Add more tests for FileReader.result. (#7494)

In particular this adds tests to verify the value of the attribute
during progress and loadstart events.

Author: mkruisselbrink

FileAPI/reading-data-section/filereader_events.any.js

@@ -0,0 +1,19 @@
+promise_test(async t => {
+  var reader = new FileReader();
+  var eventWatcher = new EventWatcher(t, reader, ['loadstart', 'progress', 'abort', 'error', 'load', 'loadend']);
+  reader.readAsText(new Blob([]));
+  await eventWatcher.wait_for('loadstart');
+  // No progress event for an empty blob, as no data is loaded.
+  await eventWatcher.wait_for('load');
+  await eventWatcher.wait_for('loadend');
+}, 'events are dispatched in the correct order for an empty blob');
+
+promise_test(async t => {
+  var reader = new FileReader();
+  var eventWatcher = new EventWatcher(t, reader, ['loadstart', 'progress', 'abort', 'error', 'load', 'loadend']);
+  reader.readAsText(new Blob(['a']));
+  await eventWatcher.wait_for('loadstart');
+  await eventWatcher.wait_for('progress');
+  await eventWatcher.wait_for('load');
+  await eventWatcher.wait_for('loadend');
+}, 'events are dispatched in the correct order for a non-empty blob');

FileAPI/reading-data-section/filereader_result.html

@@ -12,9 +12,10 @@
     <div id="log"></div>
 
     <script>
-    var blob;
+    var blob, blob2;
     setup(function() {
       blob = new Blob(["This test the result attribute"]);
+      blob2 = new Blob(["This is a second blob"]);
     });
 
     async_test(function() {
@@ -54,6 +55,43 @@
 
       readArrayBuffer.readAsArrayBuffer(blob);
     }, "readAsArrayBuffer");
+
+    async_test(function() {
+      var readBinaryString = new FileReader();
+      assert_equals(readBinaryString.result, null);
+
+      readBinaryString.onloadend = this.step_func(function(evt) {
+        assert_equals(typeof readBinaryString.result, "string", "The result type is string");
+        assert_equals(readBinaryString.result, "This test the result attribute", "The result is correct");
+        this.done();
+      });
+
+      readBinaryString.readAsBinaryString(blob);
+    }, "readAsBinaryString");
+
+
+    for (let event of ['loadstart', 'progress']) {
+      for (let method of ['readAsText', 'readAsDataURL', 'readAsArrayBuffer', 'readAsBinaryString']) {
+        promise_test(async function(t) {
+          var reader = new FileReader();
+          assert_equals(reader.result, null, 'result is null before read');
+
+          var eventWatcher = new EventWatcher(t, reader,
+              [event, 'loadend']);
+
+          reader[method](blob);
+          assert_equals(reader.result, null, 'result is null after first read call');
+          await eventWatcher.wait_for(event);
+          assert_equals(reader.result, null, 'result is null during event');
+          await eventWatcher.wait_for('loadend');
+          assert_not_equals(reader.result, null);
+          reader[method](blob);
+          assert_equals(reader.result, null, 'result is null after second read call');
+          await eventWatcher.wait_for(event);
+          assert_equals(reader.result, null, 'result is null during second read event');
+        }, 'result is null during "' + event + '" event for ' + method);
+      }
+    }
     </script>
   </body>
 </html>