvNotSetError extends Error {
  */
 export async function initVariable(
   envVariable: string,
-  validator: ZodSchemaCompat,
+  validator: ZodSchemaCompat = OPTIONAL,
   defaultValue?: string,
 ): Promise<void> {
   logger().debug(`(${envVariable}) Setting up environment variable.`, {

mod_test.ts

@@ -296,6 +296,23 @@ Deno.test("initVariable", async (t) => {
 			"Expected the value to be undefined",
 		);
 	});
+
+	await t.step("Single Argument defaults to OPTIONAL", async (t) => {
+		prepare("XXX");
+		await initVariable(ENV_VAR);
+		await assertEquals(
+			Deno.env.get(ENV_VAR),
+			"XXX",
+			"Expected the value to be undefined",
+		);
+		prepare();
+		await initVariable(ENV_VAR);
+		await assertEquals(
+			Deno.env.get(ENV_VAR),
+			undefined,
+			"Expected the value to be undefined",
+		);
+	});
 });
 
 Deno.test("Built-in ZodSchemaCompat Validators", async (t) => {
@@ -332,7 +349,7 @@ Deno.test("Built-in ZodSchemaCompat Validators", async (t) => {
 		[
 			"",
 		],
-	)
+	);
 
 	function testZodSchemaCompatValidator(
 		ctx: Deno.TestContext,