diff --git a/package.json b/package.json
index f800470..f6659b7 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "minimed-connect-to-nightscout",
-  "version": "0.2.2",
+  "version": "0.2.3",
   "description": "Send Medtronic pump and CGM data to Nightscout.",
   "author": "Mark Wilson <mark@warkmilson.com>",
   "repository": {
@@ -12,13 +12,21 @@
   },
   "main": "index.js",
   "scripts": {
-    "start": "node run.js"
+    "start": "node run.js",
+    "test": "mocha"
   },
   "license": "MIT",
+  "engines": {
+    "node": "0.10.x"
+  },
   "dependencies": {
-    "common": "0.2.5",
-    "extend": "3.0.0",
-    "request": "2.64.0"
+    "common": "0.2.x",
+    "extend": "3.0.x",
+    "request": "2.64.x"
+  },
+  "devDependencies": {
+    "expect.js": "0.3.x",
+    "mocha": "2.3.x"
   },
   "keywords": [
     "medtronic",
diff --git a/test/fixtures.js b/test/fixtures.js
new file mode 100644
index 0000000..de3dc4b
--- /dev/null
+++ b/test/fixtures.js
@@ -0,0 +1,93 @@
+var extend = require('extend');
+
+var makeSG = module.exports.makeSG = function(sg, time) {
+  time = time || "Oct 20, 2015 11:09:00";
+  return {
+    "sg" : sg,
+    "datetime" : time,
+    "version" : 1,
+    "timeChange" : false,
+    "kind" : "SG"
+  };
+};
+
+var makeSGs = module.exports.makeSGs = function(count) {
+  var out = [];
+  for(var i = 0; i < count; i++) {
+    out.push(makeSG(100 + i));
+  }
+  return out;
+};
+
+var data = module.exports.data = function(overrides) {
+  overrides = overrides || {};
+  return extend(true, {
+      "sgs" : makeSGs(300),
+      "conduitSerialNumber" : "0",
+      "conduitMedicalDeviceInRange" : true,
+      "version" : 1,
+      "calibStatus" : "LESS_THAN_TWELVE_HRS",
+      "medicalDeviceFamily" : "PARADIGM",
+      "kind" : "Main",
+      "medicalDeviceTime" : 0,
+      "lastAlarm" : {
+         "type" : "ALARM",
+         "version" : 1,
+         "flash" : false,
+         "datetime" : "Oct 12, 2015 03:12:10",
+         "kind" : "Alarm",
+         "code" : 102
+      },
+      "currentServerTime" : 1445091119507,
+      "sMedicalDeviceTime" : "Oct 17, 2015 09:09:14",
+      "conduitInRange" : true,
+      "limits" : [
+         {
+            "index" : 0,
+            "lowLimit" : 80,
+            "kind" : "Limits",
+            "highLimit" : 300,
+            "version" : 1
+         }
+      ],
+      "reservoirAmount" : 52,
+      "timeFormat" : "HR_24",
+      "sensorState" : "NORMAL",
+      "lastConduitTime" : 0,
+      "medicalDeviceBatteryLevelPercent" : 100,
+      "reservoirLevelPercent" : 50,
+      // We don't look at this; otherwise it should match "sgs"
+      "lastSG" : {
+         "kind" : "SG",
+         "datetime" : "Oct 17, 2015 09:08:00",
+         "version" : 1,
+         "timeChange" : false,
+         "sg" : 180
+      },
+      "lastSensorTSAsString" : "Oct 17, 2015 09:08:00",
+      "lastName" : "<redacted>",
+      "activeInsulin" : {
+         "datetime" : "Oct 17, 2015 09:09:14",
+         "version" : 1,
+         "amount" : 1.275,
+         "kind" : "Insulin"
+      },
+      "conduitBatteryLevel" : 100,
+      "conduitBatteryStatus" : "FULL",
+      "conduitSensorInRange" : true,
+      "medicalDeviceSerialNumber" : "<redacted>",
+      "timeToNextCalibHours" : 11,
+      "sensorDurationHours" : 91,
+      "firstName" : "<redacted>",
+      "lastConduitUpdateServerTime" : 1445091101422,
+      "lastMedicalDeviceDataUpdateServerTime" : 1445091101422,
+      "medicalDeviceSuspended" : false,
+      "bgunits" : "MGDL",
+      "bgUnits" : "MGDL",
+      "sLastSensorTime" : "Oct 17, 2015 09:08:00",
+      "lastSensorTS" : 0,
+      "medicalDeviceTimeAsString" : "Oct 17, 2015 09:09:14",
+      "lastSGTrend" : "UP_DOUBLE",
+      "lastSensorTime" : 0
+  }, overrides);
+};
diff --git a/test/transform.js b/test/transform.js
new file mode 100644
index 0000000..cec38f4
--- /dev/null
+++ b/test/transform.js
@@ -0,0 +1,51 @@
+/* jshint node: true */
+/* globals describe, it */
+"use strict";
+
+var expect = require('expect.js');
+
+var f = require('./fixtures.js'),
+  transform = require('../transform.js');
+
+describe('transform()', function() {
+  it('should obey sgvLimit', function() {
+    var data = f.data();
+
+    expect(
+      transform(data)
+        .filter(function(e) { return e['type'] === 'sgv'; })
+        .length
+    ).to.eql(data['sgs'].length);
+
+    expect(
+      transform(data, 4)
+        .filter(function(e) { return e['type'] === 'sgv'; })
+        .length
+    ).to.be(4);
+  });
+
+  it('should include pump device family', function() {
+    expect(
+      transform(
+        f.data({'medicalDeviceFamily': 'foo'})
+      )[0]['device']
+    ).to.be('connect://foo');
+  });
+
+  it('should discard data more than 20 minutes old', function() {
+    var now = Date.now();
+    var THRESHOLD = 20;
+    var boundary = now - THRESHOLD * 60 * 1000;
+    expect(
+      transform(
+        f.data({'currentServerTime': now, 'lastMedicalDeviceDataUpdateServerTime': boundary})
+      ).length
+    ).to.be.greaterThan(0);
+
+    expect(
+      transform(
+        f.data({'currentServerTime': now, 'lastMedicalDeviceDataUpdateServerTime': boundary - 1})
+      ).length
+    ).to.be(0);
+  });
+});