Fix handling of failing entity expansion in attribute values. Add tests

that ensure entity expansion works in both expansion and non-expansion
modes by always expanding entities in attribute values.

Author: pdvrieze

core/base/src/commonMain/kotlin/nl/adaptivity/xmlutil/core/KtXmlReader.kt

@@ -921,18 +921,18 @@ public class KtXmlReader internal constructor(
      * result: if the setName parameter is set,
      * the name of the entity is stored in "name"
      */
-    private fun pushEntity() {
+    private fun pushEntity(expandEntities: Boolean = this.expandEntities) {
         readAssert('&')
         val first = peek(0)
 
         when {
             first == '#'.code -> pushCharEntity()
             first < 0 -> error(UNEXPECTED_EOF)
-            else -> pushRefEntity()
+            else -> pushRefEntity(expandEntities)
         }
     }
 
-    private fun pushRefEntity() {
+    private fun pushRefEntity(expandEntities: Boolean) {
         unresolvedEntity = false
         val first = read()
         val codeBuilder = StringBuilder(8)
@@ -1265,7 +1265,7 @@ public class KtXmlReader internal constructor(
                     '&' -> when {
                         left == curPos -> { // start with entity
                             srcBufPos = curPos
-                            pushEntity()
+                            pushEntity(expandEntities = true) // always expand attribute values
                             curPos = srcBufPos
                             left = curPos
                         }

core/base/src/commonTest/kotlin/nl/adaptivity/xmlutil/test/TestKtXmlReaderExpandEntities.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024-2025.
+ * Copyright (c) 2024-2026.
  *
  * This file is part of xmlutil.
  *
@@ -35,9 +35,18 @@ class TestKtXmlReaderExpandEntities : TestCommonReader() {
     }
 
     @Test
-    fun testReadEntityInAttribute() {
+    fun testReadEntityInAttributeExpand() {
+        testReadEntityInAttribute(true)
+    }
+
+    @Test
+    fun testReadEntityInAttributeNoExpand() {
+        testReadEntityInAttribute(false)
+    }
+
+    private fun testReadEntityInAttribute(expandEntities: Boolean) {
         val data = "<tag attr=\"&lt;xx&gt;\"/>"
-        val reader = KtXmlReader(StringReader(data))
+        val reader = KtXmlReader(StringReader(data), expandEntities)
         var e = reader.next()
         if (e == EventType.START_DOCUMENT) e = reader.next()
         assertEquals(EventType.START_ELEMENT, e)
@@ -76,6 +85,28 @@ class TestKtXmlReaderExpandEntities : TestCommonReader() {
         assertEquals( "Unknown entity \"&unknown;\" in entity expanding mode", e.message!!.substringAfter(" - "))
     }
 
+    @Test
+    fun testReadUnknownEntityInAttributeNoExpand() {
+        testReadUnknownEntityInAttribute(false)
+    }
+
+    @Test
+    fun testReadUnknownEntityInAttributeExpand() {
+        testReadUnknownEntityInAttribute(true)
+    }
+
+    private fun testReadUnknownEntityInAttribute(expandEntities: Boolean) {
+        val xml = """<tag attr="&unknown;"/>"""
+        val e = assertFailsWith<XmlException> {
+            KtXmlReader(StringReader(xml), expandEntities).use { reader ->
+                assertEquals(EventType.START_ELEMENT, reader.nextTag())
+                assertNotEquals("&unknown;", reader.getAttributeValue(0))
+                assertNotEquals("", reader.getAttributeValue(0))
+            }
+        }
+        assertEquals("Unknown entity \"&unknown;\" in entity expanding mode", e.message!!.substringAfter(" - "))
+    }
+
     @Test
     override fun testWhiteSpaceWithEntity() {
         val data = "<x>   dude &amp; &lt;dudette&gt;   </x>"