diff --git a/README.md b/README.md
index e2c79de..88e7e53 100644
--- a/README.md
+++ b/README.md
@@ -18,6 +18,14 @@ Please note that we are not taking external contributions for new test pages, bu
 - Please remember to link new test page from [index.html](./index.html).
 - Once you have a PR with a new page please assign it to one of the AoR DRIs (@brindy, @kdzwinel).
 
+### Test domains
+
+We have couple of test domains, that all resolve to `privacy-test-pages.glitch.me`, which help us simulate various scenarios:
+
+- `good.third-party.site` - non-tracking third party, it's not on our blocklist and will not be blocked by our clients
+- `broken.third-party.site` - tracking third party that we can't block (e.g. due to brekage), it's on our blocklist, but it will not be blocked by our clients
+- `bad.third-party.site` - tracking third party that's on our blocklist and our clients will block
+
 ### How to test it locally
 
 If you are working on a simple page you can start any local server (e.g. `python -m SimpleHTTPServer 8000`) in the main folder of the project.
diff --git a/privacy-protections/storage-blocking/3rdparty.js b/privacy-protections/storage-blocking/3rdparty.js
index 347f60d..abffe6e 100644
--- a/privacy-protections/storage-blocking/3rdparty.js
+++ b/privacy-protections/storage-blocking/3rdparty.js
@@ -4,12 +4,17 @@
  * As we load this script via a 3rd party origin in the test, when running `store` the 3rd party
  * origin will be visible in the call stack to document.cookie.
  */
-commonTests.push({
-    id: 'JS cookie (3rd party script)',
-    store: (data) => {
-        document.cookie = `tpdata=${data}; expires= Wed, 21 Aug 2030 20:00:00 UTC;`;
-    },
-    retrive: () => {
-        return document.cookie.match(/tpdata=([0-9]+)/)[1];
-    }
-});
+(function () {
+    const src = document.currentScript.src;
+    const trackingDomain = src.indexOf('https://broken.third-party.site/') === 0;
+
+    commonTests.push({
+        id: `JS cookie (3rd party ${trackingDomain ? 'tracking' : 'safe'} script)`,
+        store: (data) => {
+            document.cookie = `tp${trackingDomain ? 't' : 's'}data=${data}; expires= Wed, 21 Aug 2030 20:00:00 UTC;`;
+        },
+        retrive: () => {
+            return trackingDomain ? document.cookie.match(/tptdata=([0-9]+)/)[1] : document.cookie.match(/tpsdata=([0-9]+)/)[1];
+        }
+    });
+})();
diff --git a/privacy-protections/storage-blocking/index.html b/privacy-protections/storage-blocking/index.html
index f7e5b5a..d72e41e 100644
--- a/privacy-protections/storage-blocking/index.html
+++ b/privacy-protections/storage-blocking/index.html
@@ -7,6 +7,7 @@
 
     <script src='./helpers/idb-wrapper.js' defer></script>
     <script src='./helpers/commonTests.js'></script>
+    <script src='https://broken.third-party.site/privacy-protections/storage-blocking/3rdparty.js' defer></script>
     <script src='https://good.third-party.site/privacy-protections/storage-blocking/3rdparty.js' defer></script>
     <script src='./main.js' defer></script>
     <link href='./style.css' rel='stylesheet'></link>
@@ -27,4 +28,4 @@
     <p><button id='download' disabled>Download the result</button></p>
 
 </body>
-</html>
\ No newline at end of file
+</html>
diff --git a/privacy-protections/storage-blocking/main.js b/privacy-protections/storage-blocking/main.js
index 42eabec..4092d13 100644
--- a/privacy-protections/storage-blocking/main.js
+++ b/privacy-protections/storage-blocking/main.js
@@ -1,5 +1,6 @@
 /* globals commonTests */
 const THIRD_PARTY_ORIGIN = 'https://good.third-party.site';
+const THIRD_PARTY_TRACKER_ORIGIN = 'https://broken.third-party.site';
 
 const storeButton = document.querySelector('#store');
 const retriveButton = document.querySelector('#retrive');
@@ -16,51 +17,21 @@ const results = {
     results: []
 };
 
-const tests = [
-    {
-        id: 'header cookie',
-        store: (data) => {
-            return fetch(`/set-cookie?value=${data}`).then(r => {
-                if (!r.ok) {
-                    throw new Error('Request failed.');
-                }
-            });
-        },
-        retrive: () => {
-            return fetch('/reflect-headers')
-                .then(r => r.json())
-                .then(data => data.headers.cookie.match(/headerdata=([0-9]+)/)[1]);
-        }
-    },
-    {
-        id: 'third party header cookie',
-        store: (data) => {
-            return fetch(`${THIRD_PARTY_ORIGIN}/set-cookie?value=${data}`, { credentials: 'include' }).then(r => {
-                if (!r.ok) {
-                    throw new Error('Request failed.');
-                }
-            });
-        },
-        retrive: () => {
-            return fetch(`${THIRD_PARTY_ORIGIN}/reflect-headers`, { credentials: 'include' })
-                .then(r => r.json())
-                .then(data => data.headers.cookie.match(/headerdata=([0-9]+)/)[1]);
-        }
-    },
-    {
-        id: 'third party iframe',
+function create3pIframeTest (name, origin) {
+    return {
+        id: `${name} third party iframe`,
         store: (data) => {
             let res, rej;
             const promise = new Promise((resolve, reject) => { res = resolve; rej = reject; });
 
             const iframe = document.createElement('iframe');
-            iframe.src = `${THIRD_PARTY_ORIGIN}/privacy-protections/storage-blocking/iframe.html?data=${data}`;
+            iframe.src = `${origin}/privacy-protections/storage-blocking/iframe.html?data=${data}`;
             iframe.style.width = '10px';
             iframe.style.height = '10px';
             let failTimeout = null;
 
             function cleanUp (msg) {
-                if (msg.data) {
+                if (msg.origin === origin && msg.data) {
                     res(msg.data);
 
                     clearTimeout(failTimeout);
@@ -83,7 +54,7 @@ const tests = [
             const promise = new Promise((resolve, reject) => { res = resolve; rej = reject; });
 
             const iframe = document.createElement('iframe');
-            iframe.src = `${THIRD_PARTY_ORIGIN}/privacy-protections/storage-blocking/iframe.html`;
+            iframe.src = `${origin}/privacy-protections/storage-blocking/iframe.html`;
             iframe.style.width = '10px';
             iframe.style.height = '10px';
             let failTimeout = null;
@@ -107,7 +78,57 @@ const tests = [
 
             return promise;
         }
+    };
+}
+
+const tests = [
+    {
+        id: 'first party header cookie',
+        store: (data) => {
+            return fetch(`/set-cookie?value=${data}`).then(r => {
+                if (!r.ok) {
+                    throw new Error('Request failed.');
+                }
+            });
+        },
+        retrive: () => {
+            return fetch('/reflect-headers')
+                .then(r => r.json())
+                .then(data => data.headers.cookie.match(/headerdata=([0-9]+)/)[1]);
+        }
+    },
+    {
+        id: 'safe third party header cookie',
+        store: (data) => {
+            return fetch(`${THIRD_PARTY_ORIGIN}/set-cookie?value=${data}`, { credentials: 'include' }).then(r => {
+                if (!r.ok) {
+                    throw new Error('Request failed.');
+                }
+            });
+        },
+        retrive: () => {
+            return fetch(`${THIRD_PARTY_ORIGIN}/reflect-headers`, { credentials: 'include' })
+                .then(r => r.json())
+                .then(data => data.headers.cookie.match(/headerdata=([0-9]+)/)[1]);
+        }
+    },
+    {
+        id: 'tracking third party header cookie',
+        store: (data) => {
+            return fetch(`${THIRD_PARTY_TRACKER_ORIGIN}/set-cookie?value=${data}`, { credentials: 'include' }).then(r => {
+                if (!r.ok) {
+                    throw new Error('Request failed.');
+                }
+            });
+        },
+        retrive: () => {
+            return fetch(`${THIRD_PARTY_TRACKER_ORIGIN}/reflect-headers`, { credentials: 'include' })
+                .then(r => r.json())
+                .then(data => data.headers.cookie.match(/headerdata=([0-9]+)/)[1]);
+        }
     },
+    create3pIframeTest('safe', THIRD_PARTY_ORIGIN),
+    create3pIframeTest('tracking', THIRD_PARTY_TRACKER_ORIGIN),
     {
         id: 'browser cache',
         store: (data) => {