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+<!--
+  Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>File Handle Test</title>
+
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+
+  <script type="text/javascript">
+  async function testSteps() {
+    const name = window.location.pathname;
+
+    // Test setup begin
+    const fileHandle = await createReadWriteFileWithInitialContent(name, getBuffer(1));
+    // Test setup end
+
+    // Since TypeError is very generic, we also check the exception message.
+
+    // XXX If we add [EnforceRange] to IDBFileHandle.truncate, this will fail before truncate is called,
+    // and since UINT64_MAX is larger than Number.MAX_SAFE_INTEGER, we have no way to reliably test it,
+    // probably.
+
+    // XXX This restriction might go away once the use of UINT64_MAX as a special value is removed.
+    info("Expecting TypeError on truncating to a negative length that converts to UINT64_MAX implicitly");
+    let message = assertThrowsInstanceOf(() => { fileHandle.truncate(-1); }, TypeError);
+    is(message, "IDBFileHandle.truncate: UINT64_MAX is not a valid size", "Correct message");
+
+    info ("Attempt to truncate to a size larger than the current size should fail.");
+    // XXX Expect a more specific error here?
+    await expectingError(fileHandle.truncate(10000000), "UnknownError");
+
+    info("Still the state should be consistent and we should be able to truncate to a valid size after this.");
+    // This wasn't always the case, see Bug 1626973
+    await expectingSuccess(fileHandle.truncate(0));
+  }
+  </script>
+  <script type="text/javascript" src="file.js"></script>
+  <script type="text/javascript" src="helpers.js"></script>
+
+</head>
+
+<body onload="runTest();"></body>
+
+</html>