Introduced unit test for mapping constructors with an AttributeDictionary

As per Feature #99, we now support mapping models that have a constructor with a single `AttributeDictionary` parameter (72ca032). In these cases, scalar properties in the `AttributeCollection` will be set via constructor, thus bypassing unnecessary calls to reflection. The new unit test confirms that this works by ensuring that such a constructor correctly sets a `Subtitle` property, without interfering with the standard handling for `Title` and `LastModified` (which are handled via compatible properties).

Author: JeremyCaney

OnTopic.Tests/TopicMappingServiceTest.cs

@@ -148,6 +148,30 @@ public async Task Map_Generic_ReturnsConvertedProperty() {
 
     }
 
+    /*==========================================================================================================================
+    | TEST: MAP: ATTRIBUTE DICTIONARY: RETURNS NEW MODEL
+    \-------------------------------------------------------------------------------------------------------------------------*/
+    /// <summary>
+    ///   Establishes a <see cref="TopicMappingService"/> and attempts to map a view model with a constructor containing a <see
+    ///   cref="AttributeDictionary"/>. Confirms that the expected model is returned.
+    /// </summary>
+    [Fact]
+    public async Task Map_AttributeDictionary_ReturnsNewModel() {
+
+      var topic                 = new Topic("Test", "Page");
+      var lastModified          = new DateTime(2021, 12, 22);
+
+      topic.Attributes.SetValue("Subtitle", "Value");
+      topic.VersionHistory.Add(lastModified);
+
+      var target                = await _mappingService.MapAsync<PageTopicViewModel>(topic).ConfigureAwait(false);
+
+      Assert.Equal("Test", target?.Title);
+      Assert.Equal("Value", target?.Subtitle);
+      Assert.Equal(lastModified, target?.LastModified);
+
+    }
+
     /*==========================================================================================================================
     | TEST: MAP: CONSTRUCTOR: RETURNS NEW MODEL
     \-------------------------------------------------------------------------------------------------------------------------*/