Introduced test to ensure Clear(), Remove() enforce business logic

JeremyCaney · JeremyCaney · commit fa08bfb214cd · 2021-04-05T15:07:30.000-07:00
Introduced a test to ensure that calling `Clear()` enforces business logic by adding a property that will throw an exception if its set to null. This validates the behavior introduced in abfe213. And since `Clear()` now calls `Remove()`, it also effectively validates the behavior introduced in 0bccf1f. This validates the new functionality introduced as part of #79.
diff --git a/OnTopic.Tests/AttributeCollectionTest.cs b/OnTopic.Tests/AttributeCollectionTest.cs
@@ -439,6 +439,26 @@ public void SetValue_ValueChanged_IsDirty() {
 
     }
 
+    /*==========================================================================================================================
+    | TEST: CLEAR: NON-NULLABLE VALUE WITH BUSINESS LOGIC: THROWS EXCEPTION
+    \-------------------------------------------------------------------------------------------------------------------------*/
+    /// <summary>
+    ///   Sets an attribute on a topic instance with an valid value, and then attempts to clear all attributes. Ensures that the
+    ///   business logic is enforced by throwing an exception on the non-nullable property.
+    /// </summary>
+    [Fact]
+    public void Clear_NonNullableValueWithBusinessLogic_ThrowsException() {
+
+      var topic = new CustomTopic("Test", "Page");
+
+      topic.NonNullableAttribute = "Test";
+
+      Assert.Throws<ArgumentNullException>(() =>
+        topic.Attributes.Clear()
+      );
+
+    }
+
     /*==========================================================================================================================
     | TEST: CLEAR: EXISTING VALUES: IS DIRTY?
     \-------------------------------------------------------------------------------------------------------------------------*/
diff --git a/OnTopic.Tests/Entities/CustomTopic.cs b/OnTopic.Tests/Entities/CustomTopic.cs
@@ -83,6 +83,22 @@ public int NumericAttribute {
       }
     }
 
+    /*==========================================================================================================================
+    | NON-NULLABLE ATTRIBUTE
+    \-------------------------------------------------------------------------------------------------------------------------*/
+    /// <summary>
+    ///   Provides a property which does not permit null values as a means of ensuring the business logic is enforced when
+    ///   removing values.
+    /// </summary>
+    [AttributeSetter]
+    public string NonNullableAttribute {
+      get => Attributes.GetValue("NonNullableAttribute")?? "";
+      set {
+        Contract.Requires(value, nameof(value));
+        SetAttributeValue("NonNullableAttribute", value.ToString(CultureInfo.InvariantCulture));
+      }
+    }
+
     /*==========================================================================================================================
     | DATE/TIME ATTRIBUTE
     \-------------------------------------------------------------------------------------------------------------------------*/
