--- a/testing/web-platform/meta/MANIFEST.json
+++ b/testing/web-platform/meta/MANIFEST.json
@@ -287196,16 +287196,21 @@
      {}
     ]
    ],
    "interfaces/html.idl": [
     [
      {}
     ]
    ],
+   "interfaces/input-events.idl": [
+    [
+     {}
+    ]
+   ],
    "interfaces/keyboard-lock.idl": [
     [
      {}
     ]
    ],
    "interfaces/keyboard-map.idl": [
     [
      {}
@@ -580929,17 +580934,17 @@
    "c11d6b875af47f6134c98a23a7d2ce4fe4baa8c2",
    "wdspec"
   ],
   "input-events/OWNERS": [
    "9e7b0206de5d60e7e0cf529e7b8987367c84c0f6",
    "support"
   ],
   "input-events/idlharness.html": [
-   "cd25518dd402033694667ccd1982fd3b85faa412",
+   "51c7e4864c9ec4ce110cacbfc4cad2114f5eae01",
    "testharness"
   ],
   "input-events/input-events-cut-paste-manual.html": [
    "442b82811d9fabc1cd4b398ac28cac58d4f2f78b",
    "manual"
   ],
   "input-events/input-events-exec-command.html": [
    "233270068ad21c786fed0603a522d286c2419d56",
@@ -581088,16 +581093,20 @@
   "interfaces/hr-time.idl": [
    "db4f313176e4fdfb8efd78545079da42cbb0729b",
    "support"
   ],
   "interfaces/html.idl": [
    "fe86c7370a537be87884d1b9da1f7b7630c6af41",
    "support"
   ],
+  "interfaces/input-events.idl": [
+   "99bcfa971e6b2628ab8ba174b772d56b23dee38b",
+   "support"
+  ],
   "interfaces/keyboard-lock.idl": [
    "7188a9233db3acc741650d46156e16e9e7a132fa",
    "support"
   ],
   "interfaces/keyboard-map.idl": [
    "1e9e311a4d347d9f036702d29ef0bc82fca04162",
    "support"
   ],

--- a/testing/web-platform/tests/input-events/idlharness.html
+++ b/testing/web-platform/tests/input-events/idlharness.html
@@ -1,38 +1,29 @@
 <title>Input Event IDL tests</title>
 <link rel="help" href="https://w3c.github.io/input-events/#h-interface-inputevent"/>
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
 <script src="/resources/WebIDLParser.js"></script>
 <script src="/resources/idlharness.js"></script>
-
-<pre id="untested_idl">
-interface InputEvent {
-};
-</pre>
-
-<pre id='idl'>
-partial interface InputEvent {
-    readonly attribute DOMString     inputType;
-    readonly attribute DataTransfer? dataTransfer;
-    sequence<StaticRange> getTargetRanges();
-};
+<script>
+"use strict";
 
-partial dictionary InputEventInit {
-    DOMString             inputType = "";
-    DataTransfer?         dataTransfer = null;
-    sequence<StaticRange> targetRanges = [];
-};
-</pre>
-
-<script>
-(function(){
-    "use strict";
+function doTest([input_events]) {
     const idl_array = new IdlArray();
-    idl_array.add_untested_idls(document.getElementById("untested_idl").textContent);
-    idl_array.add_idls(document.getElementById("idl").textContent);
+    idl_array.add_untested_idls('interface InputEvent {};');
+    idl_array.add_untested_idls('dictionary InputEventInit {};');
+    idl_array.add_idls(input_events);
     idl_array.add_objects({
-      InputEvent: ['new InputEvent("foo")'],
+        InputEvent: ['new InputEvent("foo")'],
     });
     idl_array.test();
-})();
+}
+
+function fetchText(url) {
+    return fetch(url).then((response) => response.text());
+}
+
+promise_test(() => {
+    return Promise.all(["/interfaces/input-events.idl"].map(fetchText))
+                  .then(doTest);
+}, "Test IDL implementation of Input Events");
 </script>

new file mode 100644
--- /dev/null
+++ b/testing/web-platform/tests/interfaces/input-events.idl
@@ -0,0 +1,11 @@
+partial interface InputEvent {
+  readonly attribute DOMString inputType;
+  readonly attribute DataTransfer? dataTransfer;
+  sequence<StaticRange> getTargetRanges();
+};
+
+partial dictionary InputEventInit {
+  DOMString inputType = "";
+  DataTransfer? dataTransfer = null;
+  sequence<StaticRange> targetRanges = [];
+};