Add a reproduction (failing unit test) for #471 (#472)

Author: cowtowncoder

ion/src/test/java/com/fasterxml/jackson/dataformat/ion/failing/IonFuzz_471_66141_AssertionErrorTest.java

@@ -0,0 +1,31 @@
+package com.fasterxml.jackson.dataformat.ion.failing;
+
+import org.hamcrest.Matchers;
+import org.junit.Test;
+
+import com.fasterxml.jackson.core.exc.StreamReadException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.dataformat.ion.*;
+import com.fasterxml.jackson.dataformat.ion.fuzz.IonFuzzTestUtil;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.Assert.fail;
+
+// [dataformats-binary#471]: AssertionError for corrupt Timestamp
+// https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=66141
+public class IonFuzz_471_66141_AssertionErrorTest
+{
+    private final ObjectMapper ION_MAPPER = new IonObjectMapper();
+
+    @Test
+    public void testFuzz66077_NegativeArraySize() throws Exception {
+        final byte[] doc = IonFuzzTestUtil.readResource("/data/fuzz-66141.ion");
+        try {
+            ION_MAPPER.readValue(doc, java.util.Date.class);
+            fail("Should not pass (invalid content)");
+        } catch (StreamReadException e) {
+            // May or may not be the exception message to get, change as appropriate
+            assertThat(e.getMessage(), Matchers.containsString("Corrupt content to decode"));
+        }
+    }
+}