From 6d81eaba4b64c141267f3a1c3128ec50e7f3ba7d Mon Sep 17 00:00:00 2001
From: Ilia Mashkov <hikkikomori7@gmail.com>
Date: Wed, 25 Mar 2026 10:34:54 +0300
Subject: [PATCH] feat(auth): add validatePassword function with requirements
 for min and max characters amount, presence of at least one uppercase letter,
 one lowercase letter, one digit and one special symbol; cover it with tests

---
 src/features/auth/lib/validators/index.ts     |  1 +
 .../validatePassword/validatePassword.spec.ts | 66 +++++++++++++++++++
 .../validatePassword/validatePassword.ts      | 19 ++++++
 .../auth/model/stores/authStore/authStore.ts  |  6 +-
 4 files changed, 87 insertions(+), 5 deletions(-)
 create mode 100644 src/features/auth/lib/validators/validatePassword/validatePassword.spec.ts
 create mode 100644 src/features/auth/lib/validators/validatePassword/validatePassword.ts

diff --git a/src/features/auth/lib/validators/index.ts b/src/features/auth/lib/validators/index.ts
index beaa628..ff7f5c9 100644
--- a/src/features/auth/lib/validators/index.ts
+++ b/src/features/auth/lib/validators/index.ts
@@ -1 +1,2 @@
 export { validateEmail } from "./validateEmail/validateEmail";
+export { validatePassword } from "./validatePassword/validatePassword";
diff --git a/src/features/auth/lib/validators/validatePassword/validatePassword.spec.ts b/src/features/auth/lib/validators/validatePassword/validatePassword.spec.ts
new file mode 100644
index 0000000..69dc34c
--- /dev/null
+++ b/src/features/auth/lib/validators/validatePassword/validatePassword.spec.ts
@@ -0,0 +1,66 @@
+import {
+  MAX_PASSWORD_LENGTH,
+  MIN_PASSWORD_LENGTH,
+  validatePassword,
+} from "./validatePassword";
+
+describe("validatePassword", () => {
+  describe("Absence of necessary characters", () => {
+    it("should return false when the password does not contain a lowercase letter", () => {
+      expect(validatePassword("PASSWORD123!")).toBe(false);
+    });
+    it("should return false when the password does not contain an uppercase letter", () => {
+      expect(validatePassword("password123!")).toBe(false);
+    });
+    it("should return false when the password does not contain a digit", () => {
+      expect(validatePassword("Password!")).toBe(false);
+    });
+    it("should return false when the password does not contain a special character", () => {
+      expect(validatePassword("Password123")).toBe(false);
+    });
+  });
+
+  describe("Length requirement", () => {
+    const validChars = "aA1!";
+
+    it("should return false when the password is less than min length", () => {
+      const shortPassword =
+        validChars +
+        "a".repeat(Math.max(0, MIN_PASSWORD_LENGTH - validChars.length - 1));
+
+      expect(validatePassword(shortPassword)).toBe(false);
+    });
+    it("should return true when the password is exactly min length", () => {
+      const exactMinPassword =
+        validChars +
+        "a".repeat(Math.max(0, MIN_PASSWORD_LENGTH - validChars.length));
+
+      expect(validatePassword(exactMinPassword)).toBe(true);
+    });
+    it("should return false when the password is greater than max length", () => {
+      const longPassword =
+        validChars +
+        "a".repeat(Math.max(0, MAX_PASSWORD_LENGTH - validChars.length + 1));
+
+      expect(validatePassword(longPassword)).toBe(false);
+    });
+    it("should return true when the password is exactly max length", () => {
+      const exactMaxPassword =
+        validChars +
+        "a".repeat(Math.max(0, MAX_PASSWORD_LENGTH - validChars.length));
+
+      expect(validatePassword(exactMaxPassword)).toBe(true);
+    });
+  });
+
+  describe("Valid password", () => {
+    it("should return true when the password is valid", () => {
+      const validChars = "aA1!";
+      const validPassword =
+        validChars +
+        "a".repeat(Math.max(0, MIN_PASSWORD_LENGTH - validChars.length));
+
+      expect(validatePassword(validPassword)).toBe(true);
+    });
+  });
+});
diff --git a/src/features/auth/lib/validators/validatePassword/validatePassword.ts b/src/features/auth/lib/validators/validatePassword/validatePassword.ts
new file mode 100644
index 0000000..5c35970
--- /dev/null
+++ b/src/features/auth/lib/validators/validatePassword/validatePassword.ts
@@ -0,0 +1,19 @@
+export const MIN_PASSWORD_LENGTH = 11;
+export const MAX_PASSWORD_LENGTH = 63;
+
+/**
+ * The password regex used to validate passwords.
+ * Uses a case-sensitive regex with at least one lowercase letter, one uppercase letter, one digit, and one special character.
+ */
+export const PASSWORD_REGEX = new RegExp(
+  `^(?=.*[a-z])(?=.*[A-Z])(?=.*\\d)(?=.*[@$!%*?&])[A-Za-z\\d@$!%*?&]{${MIN_PASSWORD_LENGTH},${MAX_PASSWORD_LENGTH}}$`,
+);
+
+/**
+ * Validates a password against the password regex.
+ * @param password The password to validate.
+ * @returns `true` if the password is valid, `false` otherwise.
+ */
+export function validatePassword(password: string): boolean {
+  return PASSWORD_REGEX.test(password);
+}
diff --git a/src/features/auth/model/stores/authStore/authStore.ts b/src/features/auth/model/stores/authStore/authStore.ts
index 84300d6..9bdc9b3 100644
--- a/src/features/auth/model/stores/authStore/authStore.ts
+++ b/src/features/auth/model/stores/authStore/authStore.ts
@@ -4,7 +4,7 @@ import { login, logout, register } from "../../../api";
 import { callApi } from "shared/utils";
 import { UNEXPECTED_ERROR_MESSAGE } from "shared/api";
 import { selectAuthData, selectFormValid } from "../../selectors";
-import { validateEmail } from "../../../lib";
+import { validateEmail, validatePassword } from "../../../lib";
 
 export const defaultStoreState: Readonly<AuthStoreState> = {
   formData: {
@@ -16,10 +16,6 @@ export const defaultStoreState: Readonly<AuthStoreState> = {
   error: null,
 };
 
-function validatePassword(password: string): boolean {
-  return Boolean(password);
-}
-
 export const useAuthStore = create<AuthStore>()((set, get) => ({
   ...defaultStoreState,