tests: []testFnc{
			testWrite{"ab", 2, nil},
			testRemaining{6, 3},
			testReadFrom{fileOps{int64(3), "cde"}, 6, nil},
			testRemaining{0, 0},
		},
	}, {
		maker: makeSparse{makeReg{5, "abcde"}, sparseHoles{{2, 3}}, 8},
		tests: []testFnc{
			testReadFrom{fileOps{"ab", int64(3), "cde"}, 8, nil},
			testRemaining{0, 0},
		},
	}, {
		maker: makeSparse{makeReg{5, "abcde"}, sparseHoles{{2, 3}}, 8},

	root, path, want string
}

var reltests = []RelTests{
	{"a/b", "a/b", "."},
	{"a/b/.", "a/b", "."},
	{"a/b", "a/b/.", "."},
	{"./a/b", "a/b", "."},
	{"a/b", "./a/b", "."},
	{"ab/cd", "ab/cde", "../cde"},
	{"ab/cd", "ab/c", "../c"},
	{"a/b", "a/b/c/d", "c/d"},
	{"a/b", "a/b/../c", "../c"},
	{"a/b/../c", "a/b", "../b"},
	{"a/b/c", "a/c/d", "../../c/d"},
	{"a/b", "c/d", "../../c/d"},