package com.peachpasswords.vault import org.junit.Assert.assertEquals import org.junit.Assert.assertNull import org.junit.Test class PinUnlockStoreTest { @Test fun pin_policy_requires_four_to_twelve_ascii_digits() { assertEquals("PIN must be 4–12 digits", pinValidationError("123")) assertEquals("PIN must contain digits only", pinValidationError("12a4")) assertNull(pinValidationError("1234")) assertNull(pinValidationError("123456789012")) } }