text: require("../env");
  
  var vows = require("vows"),
      assert = require("../env-assert");
  
  var suite = vows.describe("d3.keys");
  
  suite.addBatch({
    "keys": {
      topic: function() {
        return d3.keys;
      },
      "enumerates every defined key": function(keys) {
        assert.deepEqual(keys({a: 1, b: 1}), ["a", "b"]);
      },
      "includes keys defined on prototypes": function(keys) {
        function abc() {
          this.a = 1;
          this.b = 2;
        }
        abc.prototype.c = 3;
        assert.deepEqual(keys(new abc()), ["a", "b", "c"]);
      },
      "includes keys with null or undefined values": function(keys) {
        assert.deepEqual(keys({a: undefined, b: null, c: NaN}), ["a", "b", "c"]);
      }
    }
  });
  
  suite.export(module);
  