xmltree minor improvement (#16085)

tests/stdlib/txmltree.nim

@@ -0,0 +1,85 @@
+import xmltree
+
+
+block:
+  var
+    x: XmlNode
+
+  x = <>a(href = "http://nim-lang.org", newText("Nim rules."))
+  assert $x == """<a href="http://nim-lang.org">Nim rules.</a>"""
+
+  x = <>outer(<>inner())
+  assert $x == """<outer>
+  <inner />
+</outer>"""
+
+  x = <>outer(<>middle(<>inner1(), <>inner2(), <>inner3(), <>inner4()))
+  assert $x == """<outer>
+  <middle>
+    <inner1 />
+    <inner2 />
+    <inner3 />
+    <inner4 />
+  </middle>
+</outer>"""
+
+  x = <>l0(<>l1(<>l2(<>l3(<>l4()))))
+  assert $x == """<l0>
+  <l1>
+    <l2>
+      <l3>
+        <l4 />
+      </l3>
+    </l2>
+  </l1>
+</l0>"""
+
+  x = <>l0(<>l1p1(), <>l1p2(), <>l1p3())
+  assert $x == """<l0>
+  <l1p1 />
+  <l1p2 />
+  <l1p3 />
+</l0>"""
+
+  x = <>l0(<>l1(<>l2p1(), <>l2p2()))
+  assert $x == """<l0>
+  <l1>
+    <l2p1 />
+    <l2p2 />
+  </l1>
+</l0>"""
+
+  x = <>l0(<>l1(<>l2_1(), <>l2_2(<>l3_1(), <>l3_2(), <>l3_3(<>l4_1(), <>l4_2(), <>l4_3())), <>l2_3(), <>l2_4()))
+  assert $x == """<l0>
+  <l1>
+    <l2_1 />
+    <l2_2>
+      <l3_1 />
+      <l3_2 />
+      <l3_3>
+        <l4_1 />
+        <l4_2 />
+        <l4_3 />
+      </l3_3>
+    </l2_2>
+    <l2_3 />
+    <l2_4 />
+  </l1>
+</l0>"""
+
+  let
+    innermost = newElement("innermost")
+    middle = newXmlTree("middle", [innermost])
+  innermost.add newText("innermost text")
+  x = newXmlTree("outer", [middle])
+  assert $x == """<outer>
+  <middle>
+    <innermost>innermost text</innermost>
+  </middle>
+</outer>"""
+
+  x = newElement("myTag")
+  x.add newText("my text")
+  x.add newElement("sonTag")
+  x.add newEntity("my entity")
+  assert $x == "<myTag>my text<sonTag />&my entity;</myTag>"