Fix #3406: change default of DeserializationFeature.FAIL_ON_TRAILING_TOKENS to true

Author: cowtowncoder

release-notes/VERSION

@@ -62,6 +62,8 @@ Versions: 3.x (for earlier see VERSION-2.x)
 #3046: Rename `JsonSerializable` as `JacksonSerializable`
 #3047: Rename `Bean[De]SerializerModifier` as `Value[De]SerializerModifier`
 #3070: Change default for `SerializationFeature.FAIL_ON_EMPTY_BEANS` to `false`
+#3406: Change default of `DeserializationFeature.FAIL_ON_TRAILING_TOKENS` to `true` for 3.0
+ (suggested by @yawkat)
 #3522: Support serializing `ByteArrayOutputStream` as "simple" Binary value
 #3536: Create new exception type `JsonNodeException` for use by `JsonNode`-related problems
 #3542: Rename "com.fasterxml.jackson" -> "tools.jackson"

src/main/java/tools/jackson/databind/DeserializationFeature.java

@@ -247,10 +247,9 @@ public enum DeserializationFeature implements ConfigFeature
      * for binding the full value, and nothing more (except for possible ignorable
      * white space or comments, if supported by data format).
      *<p>
-     * Feature is disabled by default (so that no check is made for possible trailing
-     * token(s)) for backwards compatibility reasons.
+     * Feature is enabled by default as of Jackson 3.0 (in 2.x it was disabled).
      */
-    FAIL_ON_TRAILING_TOKENS(false),
+    FAIL_ON_TRAILING_TOKENS(true),
 
     /**
      * Feature that determines whether Jackson code should catch

src/test/java/tools/jackson/databind/node/TreeReadViaMapperTest.java

@@ -146,9 +146,11 @@ public void testNullViaParser() throws Exception
     @Test
     public void testMultiple() throws Exception
     {
-        final ObjectMapper mapper = objectMapper();
+        final ObjectMapper mapper = jsonMapperBuilder()
+                .disable(DeserializationFeature.FAIL_ON_TRAILING_TOKENS)
+                .build();
         String JSON = "12  \"string\" [ 1, 2, 3 ]";
-        JsonParser p = mapper.createParser(new StringReader(JSON));
+        JsonParser p = mapper.createParser(JSON);
         JsonNode result = mapper.readTree(p);
 
         assertTrue(result.isIntegralNumber());