wantAligned  []sparseEntry // Result of alignSparseEntries
		wantInverted []sparseEntry // Result of invertSparseEntries
	}{{
		in: []sparseEntry{}, size: 0,
		wantValid:    true,
		wantInverted: []sparseEntry{{0, 0}},
	}, {
		in: []sparseEntry{}, size: 5000,
		wantValid:    true,
		wantInverted: []sparseEntry{{0, 5000}},
	}, {
		in: []sparseEntry{{0, 5000}}, size: 5000,