Edge Case Generator

- Minimum value (e.g., INT_MIN, 0, -∞)
- Maximum value (e.g., INT_MAX, 255, +∞)
- Zero
- One (unit value)
- Negative one
- Just below/above boundaries
- Overflow/underflow values

- Empty collection
- Single element
- Two elements (minimal interaction)
- Maximum size (if bounded)
- All identical elements
- All unique elements
- Sorted vs unsorted
- Contains duplicates

- Empty string ("")
- Single character
- Very long string (10K+ chars)
- Unicode characters (emoji, RTL, special)
- Whitespace only ("   ")
- Null terminator issues
- Special characters (\n, \t, \0)

- Null/None/undefined
- Dangling pointer
- Self-reference (circular)
- Uninitialized

- Uninitialized state
- Partially initialized
- Valid operational state
- Invalid/corrupted state
- Locked/busy state
- Disposed/freed state

- Missing required parameters
- Parameters in wrong order
- Invalid combinations
- Violated invariants

- Typical successful execution
- Boundary successful case
- Empty result (valid but empty)

- Expected exceptions/errors
- Timeout scenarios
- Partial failures
- Resource exhaustion

- First operation
- Last operation
- Repeated operations
- Alternating operations
- Concurrent operations

- Missing dependencies
- Circular dependencies
- Incompatible versions
- Network failures

# Example: Testing a function that calculates factorial
def test_factorial_edge_cases():
    # Zero (boundary)
    assert factorial(0) == 1

    # One (boundary)
    assert factorial(1) == 1

    # Negative (invalid input)
    with pytest.raises(ValueError):
        factorial(-1)

    # Large value (overflow risk)
    with pytest.raises(OverflowError):
        factorial(10000)

    # Non-integer (type boundary)
    with pytest.raises(TypeError):
        factorial(3.5)

// Example: Testing an array processing function
describe('processArray edge cases', () => {
  test('empty array', () => {
    expect(processArray([])).toEqual([]);
  });

  test('single element', () => {
    expect(processArray([1])).toEqual([1]);
  });

  test('null input', () => {
    expect(() => processArray(null)).toThrow(TypeError);
  });

  test('undefined input', () => {
    expect(() => processArray(undefined)).toThrow(TypeError);
  });

  test('all identical elements', () => {
    expect(processArray([5, 5, 5, 5])).toEqual([5, 5, 5, 5]);
  });

  test('very large array', () => {
    const largeArray = new Array(1000000).fill(1);
    expect(() => processArray(largeArray)).not.toThrow();
  });
});

// Example: Testing string validation
@Test
public void testValidateString_EdgeCases() {
    // Empty string
    assertThrows(ValidationException.class, () -> validateString(""));

    // Null
    assertThrows(NullPointerException.class, () -> validateString(null));

    // Single character
    assertTrue(validateString("a"));

    // Whitespace only
    assertFalse(validateString("   "));

    // Special characters
    assertTrue(validateString("hello@world!"));

    // Unicode
    assertTrue(validateString("你好世界"));

    // Very long string
    String longString = "a".repeat(100000);
    assertDoesNotThrow(() -> validateString(longString));

    // Control characters
    assertFalse(validateString("hello\0world"));
}

// Example: Testing pointer operations
void test_pointer_edge_cases() {
    // Null pointer
    assert(safe_strlen(NULL) == -1);

    // Empty string
    assert(safe_strlen("") == 0);

    // Single character
    assert(safe_strlen("a") == 1);

    // Very long string
    char long_str[10000];
    memset(long_str, 'a', 9999);
    long_str[9999] = '\0';
    assert(safe_strlen(long_str) == 9999);
}

// Example: Testing concurrent access
func TestConcurrentAccess(t *testing.T) {
    cache := NewCache()

    // Race condition: multiple concurrent writes
    t.Run("concurrent writes", func(t *testing.T) {
        var wg sync.WaitGroup
        for i := 0; i < 100; i++ {
            wg.Add(1)
            go func(val int) {
                defer wg.Done()
                cache.Set("key", val)
            }(i)
        }
        wg.Wait()
        // Verify cache is in valid state
        _, ok := cache.Get("key")
        assert.True(t, ok)
    })

    // Deadlock scenario
    t.Run("potential deadlock", func(t *testing.T) {
        done := make(chan bool)
        go func() {
            cache.Set("key1", 1)
            cache.Set("key2", 2)
            done <- true
        }()

        select {
        case <-done:
            // Success
        case <-time.After(5 * time.Second):
            t.Fatal("Deadlock detected")
        }
    })
}

# Example: Testing state machine
def test_state_machine_edge_cases():
    machine = StateMachine()

    # Invalid initial transition
    with pytest.raises(InvalidStateError):
        machine.stop()  # Can't stop before starting

    # Double start
    machine.start()
    with pytest.raises(InvalidStateError):
        machine.start()  # Already started

    # Transition from error state
    machine.trigger_error()
    with pytest.raises(InvalidStateError):
        machine.resume()  # Can't resume from error

    # Valid state sequence
    machine.reset()
    machine.start()
    machine.pause()
    machine.resume()
    machine.stop()
    assert machine.state == "stopped"

# Example: Testing memory and resource limits
def test_resource_limits():
    # Memory exhaustion
    with pytest.raises(MemoryError):
        allocate_huge_buffer(size=10**15)

    # File handle exhaustion
    handles = []
    try:
        for i in range(10000):
            handles.append(open(f'/tmp/test_{i}', 'w'))
    except OSError as e:
        assert "Too many open files" in str(e)
    finally:
        for h in handles:
            h.close()

    # Timeout scenarios
    with pytest.raises(TimeoutError):
        slow_operation(timeout=0.001)  # Very short timeout

    # Disk full simulation
    with patch('os.write', side_effect=OSError("No space left on device")):
        with pytest.raises(OSError):
            write_large_file()

# For a function that accepts age (0-120)
# Partitions: Invalid (<0), Valid (0-120), Invalid (>120)

def test_age_validation():
    # Invalid: negative
    assert not is_valid_age(-1)
    assert not is_valid_age(-100)

    # Valid: boundaries
    assert is_valid_age(0)
    assert is_valid_age(120)

    # Valid: typical
    assert is_valid_age(25)
    assert is_valid_age(65)

    # Invalid: too large
    assert not is_valid_age(121)
    assert not is_valid_age(1000)

// For array index access (0 to length-1)
describe('array access boundaries', () => {
  const arr = [10, 20, 30, 40, 50];

  test('before first element', () => {
    expect(() => arr.at(-1)).toThrow(RangeError);
  });

  test('first element (boundary)', () => {
    expect(arr.at(0)).toBe(10);
  });

  test('second element (just inside)', () => {
    expect(arr.at(1)).toBe(20);
  });

  test('last element (boundary)', () => {
    expect(arr.at(4)).toBe(50);
  });

  test('after last element', () => {
    expect(() => arr.at(5)).toThrow(RangeError);
  });
});

from hypothesis import given, strategies as st

@given(st.lists(st.integers()))
def test_sort_properties(input_list):
    """Property: sorted list length equals input length"""
    result = sort(input_list)
    assert len(result) == len(input_list)

@given(st.lists(st.integers(), min_size=1))
def test_max_element_property(input_list):
    """Property: max element >= all elements"""
    max_val = find_max(input_list)
    assert all(max_val >= x for x in input_list)

@given(st.text())
def test_string_reverse_property(s):
    """Property: reversing twice returns original"""
    assert reverse(reverse(s)) == s

# Original function
def is_even(n):
    return n % 2 == 0

# Mutant 1: Changed == to !=
def is_even_mutant1(n):
    return n % 2 != 0  # Should be caught by tests

# Test that catches this mutation
def test_is_even():
    assert is_even(0) == True   # Catches mutant1
    assert is_even(1) == False  # Catches mutant1
    assert is_even(2) == True   # Catches mutant1