public void GetSet_when_l1_misses_then_l2_called()
        {
            // Arrange
            var l1     = false;
            var l2     = false;
            var level1 = new InspectableCache((key) => { l1 = true; }, cacheMiss: true);
            var level2 = new InspectableCache((key) => { l2 = true; });

            var sut = new CompositeCache(level1, level2);

            // Act
            var result = sut.GetSet("a", () => "", TimeSpan.Zero);

            // Assert
            Assert.True(l1);
            Assert.True(l2);
        }