fix: title empty if AddSegment is not called

src/OrchardCore/OrchardCore.DisplayManagement/Extensions/HtmlContentExtensions.cs

@@ -0,0 +1,16 @@
+using System.IO;
+using System.Text.Encodings.Web;
+using Microsoft.AspNetCore.Html;
+
+namespace OrchardCore.DisplayManagement.Extensions;
+
+public static class HtmlContentExtensions
+{
+  public static string GetString(this IHtmlContent content)
+  {
+    using var writer = new StringWriter();
+    content.WriteTo(writer, HtmlEncoder.Default);
+
+    return writer.ToString();
+  }
+}

src/OrchardCore/OrchardCore.DisplayManagement/Title/PageTitleBuilder.cs

@@ -1,6 +1,8 @@
+using System;
 using System.Collections.Generic;
 using Microsoft.AspNetCore.Html;
 using OrchardCore.DisplayManagement.Zones;
+using OrchardCore.DisplayManagement.Extensions;
 
 namespace OrchardCore.DisplayManagement.Title
 {
@@ -48,7 +50,7 @@ public IHtmlContent GenerateTitle(IHtmlContent separator)
                 return _fixedTitle;
             }
 
-            if (_title != null)
+            if (_title != null && String.Empty != _title.GetString())
             {
                 return _title;
             }
@@ -82,6 +84,7 @@ public IHtmlContent GenerateTitle(IHtmlContent separator)
         public void Clear()
         {
             _fixedTitle = null;
+            _title = null;
             _titleParts.Clear();
         }
     }

test/OrchardCore.Tests/DisplayManagement/Title/PageTitleBuilderTests.cs

@@ -0,0 +1,128 @@
+using OrchardCore.DisplayManagement.Extensions;
+
+namespace OrchardCore.DisplayManagement.Title
+{
+    public class PageTitleBuilderTests
+    {
+        private const string SEPARATOR = " - ";
+
+        private readonly IServiceProvider _serviceProvider;
+
+        public PageTitleBuilderTests()
+        {
+            IServiceCollection serviceCollection = new ServiceCollection();
+
+            serviceCollection.AddScoped<IPageTitleBuilder, PageTitleBuilder>();
+
+            _serviceProvider = serviceCollection.BuildServiceProvider();
+        }
+
+        [Fact]
+        public void GenerateTitleEmpty()
+        {
+            var pageTitleBuilder = _serviceProvider.GetService<IPageTitleBuilder>();
+
+            Assert.Equal(String.Empty, pageTitleBuilder.GenerateTitle().GetString());
+        }
+
+        [Fact]
+        public void FixedTitleSet()
+        {
+            var pageTitleBuilder = _serviceProvider.GetService<IPageTitleBuilder>();
+            pageTitleBuilder.SetFixedTitle(new HtmlString("I'm a title"));
+
+            Assert.Equal("I'm a title", pageTitleBuilder.GenerateTitle().GetString());
+        }
+
+        [Fact]
+        public void FixedTitleClearAndCheck()
+        {
+            var pageTitleBuilder = _serviceProvider.GetService<IPageTitleBuilder>();
+            pageTitleBuilder.SetFixedTitle(new HtmlString("I'm a title"));
+            pageTitleBuilder.Clear();
+
+            Assert.Equal(String.Empty, pageTitleBuilder.GenerateTitle().GetString());
+        }
+
+        [Fact]
+        public void FixedTitleAddSegment()
+        {
+            var pageTitleBuilder = _serviceProvider.GetService<IPageTitleBuilder>();
+            pageTitleBuilder.SetFixedTitle(new HtmlString("I'm a title"));
+
+            pageTitleBuilder.AddSegment(new HtmlString("you don't see me"));
+
+            Assert.Equal("I'm a title", pageTitleBuilder.GenerateTitle().GetString());
+        }
+
+
+        [Fact]
+        public void TitleAddSegment()
+        {
+            var pageTitleBuilder = _serviceProvider.GetService<IPageTitleBuilder>();
+            pageTitleBuilder.Clear();
+
+            pageTitleBuilder.AddSegment(new HtmlString("you have to see me"), "after");
+
+            Assert.Equal("you have to see me", pageTitleBuilder.GenerateTitle().GetString());
+        }
+
+        [Fact]
+        public void TitleMultiAddSegment()
+        {
+            var pageTitleBuilder = _serviceProvider.GetService<IPageTitleBuilder>();
+            pageTitleBuilder.Clear();
+
+            pageTitleBuilder.AddSegment(new HtmlString("first part"), "after");
+
+            Assert.Equal("first part", pageTitleBuilder.GenerateTitle(new HtmlString(SEPARATOR)).GetString());
+
+            pageTitleBuilder.AddSegment(new HtmlString("second part"), "after");
+
+            Assert.Equal("first part - second part", pageTitleBuilder.GenerateTitle(new HtmlString(SEPARATOR)).GetString());
+        }
+
+        [Fact]
+        public void TitleAddAndClear()
+        {
+            var pageTitleBuilder = _serviceProvider.GetService<IPageTitleBuilder>();
+            pageTitleBuilder.Clear();
+
+            pageTitleBuilder.AddSegment(new HtmlString("first part"), "after");
+
+            Assert.Equal("first part", pageTitleBuilder.GenerateTitle(new HtmlString(SEPARATOR)).GetString());
+
+            pageTitleBuilder.Clear();
+
+            Assert.Equal(String.Empty, pageTitleBuilder.GenerateTitle(new HtmlString(SEPARATOR)).GetString());
+        }
+
+        [Fact]
+        public void TitleMultiGenerateTitle()
+        {
+            var pageTitleBuilder = _serviceProvider.GetService<IPageTitleBuilder>();
+            pageTitleBuilder.Clear();
+
+            pageTitleBuilder.AddSegment(new HtmlString("first part"), "after");
+
+            Assert.Equal("first part", pageTitleBuilder.GenerateTitle(new HtmlString(SEPARATOR)).GetString());
+            Assert.Equal("first part", pageTitleBuilder.GenerateTitle(new HtmlString(SEPARATOR)).GetString());
+        }
+
+        [Fact]
+        public void TitleAddSegments()
+        {
+            var pageTitleBuilder = (PageTitleBuilder)_serviceProvider.GetService<IPageTitleBuilder>();
+            pageTitleBuilder.Clear();
+
+            var elements = new IHtmlContent[]
+            {
+                new HtmlString("the first part"),
+                new HtmlString("the second one")
+            };
+            pageTitleBuilder.AddSegments(elements, "after");
+
+            Assert.Equal("the first part - the second one", pageTitleBuilder.GenerateTitle(new HtmlString(SEPARATOR)).GetString());
+        }
+    }
+}