Fix #359 by removing "String null coercion" setting, fixing tests

Author: cowtowncoder

src/main/java/tools/jackson/dataformat/xml/XmlMapper.java

@@ -6,9 +6,7 @@
 import javax.xml.stream.XMLStreamReader;
 import javax.xml.stream.XMLStreamWriter;
 
-import com.fasterxml.jackson.annotation.JsonSetter;
 import com.fasterxml.jackson.annotation.JsonTypeInfo;
-import com.fasterxml.jackson.annotation.Nulls;
 
 import tools.jackson.core.*;
 import tools.jackson.core.type.TypeReference;
@@ -83,8 +81,10 @@ public Builder(XmlFactory f) {
             //   to empty string -- this lets us induce `null` from empty tags firs
             // 08-Sep-2019, tatu: This causes [dataformat-xml#359] (follow-up for #354), but
             //    can not simply be removed.
-            _configOverrides.findOrCreateOverride(String.class)
-                .setNullHandling(JsonSetter.Value.forValueNulls(Nulls.AS_EMPTY));
+            // 19-Mar-2023, tatu: Nah. Let's not coerce to let `xsi:nil` works its magic
+
+            //_configOverrides.findOrCreateOverride(String.class)
+            //    .setNullHandling(JsonSetter.Value.forValueNulls(Nulls.AS_EMPTY));
 
             // 13-May-2020, tatu: [dataformat-xml#377] Need to ensure we will keep XML-specific
             //    Base64 default as "MIME" (not MIME-NO-LINEFEEDS), to preserve pre-2.12

src/main/java/tools/jackson/dataformat/xml/deser/FromXmlParser.java

@@ -1,7 +1,6 @@
 package tools.jackson.dataformat.xml.deser;
 
 import java.io.IOException;
-import java.io.UncheckedIOException;
 import java.io.Writer;
 import java.math.BigDecimal;
 import java.math.BigInteger;

src/test/java/tools/jackson/dataformat/xml/deser/NullConversionsSkipTest.java

@@ -58,7 +58,7 @@ public void testSkipNullField1() throws Exception
 "<NullSkipField><noNulls>foo</noNulls><nullsOk /></NullSkipField>",
                 NullSkipField.class);
         assertEquals("foo", result.noNulls);
-        assertEquals("", result.nullsOk);
+        assertNull(result.nullsOk);
     }
 
     public void testSkipNullField2() throws Exception
@@ -77,7 +77,7 @@ public void testSkipNullMethod1() throws Exception
 "<NullSkipMethod><noNulls>foo</noNulls><nullsOk /></NullSkipMethod>",
                 NullSkipMethod.class);
         assertEquals("foo", result._noNulls);
-        assertEquals("", result._nullsOk);
+        assertNull(result._nullsOk);
     }
 
     public void testSkipNullMethod2() throws Exception
@@ -99,7 +99,7 @@ public void testSkipNullWithDefaults() throws Exception
 //        String doc = "<StringValue><value></value></StringValue>";
         String doc = "<StringValue><value /></StringValue>";
         StringValue result = NULL_EXPOSING_MAPPER.readValue(doc, StringValue.class);
-        assertEquals("", result.value);
+        assertNull(result.value);
 
         ObjectMapper mapper = mapperBuilder()
                 .enable(FromXmlParser.Feature.EMPTY_ELEMENT_AS_NULL)

src/test/java/tools/jackson/dataformat/xml/deser/XsiNilForStringsTest.java

@@ -13,11 +13,6 @@ protected static class StringPair {
 
     private final XmlMapper MAPPER = newMapper();
 
-    // 04-Jan-2019, tatu: Due to default "Map Strings to Null values" coercion (see XmlMapper),
-    //    tests for `null` handling are not quite right for 3.x... ideally would probably
-    //    NOT use coercion, maybe, or (if possible) avoid doing that for `xsi:nil` induced
-    //    reliable one. But as of now not 100% clear how this could be done so comment out tests
-    
     // [dataformat-xml#378]
     public void testWithStringAsNull() throws Exception
     {
@@ -30,9 +25,7 @@ public void testWithStringAsNull() throws Exception
 
         assertEquals("not null", bean.first);
 
-        // for 3.0:
-//        assertNull(bean.second);
-        assertEquals("", bean.second);
+        assertNull(bean.second);
     }
 
     // [dataformat-xml#378]
@@ -47,8 +40,6 @@ public void testWithStringAsNull2() throws Exception
         assertNotNull(bean);
         assertEquals("not null", bean.second);
 
-        // for 3.0:
-//      assertNull(bean.first);
-      assertEquals("", bean.first);
+      assertNull(bean.first);
     }
 }

src/test/java/tools/jackson/dataformat/xml/lists/StringListRoundtripTest.java

@@ -264,11 +264,7 @@ public void testStringPojo() throws Exception
 		_stringPojoRoundtrip(MAPPER_READ_NULLS, false);
 
 		// xsi null enabled, should get back null
-
-		// 19-Mar-2023, tatu: I think this fails due to [dataformat-xml#359]:
-		//   need to comment out for now
-
-//		_stringPojoRoundtrip(MAPPER_READ_WRITE_NULLS, true);
+		_stringPojoRoundtrip(MAPPER_READ_WRITE_NULLS, true);
 
 		// xsi null write enabled but processing disabled, should get back empty string
 		_stringPojoRoundtrip(MAPPER_WRITE_NULLS, false);