diff --git a/xpcom/tests/gtest/TestSeekableStreamWrapper.cpp b/xpcom/tests/gtest/TestSeekableStreamWrapper.cpp
new file mode 100644
index 000000000000..a9d1c454cf4e
--- /dev/null
+++ b/xpcom/tests/gtest/TestSeekableStreamWrapper.cpp
@@ -0,0 +1,200 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdlib.h>
+#include "gtest/gtest.h"
+#include "Helpers.h"
+#include "mozilla/SeekableStreamWrapper.h"
+#include "nsIPipe.h"
+
+static void NewSeekablePipe(nsIInputStream** aReader,
+                            nsIOutputStream** aWriter) {
+  nsCOMPtr<nsIAsyncInputStream> reader;
+  nsCOMPtr<nsIAsyncOutputStream> writer;
+
+  nsresult rv =
+      NS_NewPipe2(getter_AddRefs(reader), getter_AddRefs(writer), true, true);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsCOMPtr<nsISeekableStream> seekable = do_QueryInterface(reader);
+  EXPECT_FALSE(seekable);
+
+  nsCOMPtr<nsIInputStream> wrapped;
+  rv = mozilla::SeekableStreamWrapper::MaybeWrap(do_AddRef(reader),
+                                                 getter_AddRefs(wrapped));
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  wrapped.forget(aReader);
+  writer.forget(aWriter);
+}
+
+TEST(SeekableStreamWrapper, NoWrap)
+{
+  nsTArray<char> inputData;
+  testing::CreateData(4096, inputData);
+  nsDependentCSubstring inputString(inputData.Elements(), inputData.Length());
+
+  nsCOMPtr<nsIInputStream> stream;
+  nsresult rv = NS_NewCStringInputStream(getter_AddRefs(stream), inputString);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsCOMPtr<nsIInputStream> wrapped;
+  rv = mozilla::SeekableStreamWrapper::MaybeWrap(do_AddRef(stream),
+                                                 getter_AddRefs(wrapped));
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  EXPECT_EQ(stream, wrapped);
+
+  testing::ConsumeAndValidateStream(wrapped, inputString);
+}
+
+TEST(SeekableStreamWrapper, WrapPipe)
+{
+  nsCOMPtr<nsIInputStream> reader;
+  nsCOMPtr<nsIOutputStream> writer;
+
+  NewSeekablePipe(getter_AddRefs(reader), getter_AddRefs(writer));
+
+  nsTArray<char> inputData;
+  testing::CreateData(1024, inputData);
+
+  uint32_t numWritten = 0;
+  nsresult rv =
+      writer->Write(inputData.Elements(), inputData.Length(), &numWritten);
+  EXPECT_TRUE(NS_SUCCEEDED(rv));
+  EXPECT_EQ(numWritten, 1024u);
+
+  nsCOMPtr<nsISeekableStream> seekable = do_QueryInterface(reader);
+  ASSERT_TRUE(seekable);
+
+  nsCOMPtr<nsICloneableInputStream> cloneable = do_QueryInterface(reader);
+  ASSERT_TRUE(cloneable);
+  ASSERT_TRUE(cloneable->GetCloneable());
+
+  nsCOMPtr<nsIInputStream> clone1;
+  rv = cloneable->Clone(getter_AddRefs(clone1));
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+  ASSERT_TRUE(clone1);
+
+  // Check that we can read the first 512 bytes.
+  {
+    char buf[512];
+    uint32_t numRead = 0;
+    rv = reader->Read(buf, 512, &numRead);
+    EXPECT_TRUE(NS_SUCCEEDED(rv));
+    EXPECT_EQ(numRead, 512u);
+    EXPECT_EQ(mozilla::Span(inputData).First(512), mozilla::Span(buf));
+  }
+
+  // Check that we can read the second 512 bytes.
+  {
+    char buf[512];
+    uint32_t numRead = 0;
+    rv = reader->Read(buf, 512, &numRead);
+    EXPECT_TRUE(NS_SUCCEEDED(rv));
+    EXPECT_EQ(numRead, 512u);
+    EXPECT_EQ(mozilla::Span(inputData).Last(512), mozilla::Span(buf));
+  }
+
+  // Should be at the end of the pipe
+  {
+    char buf[1];
+    uint32_t numRead = 0;
+    rv = reader->Read(buf, 1, &numRead);
+    EXPECT_EQ(rv, NS_BASE_STREAM_WOULD_BLOCK);
+  }
+
+  // Re-read the second 512 bytes by seeking back.
+  {
+    rv = seekable->Seek(nsISeekableStream::NS_SEEK_CUR, -512);
+    EXPECT_TRUE(NS_SUCCEEDED(rv));
+
+    char buf[512];
+    uint32_t numRead = 0;
+    rv = reader->Read(buf, 512, &numRead);
+    EXPECT_TRUE(NS_SUCCEEDED(rv));
+    EXPECT_EQ(numRead, 512u);
+    EXPECT_EQ(mozilla::Span(inputData).Last(512), mozilla::Span(buf));
+  }
+
+  // Re-read the last 256 bytes by seeking absolutely
+  {
+    rv = seekable->Seek(nsISeekableStream::NS_SEEK_SET, 768);
+    EXPECT_TRUE(NS_SUCCEEDED(rv));
+
+    char buf[256];
+    uint32_t numRead = 0;
+    rv = reader->Read(buf, 256, &numRead);
+    EXPECT_TRUE(NS_SUCCEEDED(rv));
+    EXPECT_EQ(numRead, 256u);
+    EXPECT_EQ(mozilla::Span(inputData).Last(256), mozilla::Span(buf));
+  }
+
+  // Double-check that we haven't impacted our clone
+  {
+    char buf[1024];
+    uint32_t numRead = 0;
+    rv = clone1->Read(buf, 1024, &numRead);
+    EXPECT_TRUE(NS_SUCCEEDED(rv));
+    EXPECT_EQ(numRead, 1024u);
+    EXPECT_EQ(mozilla::Span(inputData), mozilla::Span(buf));
+  }
+
+  // The clone should no longer be seekable once closed.
+  rv = clone1->Close();
+  EXPECT_TRUE(NS_SUCCEEDED(rv));
+  nsCOMPtr<nsISeekableStream> clone1Seekable(do_QueryInterface(clone1));
+  rv = clone1Seekable->Seek(nsISeekableStream::NS_SEEK_SET, 0);
+  EXPECT_TRUE(NS_FAILED(rv));
+
+  // Should still be open
+  {
+    uint64_t available = 0;
+    rv = reader->Available(&available);
+    EXPECT_TRUE(NS_SUCCEEDED(rv));
+    EXPECT_EQ(available, uint64_t(0));
+  }
+
+  // Close the original output stream
+  rv = writer->Close();
+  EXPECT_TRUE(NS_SUCCEEDED(rv));
+
+  // Should be closed
+  {
+    uint64_t available = 0;
+    rv = reader->Available(&available);
+    EXPECT_EQ(rv, NS_BASE_STREAM_CLOSED);
+  }
+
+  // Seeing back to the beginning should re-open the stream which had reached
+  // the end.
+  rv = seekable->Seek(nsISeekableStream::NS_SEEK_SET, 0);
+  EXPECT_TRUE(NS_SUCCEEDED(rv));
+  testing::ConsumeAndValidateStream(reader, inputData);
+}
+
+TEST(SeekableStreamWrapper, Interfaces)
+{
+  nsCOMPtr<nsIInputStream> reader;
+  nsCOMPtr<nsIOutputStream> writer;
+
+  NewSeekablePipe(getter_AddRefs(reader), getter_AddRefs(writer));
+
+  nsCOMPtr<nsIAsyncInputStream> readerType1 = do_QueryInterface(reader);
+  EXPECT_TRUE(readerType1);
+
+  nsCOMPtr<nsITellableStream> readerType2 = do_QueryInterface(reader);
+  EXPECT_TRUE(readerType2);
+
+  nsCOMPtr<nsISeekableStream> readerType3 = do_QueryInterface(reader);
+  EXPECT_TRUE(readerType3);
+
+  nsCOMPtr<nsICloneableInputStream> readerType4 = do_QueryInterface(reader);
+  EXPECT_TRUE(readerType4);
+
+  nsCOMPtr<nsIBufferedInputStream> readerType5 = do_QueryInterface(reader);
+  EXPECT_TRUE(readerType5);
+}
diff --git a/xpcom/tests/gtest/moz.build b/xpcom/tests/gtest/moz.build
index 0b9223a940c2..a0c9187d7089 100644
--- a/xpcom/tests/gtest/moz.build
+++ b/xpcom/tests/gtest/moz.build
@@ -40,6 +40,7 @@ UNIFIED_SOURCES += [
     "TestRacingServiceManager.cpp",
     "TestRecursiveMutex.cpp",
     "TestRWLock.cpp",
+    "TestSeekableStreamWrapper.cpp",
     "TestSegmentedBuffer.cpp",
     "TestSlicedInputStream.cpp",
     "TestSmallArrayLRUCache.cpp",