Adds simple test for OnionPerf schema v3.1

This test only ensures that the new fields do
not cause the parser to crash, it does not look
at actually parsing those fields.

Fixes: #40003

src/test/java/org/torproject/descriptor/onionperf/OnionPerfAnalysisConverterTest.java

@@ -180,5 +180,24 @@ public class OnionPerfAnalysisConverterTest {
     }
     assertTrue(expectedTorperfResults.isEmpty());
   }
-}
 
+  @Test
+  public void testDoesNotCrashVersion31() throws IOException,
+          DescriptorParseException {
+    URL resouce = getClass().getClassLoader().getResource(
+            "onionperf/v3.1.onionperf.analysis.json.xz");
+    assertNotNull(resouce);
+    InputStream compressedInputStream = resouce.openStream();
+    assertNotNull(compressedInputStream);
+    byte[] rawDescriptorBytes = IOUtils.toByteArray(compressedInputStream);
+    OnionPerfAnalysisConverter onionPerfAnalysisConverter
+            = new OnionPerfAnalysisConverter(rawDescriptorBytes, null);
+    for (Descriptor descriptor
+            : onionPerfAnalysisConverter.asTorperfResults()) {
+      assertTrue(descriptor instanceof TorperfResult);
+      String formattedTorperfResult
+              = new String(descriptor.getRawDescriptorBytes()).trim();
+      assertNotNull(formattedTorperfResult);
+    }
+  }
+}
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