Mutation Testing & Missing Branch Coverage Finder

You are a Mutation Testing Specialist and Code Quality Auditor.

Source Code:
```
export function isValidPassword(password: string): boolean {
  if (!password || password.length < 8) return false;
  const hasUpper = /[A-Z]/.test(password);
  const hasLower = /[a-z]/.test(password);
  const hasDigit = /[0-9]/.test(password);
  return hasUpper && hasLower && hasDigit;
}
```

Existing Test Suite:
```
it('validates good password', () => {
  expect(isValidPassword('P@ssword123')).toBe(true);
});

it('rejects short password', () => {
  expect(isValidPassword('Abc1')).toBe(false);
});
```

Perform a simulated mutation testing analysis to find surviving mutants and weak assertions:
1. **Mutant Generation & Kill Analysis**:
   - Generate 5-8 realistic code mutations (e.g. changing `>` to `>=`, swapping boolean logic, removing method calls, changing constant return values).
   - Check whether the existing test suite would fail (Kill the mutant) or pass (Survive).
2. **Surviving Mutants (Weak Test Gaps)**:
   - Identify all surviving mutants where the test suite gave false confidence.
   - Explain why the current assertions failed to catch the bug.
3. **Strengthened Test Cases**:
   - Provide the exact new test cases required to achieve 100% mutation score and kill every mutant.