diff --git a/static_src/monitoring/monorail-ts-mon.test.js b/static_src/monitoring/monorail-ts-mon.test.js
new file mode 100644
index 0000000..fdf3e81
--- /dev/null
+++ b/static_src/monitoring/monorail-ts-mon.test.js
@@ -0,0 +1,152 @@
+import {assert} from 'chai';
+import sinon from 'sinon';
+
+import MonorailTSMon, {PAGE_TYPES} from './monorail-ts-mon.js';
+
+describe('MonorailTSMon', () => {
+  let mts;
+
+  beforeEach(() => {
+    window.CS_env = {
+      token: 'rutabaga-token',
+      tokenExpiresSec: 1234,
+      app_version: 'rutabaga-version',
+    };
+    window.chops = {rpc: {PrpcClient: sinon.spy()}};
+    MonorailTSMon.prototype.disableAfterNextFlush = sinon.spy();
+    mts = new MonorailTSMon();
+  });
+
+  afterEach(() => {
+    delete window.CS_env;
+  });
+
+  describe('constructor', () => {
+    it('initializes a prpcClient', () => {
+      assert.equal(mts.prpcClient.constructor.name, 'AutoRefreshPrpcClient');
+    });
+
+    it('sets a client ID', () => {
+      assert.isNotNull(mts.clientId);
+    });
+
+    it('disables sending after next flush', () => {
+      sinon.assert.calledOnce(mts.disableAfterNextFlush);
+    });
+  });
+
+  it('generateClientId', () => {
+    const clientID = MonorailTSMon.generateClientId();
+    assert.isNotNumber(clientID);
+    const clientIDNum = parseInt(clientID, 32);
+    assert.isNumber(clientIDNum);
+    assert.isAtLeast(clientIDNum, 0);
+    assert.isAtMost(clientIDNum, Math.pow(2, 32));
+  });
+
+  describe('recordUserTiming', () => {
+    it('records a timing metric only if matches', () => {
+      const metric = {add: sinon.spy()};
+      mts._userTimingMetrics = [{
+        category: 'rutabaga',
+        eventName: 'rutabaga-name',
+        eventLabel: 'rutabaga-label',
+        metric: metric,
+      }];
+
+      mts.recordUserTiming('kohlrabi', 'rutabaga-name', 'rutabaga-label', 1);
+      sinon.assert.notCalled(metric.add);
+      metric.add.resetHistory();
+
+      mts.recordUserTiming('rutabaga', 'is-a-tuber', 'rutabaga-label', 1);
+      sinon.assert.notCalled(metric.add);
+      metric.add.resetHistory();
+
+      mts.recordUserTiming('rutabaga', 'rutabaga-name', 'went bad', 1);
+      sinon.assert.notCalled(metric.add);
+      metric.add.resetHistory();
+
+      mts.recordUserTiming('rutabaga', 'rutabaga-name', 'rutabaga-label', 1);
+      sinon.assert.calledOnce(metric.add);
+      assert.equal(metric.add.args[0][0], 1);
+      const argsKeys = Array.from(metric.add.args[0][1].keys());
+      assert.deepEqual(argsKeys, ['client_id', 'host_name', 'document_visible']);
+    });
+  });
+
+  describe('recordPageLoadTiming', () => {
+    beforeEach(() => {
+      mts.pageLoadMetric = {add: sinon.spy()};
+      sinon.stub(MonorailTSMon, 'isPageVisible').callsFake(() => (true));
+    });
+
+    afterEach(() => {
+      MonorailTSMon.isPageVisible.restore();
+    });
+
+    it('records page load on issue entry page', () => {
+      mts.recordIssueEntryTiming();
+      sinon.assert.calledOnce(mts.pageLoadMetric.add);
+      assert.isNumber(mts.pageLoadMetric.add.getCall(0).args[0]);
+      assert.isString(mts.pageLoadMetric.add.getCall(0).args[1].get(
+          'client_id'));
+      assert.equal(mts.pageLoadMetric.add.getCall(0).args[1].get(
+          'host_name'), 'rutabaga-version');
+      assert.equal(mts.pageLoadMetric.add.getCall(0).args[1].get(
+          'template_name'), 'issue_entry');
+      assert.equal(mts.pageLoadMetric.add.getCall(0).args[1].get(
+          'document_visible'), true);
+    });
+
+    it('does not record page load timing on other pages', () => {
+      mts.recordPageLoadTiming();
+      sinon.assert.notCalled(mts.pageLoadMetric.add);
+    });
+
+    it('does not record page load timing if over max threshold', () => {
+      window.performance = {
+        timing: {
+          navigationStart: 1000,
+          domContentLoadedEventEnd: 2001,
+        },
+      };
+      mts.recordIssueEntryTiming(1000);
+      sinon.assert.notCalled(mts.pageLoadMetric.add);
+    });
+
+    it('records page load on issue entry page if under threshold', () => {
+      MonorailTSMon.isPageVisible.restore();
+      sinon.stub(MonorailTSMon, 'isPageVisible').callsFake(() => (false));
+      window.performance = {
+        timing: {
+          navigationStart: 1000,
+          domContentLoadedEventEnd: 1999,
+        },
+      };
+      mts.recordIssueEntryTiming(1000);
+      sinon.assert.calledOnce(mts.pageLoadMetric.add);
+      assert.isNumber(mts.pageLoadMetric.add.getCall(0).args[0]);
+      assert.equal(mts.pageLoadMetric.add.getCall(0).args[0], 999);
+      assert.isString(mts.pageLoadMetric.add.getCall(0).args[1].get(
+          'client_id'));
+      assert.equal(mts.pageLoadMetric.add.getCall(0).args[1].get(
+          'host_name'), 'rutabaga-version');
+      assert.equal(mts.pageLoadMetric.add.getCall(0).args[1].get(
+          'template_name'), 'issue_entry');
+      assert.equal(mts.pageLoadMetric.add.getCall(0).args[1].get(
+          'document_visible'), false);
+    });
+  });
+
+  describe('getGlobalClient', () => {
+    it('only creates one global client', () => {
+      delete window.__tsMonClient;
+      const client1 = MonorailTSMon.getGlobalClient();
+      assert.equal(client1, window.__tsMonClient);
+
+      const client2 = MonorailTSMon.getGlobalClient();
+      assert.equal(client2, window.__tsMonClient);
+      assert.equal(client2, client1);
+    });
+  });
+});