Accept prefixed xml attributes with null value

This changes makes PrefixedAttribute work the same way as
UnprefixedAttribute with respect to null values:

<t p:a={ null: String }/> is accepted and results in <t/>

1 files changed, 22 insertions, 3 deletions

diff --git a/test/files/run/xml-attribute.scala b/test/files/run/xml-attribute.scala
index 2b83f70b22..8b261acc94 100644
--- a/test/files/run/xml-attribute.scala
+++ b/test/files/run/xml-attribute.scala
@@ -5,10 +5,29 @@ object Test {
     val noAttr = <t/>
     val attrNull = <t a={ null: String }/>
     val attrNone = <t a={ None: Option[Seq[Node]] }/>
+    val preAttrNull = <t p:a={ null: String }/>
+    val preAttrNone = <t p:a={ None: Option[Seq[Node]] }/>
     assert(noAttr == attrNull)
     assert(noAttr == attrNone)
-    assert(noAttr.toString() == "<t></t>")
-    assert(attrNull.toString() == "<t></t>")
-    assert(attrNone.toString() == "<t></t>")
+    assert(noAttr == preAttrNull)
+    assert(noAttr == preAttrNone)
+
+    val noAttrStr = "<t></t>"
+    assert(noAttr.toString() == noAttrStr)
+    assert(attrNull.toString() == noAttrStr)
+    assert(attrNone.toString() == noAttrStr)
+    assert(preAttrNull.toString() == noAttrStr)
+    assert(preAttrNone.toString() == noAttrStr)
+
+    val xml1 = <t b="1" d="2"/>
+    val xml2 = <t a={ null: String } p:a={ null: String } b="1" c={ null: String } d="2"/>
+    val xml3 = <t b="1" c={ null: String } d="2" a={ null: String } p:a={ null: String }/>
+    assert(xml1 == xml2)
+    assert(xml1 == xml3)
+
+    val xml1Str = "<t d=\"2\" b=\"1\"></t>"
+    assert(xml1.toString() == xml1Str)
+    assert(xml2.toString() == xml1Str)
+    assert(xml3.toString() == xml1Str)
   }
 }