text: var tape = require("tape"),
      topojson = require("../");
  
  tape("topojson.untransform(topology) returns the identity function if transform is undefined", function(test) {
    var untransform = topojson.untransform(null),
        point;
    test.equal(untransform(point = {}), point);
    test.end();
  });
  
  tape("topojson.untransform(topology) returns a point-transform function if transform is defined", function(test) {
    var untransform = topojson.untransform({scale: [2, 3], translate: [4, 5]});
    test.deepEqual(untransform([16, 26]), [6, 7]);
    test.end();
  });
  
  tape("untransform(point) returns a new point", function(test) {
    var untransform = topojson.untransform({scale: [2, 3], translate: [4, 5]}),
        point = [16, 26];
    test.deepEqual(untransform(point), [6, 7]);
    test.deepEqual(point, [16, 26]);
    test.end();
  });
  
  tape("untransform(point) preserves extra dimensions", function(test) {
    var untransform = topojson.untransform({scale: [2, 3], translate: [4, 5]});
    test.deepEqual(untransform([16, 26, 42]), [6, 7, 42]);
    test.deepEqual(untransform([16, 26, "foo"]), [6, 7, "foo"]);
    test.deepEqual(untransform([16, 26, "foo", 42]), [6, 7, "foo", 42]);
    test.end();
  });
  
  tape("untransform(point) untransforms individual points", function(test) {
    var untransform = topojson.untransform({scale: [2, 3], translate: [4, 5]});
    test.deepEqual(untransform([6, 11]), [1, 2]);
    test.deepEqual(untransform([10, 17]), [3, 4]);
    test.deepEqual(untransform([14, 23]), [5, 6]);
    test.end();
  });
  
  tape("untransform(point, index) untransforms delta-encoded arcs", function(test) {
    var untransform = topojson.untransform({scale: [2, 3], translate: [4, 5]});
    test.deepEqual(untransform([6, 11], 0), [1, 2]);
    test.deepEqual(untransform([12, 23], 1), [3, 4]);
    test.deepEqual(untransform([22, 41], 2), [5, 6]);
    test.deepEqual(untransform([24, 47], 3), [1, 2]);
    test.deepEqual(untransform([30, 59], 4), [3, 4]);
    test.deepEqual(untransform([40, 77], 5), [5, 6]);
    test.end();
  });
  
  tape("untransform(point, index) untransforms multiple delta-encoded arcs", function(test) {
    var untransform = topojson.untransform({scale: [2, 3], translate: [4, 5]});
    test.deepEqual(untransform([6, 11], 0), [1, 2]);
    test.deepEqual(untransform([12, 23], 1), [3, 4]);
    test.deepEqual(untransform([22, 41], 2), [5, 6]);
    test.deepEqual(untransform([6, 11], 0), [1, 2]);
    test.deepEqual(untransform([12, 23], 1), [3, 4]);
    test.deepEqual(untransform([22, 41], 2), [5, 6]);
    test.end();
  });
  