// Invalid inputs: negative sizes for constructor arguments
    @Nested
    class InvalidConstruction {
        @Test
        @DisplayName("Negative maxBuffers throws immediately in constructor")
        void negativeMaxBuffersThrows() {
            assertThrows(NegativeArraySizeException.class, () -> new BufferCacheImpl(-1, 10));
        }

        @Test
        @DisplayName("Negative maxSize throws when allocating a new buffer")