diff --git a/test/core/round-test.js b/test/core/round-test.js
new file mode 100644
index 00000000..7d045e11
--- /dev/null
+++ b/test/core/round-test.js
@@ -0,0 +1,70 @@
+require("../env");
+require("../../d3");
+
+var vows = require("vows"),
+    assert = require("assert");
+
+var suite = vows.describe("d3.round");
+
+suite.addBatch({
+  "round": {
+    topic: function() {
+      return d3.round;
+    },
+    "returns a number": function(round) {
+      assert.isNumber(round(42));
+    },
+    "returns zero for zero": function(round) {
+      assert.equal(round(0), 0);
+    },
+    "ignores degenerate input": function(round) {
+      assert.isNaN(round(NaN));
+      assert.equal(round(Infinity), Infinity);
+      assert.equal(round(-Infinity), -Infinity);
+    },
+    "returns integers by default": function(round) {
+      assert.equal(round(10.6), 11);
+      assert.equal(round(10.4), 10);
+      assert.equal(round(0.6), 1);
+      assert.equal(round(0.4), 0);
+      assert.equal(round(-0.6), -1);
+      assert.equal(round(-0.4), 0);
+      assert.equal(round(-10.6), -11);
+      assert.equal(round(-10.4), -10);
+    },
+    "rounds to the specified decimal place": function(round) {
+      assert.inDelta(round(10.56, 1), 10.6, 1e-6);
+      assert.inDelta(round(10.54, 1), 10.5, 1e-6);
+      assert.inDelta(round(0.56, 1), 0.6, 1e-6);
+      assert.inDelta(round(0.54, 1), 0.5, 1e-6);
+      assert.inDelta(round(-0.56, 1), -0.6, 1e-6);
+      assert.inDelta(round(-0.54, 1), -0.5, 1e-6);
+      assert.inDelta(round(-10.56, 1), -10.6, 1e-6);
+      assert.inDelta(round(-10.54, 1), -10.5, 1e-6);
+      assert.inDelta(round(10.556, 2), 10.56, 1e-6);
+      assert.inDelta(round(10.554, 2), 10.55, 1e-6);
+      assert.inDelta(round(0.556, 2), 0.56, 1e-6);
+      assert.inDelta(round(0.554, 2), 0.55, 1e-6);
+      assert.inDelta(round(-0.556, 2), -0.56, 1e-6);
+      assert.inDelta(round(-0.554, 2), -0.55, 1e-6);
+      assert.inDelta(round(-10.556, 2), -10.56, 1e-6);
+      assert.inDelta(round(-10.554, 2), -10.55, 1e-6);
+    },
+    "rounds to the specified significant digits": function(round) {
+      assert.equal(round(123.45, -1), 120);
+      assert.equal(round(345.67, -1), 350);
+      assert.equal(round(-123.45, -1), -120);
+      assert.equal(round(-345.67, -1), -350);
+      assert.equal(round(123.45, -2), 100);
+      assert.equal(round(456.78, -2), 500);
+      assert.equal(round(-123.45, -2), -100);
+      assert.equal(round(-456.78, -2), -500);
+      assert.equal(round(123.45, -3), 0);
+      assert.equal(round(567.89, -3), 1000);
+      assert.equal(round(-123.45, -3), 0);
+      assert.equal(round(-567.89, -3), -1000);
+    }
+  }
+});
+
+suite.export(module);
diff --git a/test/core/test-round.js b/test/core/test-round.js
deleted file mode 100644
index eba2b6f8..00000000
--- a/test/core/test-round.js
+++ /dev/null
@@ -1,75 +0,0 @@
-require("./../../lib/env-js/envjs/node");
-require("./../../d3");
-
-console.log("degenerate:");
-console.log("          0 ->", d3.round(0));
-console.log("        NaN ->", d3.round(NaN));
-console.log("   Infinity ->", d3.round(Infinity));
-console.log("  -Infinity ->", d3.round(-Infinity));
-console.log("");
-
-console.log("default:");
-console.log("      10.51 ->", d3.round(10.51));
-console.log("      10.50 ->", d3.round(10.50));
-console.log("      10.49 ->", d3.round(10.49));
-console.log("       0.51 ->", d3.round(0.51));
-console.log("       0.50 ->", d3.round(0.50));
-console.log("       0.49 ->", d3.round(0.49));
-console.log("      -0.51 ->", d3.round(-0.51));
-console.log("      -0.50 ->", d3.round(-0.50));
-console.log("      -0.49 ->", d3.round(-0.49));
-console.log("     -10.51 ->", d3.round(-10.51));
-console.log("     -10.50 ->", d3.round(-10.50));
-console.log("     -10.49 ->", d3.round(-10.49));
-console.log("");
-
-console.log("precision 1:");
-console.log("      10.51 ->", d3.round(10.51, 1));
-console.log("      10.50 ->", d3.round(10.50, 1));
-console.log("      10.49 ->", d3.round(10.49, 1));
-console.log("       0.51 ->", d3.round(0.51, 1));
-console.log("       0.50 ->", d3.round(0.50, 1));
-console.log("       0.49 ->", d3.round(0.49, 1));
-console.log("      -0.51 ->", d3.round(-0.51, 1));
-console.log("      -0.50 ->", d3.round(-0.50, 1));
-console.log("      -0.49 ->", d3.round(-0.49, 1));
-console.log("     -10.51 ->", d3.round(-10.51, 1));
-console.log("     -10.50 ->", d3.round(-10.50, 1));
-console.log("     -10.49 ->", d3.round(-10.49, 1));
-console.log("");
-
-console.log("precision 2:");
-console.log("      10.51 ->", d3.round(10.51, 2));
-console.log("      10.50 ->", d3.round(10.50, 2));
-console.log("      10.49 ->", d3.round(10.49, 2));
-console.log("       0.51 ->", d3.round(0.51, 2));
-console.log("       0.50 ->", d3.round(0.50, 2));
-console.log("       0.49 ->", d3.round(0.49, 2));
-console.log("      -0.51 ->", d3.round(-0.51, 2));
-console.log("      -0.50 ->", d3.round(-0.50, 2));
-console.log("      -0.49 ->", d3.round(-0.49, 2));
-console.log("     -10.51 ->", d3.round(-10.51, 2));
-console.log("     -10.50 ->", d3.round(-10.50, 2));
-console.log("     -10.49 ->", d3.round(-10.49, 2));
-console.log("");
-
-console.log("precision -1:");
-console.log("     123.45 ->", d3.round(123.45, -1));
-console.log("     345.67 ->", d3.round(345.67, -1));
-console.log("    -123.45 ->", d3.round(-123.45, -1));
-console.log("    -345.67 ->", d3.round(-345.67, -1));
-console.log("");
-
-console.log("precision -2:");
-console.log("     123.45 ->", d3.round(123.45, -2));
-console.log("     456.78 ->", d3.round(456.78, -2));
-console.log("    -123.45 ->", d3.round(-123.45, -2));
-console.log("    -456.78 ->", d3.round(-456.78, -2));
-console.log("");
-
-console.log("precision -3:");
-console.log("     123.45 ->", d3.round(123.45, -3));
-console.log("     567.89 ->", d3.round(567.89, -3));
-console.log("    -123.45 ->", d3.round(-123.45, -3));
-console.log("    -567.89 ->", d3.round(-567.89, -3));
-console.log("");
diff --git a/test/core/test-round.out b/test/core/test-round.out
deleted file mode 100644
index f2063b7b..00000000
--- a/test/core/test-round.out
+++ /dev/null
@@ -1,66 +0,0 @@
-degenerate:
-          0 -> 0
-        NaN -> NaN
-   Infinity -> Infinity
-  -Infinity -> -Infinity
-
-default:
-      10.51 -> 11
-      10.50 -> 11
-      10.49 -> 10
-       0.51 -> 1
-       0.50 -> 1
-       0.49 -> 0
-      -0.51 -> -1
-      -0.50 -> 0
-      -0.49 -> 0
-     -10.51 -> -11
-     -10.50 -> -10
-     -10.49 -> -10
-
-precision 1:
-      10.51 -> 10.5
-      10.50 -> 10.5
-      10.49 -> 10.5
-       0.51 -> 0.5
-       0.50 -> 0.5
-       0.49 -> 0.5
-      -0.51 -> -0.5
-      -0.50 -> -0.5
-      -0.49 -> -0.5
-     -10.51 -> -10.5
-     -10.50 -> -10.5
-     -10.49 -> -10.5
-
-precision 2:
-      10.51 -> 10.51
-      10.50 -> 10.5
-      10.49 -> 10.49
-       0.51 -> 0.51
-       0.50 -> 0.5
-       0.49 -> 0.49
-      -0.51 -> -0.51
-      -0.50 -> -0.5
-      -0.49 -> -0.49
-     -10.51 -> -10.51
-     -10.50 -> -10.5
-     -10.49 -> -10.49
-
-precision -1:
-     123.45 -> 120
-     345.67 -> 350
-    -123.45 -> -120
-    -345.67 -> -350
-
-precision -2:
-     123.45 -> 100
-     456.78 -> 500
-    -123.45 -> -100
-    -456.78 -> -500
-
-precision -3:
-     123.45 -> 0
-     567.89 -> 1000
-    -123.45 -> 0
-    -567.89 -> -1000
-