Add comprehensive unit tests for core classes

[Copilot]

Expanded test coverage from 4 basic instantiation tests to 67 comprehensive tests covering all core classes.

New Test Coverage

• CryptoUtilsTest (17 tests): Token/session ID generation validation, password hashing consistency, edge cases with special characters
• FileControllerTest (13 tests): File I/O operations, multiline content, command execution behavior
• UserDatabaseTest (15 tests): Database operations with SQL injection patterns, empty/long values, sequential operations
• LdapAuthTest (18 tests): LDAP authentication flows, injection patterns, unicode handling

Test Characteristics

Tests verify graceful failure handling when external services (MySQL, LDAP) are unavailable and validate method behavior across edge cases including empty strings, special characters, unicode, and malicious input patterns.

@Test
public void testHashPasswordConsistency() {
    String password = "testPassword";
    String hash1 = cryptoUtils.hashPassword(password);
    String hash2 = cryptoUtils.hashPassword(password);
    assertEquals("Same password should produce same hash", hash1, hash2);
}

Original prompt

create me some more unit tests for this code base

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