diff --git a/static_src/shared/experiments.test.js b/static_src/shared/experiments.test.js
new file mode 100644
index 0000000..d5f96b7
--- /dev/null
+++ b/static_src/shared/experiments.test.js
@@ -0,0 +1,62 @@
+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import {assert} from 'chai';
+import {isExperimentEnabled, SLO_EXPERIMENT} from './experiments.js';
+
+
+describe('isExperimentEnabled', () => {
+  it('throws error for unknown experiment', () => {
+    assert.throws(() =>
+      isExperimentEnabled('unknown-exp', {displayName: 'jessan@google.com'}));
+  });
+
+  it('returns false if user not in experiment', () => {
+    const ineligibleUser = {displayName: 'example@example.com'};
+    assert.isFalse(isExperimentEnabled(SLO_EXPERIMENT, ineligibleUser, {}));
+  });
+
+  it('returns false if no user provided', () => {
+    assert.isFalse(isExperimentEnabled(SLO_EXPERIMENT, undefined, {}));
+  });
+
+  it('returns true if user in experiment', () => {
+    const eligibleUser = {displayName: 'jessan@google.com'};
+    assert.isTrue(isExperimentEnabled(SLO_EXPERIMENT, eligibleUser, {}));
+  });
+
+  it('is false if user in experiment has disabled it with URL', () => {
+    const eligibleUser = {displayName: 'jessan@google.com'};
+    assert.isFalse(isExperimentEnabled(
+        SLO_EXPERIMENT, eligibleUser, {'e': '-slo'}));
+  });
+
+  it('ignores enabling experiments with URL', () => {
+    const ineligibleUser = {displayName: 'example@example.com'};
+    assert.isFalse(isExperimentEnabled(
+        SLO_EXPERIMENT, ineligibleUser, {'e': 'slo'}));
+  });
+
+  it('ignores ineligible users disabling experiment with URL', () => {
+    const ineligibleUser = {displayName: 'example@example.com'};
+    assert.isFalse(isExperimentEnabled(
+        SLO_EXPERIMENT, ineligibleUser, {'e': '-slo'}));
+  });
+
+  it('ignores invalid experiments in URL', () => {
+    const eligibleUser = {displayName: 'jessan@google.com'};
+    // Leading comma, unknown experiment str, empty experiment str in
+    // middle, disable_str with no experiment, trailing comma
+    assert.isFalse(isExperimentEnabled(
+        SLO_EXPERIMENT, eligibleUser, {'e': ',unknown,-slo,,-,'}));
+  });
+
+  it('respects last instance when experiment repeated in URL', () => {
+    const eligibleUser = {displayName: 'jessan@google.com'};
+    assert.isFalse(isExperimentEnabled(
+        SLO_EXPERIMENT, eligibleUser, {'e': 'slo,-slo'}));
+    assert.isTrue(isExperimentEnabled(
+        SLO_EXPERIMENT, eligibleUser, {'e': '-slo,slo'}));
+  });
+});