Add test for d3.version.

test/core/version-test.js

@@ -0,0 +1,18 @@
+require("../env");
+require("../../d3");
+
+var vows = require("vows"),
+    assert = require("assert");
+
+var suite = vows.describe("d3.version");
+
+suite.addBatch({
+  "semantic versioning": {
+    topic: d3.version,
+    "has the form major.minor.patch": function(version) {
+      assert.match(version, /^[0-9]+\.[0-9]+\.[0-9]+$/);
+    }
+  }
+});
+
+suite.export(module);