diff --git a/test/core/ns-test.js b/test/core/ns-test.js
new file mode 100644
index 00000000..a100c468
--- /dev/null
+++ b/test/core/ns-test.js
@@ -0,0 +1,53 @@
+require("../env");
+require("../../d3");
+
+var vows = require("vows"),
+    assert = require("assert");
+
+var suite = vows.describe("ns");
+
+suite.addBatch({
+  "prefix": {
+    topic: function() {
+      return d3.ns.prefix;
+    },
+    "svg is http://www.w3.org/2000/svg": function(prefix) {
+      assert.equal(prefix.svg, "http://www.w3.org/2000/svg");
+    },
+    "xhtml is http://www.w3.org/1999/xhtml": function(prefix) {
+      assert.equal(prefix.xhtml, "http://www.w3.org/1999/xhtml");
+    },
+    "xlink is http://www.w3.org/1999/xlink": function(prefix) {
+      assert.equal(prefix.xlink, "http://www.w3.org/1999/xlink");
+    },
+    "xml is http://www.w3.org/XML/1998/namespace": function(prefix) {
+      assert.equal(prefix.xml, "http://www.w3.org/XML/1998/namespace");
+    },
+    "xmlns is http://www.w3.org/2000/xmlns/": function(prefix) {
+      assert.equal(prefix.xmlns, "http://www.w3.org/2000/xmlns/");
+    }
+  }
+});
+
+suite.addBatch({
+  "qualify": {
+    topic: function() {
+      return d3.ns.qualify;
+    },
+    "local name returns name": function() {
+      assert.equal(d3.ns.qualify("local"), "local");
+    },
+    "known qualified name returns space and local": function() {
+      var name = d3.ns.qualify("svg:path");
+      assert.equal(name.space, "http://www.w3.org/2000/svg");
+      assert.equal(name.local, "path");
+    },
+    "unknown qualified name returns undefined and local": function() {
+      var name = d3.ns.qualify("foo:bar");
+      assert.isUndefined(name.space);
+      assert.equal(name.local, "bar");
+    }
+  }
+});
+
+suite.export(module);