(cake-buildGH-1537) - Refactor XmlPeek alias to use XPathNavigator to…

… handle retrieval of element values; add supporting tests

src/Cake.Common.Tests/Fixtures/XmlPeekAliasesFixture.cs

@@ -43,6 +43,11 @@ public XmlPeekAliasesFixture(bool xmlExists = true, bool xmlWithDtd = false, boo
            Context.Log.Returns(FakeLog);
        }
 
+       public void SetContent(string xml)
+       {
+           var file = ((FakeFileSystem)FileSystem).GetFile(XmlPath).SetContent(xml);
+       }
+
        public string Peek(string xpath)
        {
            return XmlPeekAliases.XmlPeek(Context, XmlPath, xpath, Settings);

src/Cake.Common.Tests/Properties/Resources.resx

@@ -1012,4 +1012,19 @@ Imports System.Runtime.CompilerServices;
 '<Assembly: AssemblyDelaySign(false)>
 '&lt;Assembly: AssemblyKeyFile("")&gt;</value>
   </data>
+  <data name="XmlPeek_Xml_With_Namespace" xml:space="preserve">
+    <value>&lt;?xml version="1.0" encoding="utf-8"?&gt;
+&lt;Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003"&gt;
+  &lt;PropertyGroup&gt;
+    &lt;WebPublishMethod&gt;FileSystem&lt;/WebPublishMethod&gt;
+    &lt;LastUsedBuildConfiguration&gt;DeploymentTemplate&lt;/LastUsedBuildConfiguration&gt;
+    &lt;LastUsedPlatform&gt;Any CPU&lt;/LastUsedPlatform&gt;
+    &lt;SiteUrlToLaunchAfterPublish /&gt;
+    &lt;LaunchSiteAfterPublish&gt;True&lt;/LaunchSiteAfterPublish&gt;
+    &lt;ExcludeApp_Data&gt;False&lt;/ExcludeApp_Data&gt;
+    &lt;publishUrl&gt;C:\Deployment\DeploymentTemplate\WebApi&lt;/publishUrl&gt;
+    &lt;DeleteExistingFiles&gt;False&lt;/DeleteExistingFiles&gt;
+  &lt;/PropertyGroup&gt;
+&lt;/Project&gt;</value>
+  </data>
 </root>

src/Cake.Common.Tests/Unit/XML/XmlPeekAliasesTests.cs

@@ -95,6 +95,34 @@ public void Should_Get_Node_Value()
                 Assert.Equal("test value", result);
             }
 
+            [Fact]
+            public void Should_Get_Element_Value()
+            {
+                // Given
+                var fixture = new XmlPeekAliasesFixture();
+
+                // When
+                var result = fixture.Peek("/configuration/test");
+
+                // Then
+                Assert.Equal("test value", result);
+            }
+
+            [Fact]
+            public void Should_Get_Element_Value_With_Namespace()
+            {
+                // Given
+                var fixture = new XmlPeekAliasesFixture();
+                fixture.SetContent(Properties.Resources.XmlPeek_Xml_With_Namespace);
+                fixture.Settings.Namespaces.Add("msbuild", "http://schemas.microsoft.com/developer/msbuild/2003");
+
+                // When
+                var result = fixture.Peek("/msbuild:Project/msbuild:PropertyGroup/msbuild:publishUrl");
+
+                // Then
+                Assert.Equal("C:\\Deployment\\DeploymentTemplate\\WebApi", result);
+            }
+
             [Fact]
             public void Should_Get_Node_Value_From_File_With_Dtd()
             {

src/Cake.Common/Xml/XmlPeekAliases.cs

@@ -132,14 +132,15 @@ private static string XmlPeek(XmlReader source, string xpath, XmlPeekSettings se
             document.PreserveWhitespace = settings.PreserveWhitespace;
             document.Load(source);
 
-            var namespaceManager = new XmlNamespaceManager(document.NameTable);
+            var navigator = document.CreateNavigator();
+            var namespaceManager = new XmlNamespaceManager(navigator.NameTable);
+
             foreach (var xmlNamespace in settings.Namespaces)
             {
                 namespaceManager.AddNamespace(xmlNamespace.Key /* Prefix */, xmlNamespace.Value /* URI */);
             }
 
-            var node = document.SelectSingleNode(xpath, namespaceManager);
-
+            var node = navigator.SelectSingleNode(xpath, namespaceManager);
             return node?.Value;
         }