Add test wrt #490, passing against 2.16 (#491)

ion/src/test/java/com/fasterxml/jackson/dataformat/ion/DatabindNumberRoundtrip490Test.java

@@ -0,0 +1,64 @@
+package com.fasterxml.jackson.dataformat.ion;
+
+import java.util.*;
+import org.junit.Test;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import static org.junit.Assert.*;
+
+// for [dataformats-binary#490]
+public class DatabindNumberRoundtrip490Test
+{
+    private final IonObjectMapper BINARY_MAPPER = IonObjectMapper.builderForBinaryWriters()
+            .build();
+    private final IonObjectMapper TEXT_MAPPER = IonObjectMapper.builderForTextualWriters()
+            .build();
+
+    @Test
+    public void testBinaryFloats() throws Exception {
+        _floatRoundtrip(BINARY_MAPPER);
+    }
+
+    @Test
+    public void testBinaryIntegers() throws Exception {
+        _integerRoundtrip490(BINARY_MAPPER);
+    }
+
+    @Test
+    public void testTextualFloats() throws Exception {
+        _floatRoundtrip(TEXT_MAPPER);
+    }
+
+    @Test
+    public void testTextualIntegers() throws Exception {
+        _integerRoundtrip490(TEXT_MAPPER);
+    }
+
+    private void _floatRoundtrip(ObjectMapper mapper) throws Exception
+    {
+        final double d = 42.25d;
+        final float f = 42.75f;
+
+        _roundtrip490(mapper, d, d);
+
+        // Ion oddity: "float"s get upgraded to "double"s, so...
+        _roundtrip490(mapper, f, (double) f);
+    }
+
+    private void _integerRoundtrip490(ObjectMapper mapper) throws Exception
+    {
+        _roundtrip490(mapper, Integer.MAX_VALUE, Integer.MAX_VALUE);
+        _roundtrip490(mapper, Long.MAX_VALUE, Long.MAX_VALUE);
+    }
+
+    private void _roundtrip490(ObjectMapper mapper,
+            Object input, Object result)
+        throws Exception
+    {
+        byte[] serialized = mapper.writeValueAsBytes(Collections.singletonMap("k", input));
+
+        Map<?,?> deserialized = mapper.readValue(serialized, Map.class);
+        assertEquals(result, deserialized.get("k"));
+    }
+}