emptyMap,
		},
	}}

	for _, tc := range cases {
		var permutations [][]int
		if tc.testAllPermutations {
			// Run test case with all permutations of operations.
			permutations = indexPermutations(len(tc.ops))
		} else {
			// Unless test is order dependent (e.g. includes
			// deletes) or just too big.
			var p []int
			for i := 0; i < len(tc.ops); i++ {
				p = append(p, i)
			}