Fix xml toString() error for modified name space attributes

bvm/ballerina-runtime/src/main/java/io/ballerina/runtime/internal/BallerinaXmlSerializer.java

@@ -287,7 +287,7 @@ private String getXmlNsUriPrefix(Map<String, String> nsPrefixMap, String uri) {
     }
 
     private void writeAttributes(HashSet<String> curNSSet, Map<String, String> attributeMap) throws XMLStreamException {
-        String defaultNS = xmlStreamWriter.getNamespaceContext().getNamespaceURI(XMLNS);
+        String defaultNS = xmlStreamWriter.getNamespaceContext().getNamespaceURI("");
         for (Map.Entry<String, String> attributeEntry : attributeMap.entrySet()) {
             String key = attributeEntry.getKey();
             int closingCurlyPos = key.lastIndexOf('}');

tests/jballerina-unit-test/src/test/java/org/ballerinalang/test/types/xml/XMLLiteralWithNamespacesTest.java

@@ -31,6 +31,7 @@
 import org.testng.Assert;
 import org.testng.annotations.AfterClass;
 import org.testng.annotations.BeforeClass;
+import org.testng.annotations.DataProvider;
 import org.testng.annotations.Test;
 
 import java.io.ByteArrayOutputStream;
@@ -178,7 +179,7 @@ public void testObjectLevelXML() {
     public void xmlWithDefaultNamespaceToString() {
         Object returns = BRunUtil.invoke(literalWithNamespacesResult, "XMLWithDefaultNamespaceToString");
         Assert.assertEquals(returns.toString(),
-                "<Order xmlns=\"http://acme.company\" xmlns:acme=\"http://acme.company\">\n" +
+                "<Order xmlns=\"http://acme.company\" xmlns:acme=\"http://acme.company.nondefault\">\n" +
                         "        <OrderLines>\n" +
                         "            <OrderLine acme:lineNo=\"334\" itemCode=\"334-2\"/>\n" +
                         "        </OrderLines>\n" +
@@ -199,21 +200,25 @@ public void testXMLSerialize() {
                 "<foo xmlns=\"http://wso2.com/\">hello</foo>");
     }
 
-    @Test
-    public void testXmlLiteralUsingXmlNamespacePrefix() {
-        BRunUtil.invoke(literalWithNamespacesResult, "testXmlLiteralUsingXmlNamespacePrefix");
-    }
-
     @Test
     public void testXMLToString() {
         BXml xml = XmlFactory.parse("<?xml version=\"1.0\" encoding=\"UTF-8\"?>" +
                 "<!DOCTYPE foo [<!ELEMENT foo ANY ><!ENTITY data \"Example\" >]><foo>&data;</foo>");
         Assert.assertEquals(xml.toString(), "<foo>Example</foo>");
     }
 
-    @Test
-    public void testXmlInterpolationWithQuery() {
-        BRunUtil.invoke(literalWithNamespacesResult, "testXmlInterpolationWithQuery");
+    @Test (dataProvider = "xmlValueFunctions")
+    public void testXmlStrings(String functionName) {
+        BRunUtil.invoke(literalWithNamespacesResult, functionName);
+    }
+
+    @DataProvider(name = "xmlValueFunctions")
+    private String[] xmlValueFunctions() {
+        return new String[]{
+                "testXmlLiteralUsingXmlNamespacePrefix",
+                "testXmlInterpolationWithQuery",
+                "testAddAttributeToDefaultNS"
+        };
     }
 
     @AfterClass

tests/jballerina-unit-test/src/test/resources/test-src/types/xml/xml-literals-with-namespaces.bal

@@ -147,7 +147,7 @@ function getXML() returns xml {
 }
 
 function XMLWithDefaultNamespaceToString() returns string {
-    xml x = xml `<Order xmlns="http://acme.company" xmlns:acme="http://acme.company">
+    xml x = xml `<Order xmlns="http://acme.company" xmlns:acme="http://acme.company.nondefault">
         <OrderLines>
             <OrderLine acme:lineNo="334" itemCode="334-2"></OrderLine>
         </OrderLines>
@@ -294,3 +294,21 @@ function testXmlInterpolationWithQuery() returns error? {
         }
     }
 }
+
+function testAddAttributeToDefaultNS() {
+    xml x1 = xml `<root xmlns="http://sample.com/wso2/c1" xmlns:ns3="http://sample.com/wso2/f"></root>`;
+    var xAttr = let var x2 = <'xml:Element>x1 in x2.getAttributes();
+    //adding attribute with default namespace
+    xAttr["{http://sample.com/wso2/c1}foo1"] = "bar1";
+    string s = x1.toString();
+    string expectedStr = "<root xmlns=\"http://sample.com/wso2/c1\" xmlns:ns3=\"http://sample.com/wso2/f\" foo1=\"bar1\"/>";
+    if (s != expectedStr) {
+        panic error("Assertion error", expected = expectedStr, found=s);
+    }
+    s = xAttr.toString();
+    expectedStr = "{\"{http://www.w3.org/2000/xmlns/}xmlns\":\"http://sample.com/wso2/c1\"," +
+    "\"{http://www.w3.org/2000/xmlns/}ns3\":\"http://sample.com/wso2/f\",\"{http://sample.com/wso2/c1}foo1\":\"bar1\"}";
+        if (s != expectedStr) {
+        panic error("Assertion error", expected = expectedStr, found=s);
+    }
+}