3 files changed, 75 insertions, 0 deletions
diff --git a/dom/tests/mochitest/fetch/file_fetch_observer.html b/dom/tests/mochitest/fetch/file_fetch_observer.html
new file mode 100644
index 000000000..97af584ec
--- /dev/null
+++ b/dom/tests/mochitest/fetch/file_fetch_observer.html
@@ -0,0 +1,33 @@
+<script>
+function ok(a, msg) {
+  parent.postMessage({ type: "check", status: !!a, message: msg }, "*");
+}
+
+function is(a, b, msg) {
+  ok(a === b, msg);
+}
+
+function testObserver() {
+  ok("FetchObserver" in self, "We have a FetchObserver prototype");
+
+  fetch('data:,foo', { observe: o => {
+  }});
+}
+
+var steps = [
+  testObserver,
+];
+
+function next() {
+  if (!steps.length) {
+    parent.postMessage({ type: "finish" }, "*");
+    return;
+  }
+
+  var step = steps.shift();
+  step();
+}
+
+next();
+
+</script>
diff --git a/dom/tests/mochitest/fetch/mochitest.ini b/dom/tests/mochitest/fetch/mochitest.ini
index 6dba08f98..60fa454f4 100644
--- a/dom/tests/mochitest/fetch/mochitest.ini
+++ b/dom/tests/mochitest/fetch/mochitest.ini
@@ -5,6 +5,7 @@ support-files =
   test_fetch_basic.js
   test_fetch_basic_http.js
   test_fetch_cors.js
+  file_fetch_observer.html
   test_formdataparsing.js
   test_headers_common.js
   test_request.js
@@ -49,6 +50,7 @@ skip-if = toolkit == 'android' # Bug 1210282
 skip-if = toolkit == 'android' # Bug 1210282
 [test_fetch_cors_sw_empty_reroute.html]
 skip-if = toolkit == 'android' # Bug 1210282
+[test_fetch_observer.html] 
 [test_formdataparsing.html]
 [test_formdataparsing_sw_reroute.html]
 [test_request.html]
diff --git a/dom/tests/mochitest/fetch/test_fetch_observer.html b/dom/tests/mochitest/fetch/test_fetch_observer.html
new file mode 100644
index 000000000..2b6c0362d
--- /dev/null
+++ b/dom/tests/mochitest/fetch/test_fetch_observer.html
@@ -0,0 +1,40 @@
+<!--
+  Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test FetchObserver</title>
+  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<script class="testbody" type="text/javascript">
+
+SpecialPowers.pushPrefEnv({"set": [["dom.fetchObserver.enabled", true ]]}, () => {
+  let ifr = document.createElement('iframe');
+  ifr.src = "file_fetch_observer.html";
+  document.body.appendChild(ifr);
+
+  onmessage = function(e) {
+    if (e.data.type == "finish") {
+      SimpleTest.finish();
+      return;
+    }
+
+    if (e.data.type == "check") {
+      ok(e.data.status, e.data.message);
+      return;
+    }
+
+    ok(false, "Something when wrong.");
+  }
+});
+
+SimpleTest.waitForExplicitFinish();
+
+</script>
+</body>
+</html>
+