Add failing tests for #428

ion/src/test/java/com/fasterxml/jackson/dataformat/ion/failing/IonNumberOverflow428Test.java

@@ -0,0 +1,76 @@
+package com.fasterxml.jackson.dataformat.ion.failing;
+
+import org.hamcrest.Matchers;
+import org.junit.Test;
+
+import com.fasterxml.jackson.core.exc.InputCoercionException;
+import com.fasterxml.jackson.dataformat.ion.*;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+
+import java.math.BigInteger;
+
+// for [dataformats-ion#428]
+public class IonNumberOverflow428Test
+{
+    private final IonObjectMapper MAPPER = IonObjectMapper
+            .builderForBinaryWriters()
+            .build();
+
+    // Test to ensure we handle value overflow (long->int) correctly
+    @Test
+    public void testIntCoercionOverflow() throws Exception {
+        _testIntCoercionFail(Long.valueOf(3L * Integer.MAX_VALUE / 2L));
+    }
+
+    @Test
+    public void testIntCoercionUnderflow() throws Exception {
+        _testIntCoercionFail(Long.valueOf(3L * Integer.MIN_VALUE / 2L));
+    }
+
+    private void _testIntCoercionFail(Long input) throws Exception
+    {
+        final byte[] doc = MAPPER.writeValueAsBytes(input);
+
+        // First, verify correct value decoding
+        assertEquals(input, MAPPER.readValue(doc, Long.class));
+
+        // And then over/underflow
+        try {
+            Integer result = MAPPER.readValue(doc, Integer.class);
+            fail("Should not pass; got: "+result+" (from "+input+")");
+        } catch (InputCoercionException e) {
+            assertThat(e.getMessage(), Matchers.containsString("out of range of int"));
+        }
+    }
+
+    // Test to ensure we handle value overflow (BigInteger->long) correctly
+    @Test
+    public void testLongCoercionOverflow() throws Exception {
+        _testLongCoercionFail(BigInteger.valueOf(Long.MAX_VALUE).add(BigInteger.TEN));
+    }
+
+    @Test
+    public void testLongCoercionUnderflow() throws Exception {
+        _testLongCoercionFail(BigInteger.valueOf(Long.MIN_VALUE).subtract(BigInteger.TEN));
+    }
+
+    private void _testLongCoercionFail(BigInteger input) throws Exception
+    {
+        final byte[] doc = MAPPER.writeValueAsBytes(input);
+
+        // First, verify correct value decoding
+        assertEquals(input, MAPPER.readValue(doc, BigInteger.class));
+
+        // And then over/underflow
+        try {
+            Long result = MAPPER.readValue(doc, Long.class);
+            fail("Should not pass; got: "+result+" (from "+input+")");
+        } catch (InputCoercionException e) {
+            assertThat(e.getMessage(), Matchers.containsString("out of range of long"));
+        }
+    }
+
+}

ion/src/test/java/com/fasterxml/jackson/dataformat/ion/fuzz/Fuzz_65062_VarintTest.java

@@ -17,7 +17,7 @@
 // https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=65062
 public class Fuzz_65062_VarintTest
 {
-    final IonObjectMapper MAPPER = IonObjectMapper.builder().build();
+    private final IonObjectMapper MAPPER = IonObjectMapper.builder().build();
 
     @Test
     public void testFuzz65062_Varint() throws Exception {