Allow 0 numerical values as args.

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- Allow `0` numerical values as validator arguments. This is technically a _breaking change_, but is not _change_ per say because it should have been done since the beginning.
 - Empty strings are now valid in every rule validating strings, except `required`. This is technically a _breaking change_, but is not _change_ per say because it should have been done since the beginning.
 
 ## [1.0.2] - 2025-04-28

src/__tests__/validator.spec.ts

@@ -1,8 +1,9 @@
-import { describe, it, expect } from "vitest";
+import { describe, it, expect, test } from "vitest";
 
 import Validator from "../validator";
 import containsNonAlphanumeric from "../rules/containsNonAlphanumeric";
 import email from "../rules/email";
+import minimumValue from "../rules/minimumValue";
 import required from "../rules/required";
 import type {
   RuleConfiguration,
@@ -293,4 +294,20 @@ describe("Validator", () => {
     expect(result.rules.notEmpty.value).toBe("");
     expect(JSON.stringify(result.rules.notEmpty.custom)).toBe(JSON.stringify({ value: "   ", trimmed: "" }));
   });
+
+  test.each([0, -0])("should succeed when validation rules arguments are 0 (number)", (args) => {
+    const validator = new Validator();
+    validator.setRule("minimumValue", minimumValue);
+    const result: ValidationResult = validator.validate("age", 0, { minimumValue: args });
+    expect(result.isValid).toBe(true);
+    expect(result.rules.minimumValue.severity).toBe("information");
+  });
+
+  it.concurrent("should succeed when validation rules arguments are 0 (BigInt)", () => {
+    const validator = new Validator();
+    validator.setRule("minimumValue", minimumValue);
+    const result: ValidationResult = validator.validate("age", 0, { minimumValue: BigInt(0) });
+    expect(result.isValid).toBe(true);
+    expect(result.rules.minimumValue.severity).toBe("information");
+  });
 });

src/validator.ts

@@ -187,7 +187,8 @@ class Validator {
       }
 
       const args: unknown = rules[key];
-      if (!args) {
+      if (typeof args === "undefined" || args === null || args === false || args === "" || (typeof args === "number" && isNaN(args))) {
+        // NOTE(fpion): 0, -0 and 0n (BigInt) are considered valid arguments.
         continue;
       }