Set ITopicRepository.Delete()'s isRecursive

In a previous commit, I introduced validation of `TopicRepositoryBase.Delete(…, isRecursive)`, which had not been previously validated (a0cc21c). This was a major bug in that code expected that a topic wouldn't be deleted if it had descendants would, in fact, still delete the topic and all descendants. Oops.

While this was fixed, it breaks backward compatibility since `isRecursive` was optional. As such, any code calling into `TopicRepositoryBase.Delete()` without explicitly setting `isRecursive` would not have been expecting an exception in these cases.

To "fix" this, I'm setting the `isRecursive` default to `true`. This is technically a breaking change in terms of the interface. But it avoids the bug fix from introducing a breaking change. We'll want to change this back to `false` in OnTopic 5.0.0.

Finally, to maintain forward compatibility with OnTopic 5.0.0, and for clarity, I explicitly set the `isRecursive` flag on all calls to `Delete()` from within the `OnTopic.Tests`.

As we currently maintain a good understanding of the cases where this is implemented, we have high confidence that this won't impact current implementations. Nevertheless, mea culpa!

OnTopic.Data.Caching/CachedTopicRepository.cs

@@ -148,7 +148,7 @@ public override int Save(Topic topic, bool isRecursive = false, bool isDraft = f
     | METHOD: DELETE
     \-------------------------------------------------------------------------------------------------------------------------*/
     /// <inheritdoc />
-    public override void Delete(Topic topic, bool isRecursive = false) => _dataProvider.Delete(topic, isRecursive);
+    public override void Delete(Topic topic, bool isRecursive = true) => _dataProvider.Delete(topic, isRecursive);
 
   } //Class
 } //Namespace

OnTopic.Data.Sql/SqlTopicRepository.cs

@@ -548,7 +548,7 @@ public override void Move(Topic topic, Topic target, Topic? sibling) {
     | METHOD: DELETE
     \-------------------------------------------------------------------------------------------------------------------------*/
     /// <inheritdoc />
-    public override void Delete(Topic topic, bool isRecursive = false) {
+    public override void Delete(Topic topic, bool isRecursive = true) {
 
       /*------------------------------------------------------------------------------------------------------------------------
       | Delete from memory

OnTopic.TestDoubles/DummyTopicRepository.cs

@@ -54,7 +54,7 @@ public DummyTopicRepository() : base() { }
     | METHOD: DELETE
     \-------------------------------------------------------------------------------------------------------------------------*/
     /// <inheritdoc />
-    public override void Delete(Topic topic, bool isRecursive = false) => throw new NotImplementedException();
+    public override void Delete(Topic topic, bool isRecursive = true) => throw new NotImplementedException();
 
   } //Class
 } //Namespace

OnTopic.TestDoubles/StubTopicRepository.cs

@@ -157,7 +157,7 @@ public override void Move(Topic topic, Topic target, Topic? sibling) {
     | METHOD: DELETE
     \-------------------------------------------------------------------------------------------------------------------------*/
     /// <inheritdoc />
-    public override void Delete(Topic topic, bool isRecursive = false) => base.Delete(topic, isRecursive);
+    public override void Delete(Topic topic, bool isRecursive = true) => base.Delete(topic, isRecursive);
 
     /*==========================================================================================================================
     | METHOD: GET ATTRIBUTES (PROXY)

OnTopic.Tests/ITopicRepositoryTest.cs

@@ -218,7 +218,7 @@ public void Delete_Topic_Removed() {
 
       Assert.AreEqual<int>(2, parent.Children.Count);
 
-      _topicRepository.Delete(topic);
+      _topicRepository.Delete(topic, true);
 
       Assert.AreEqual<int>(1, parent.Children.Count);
 

OnTopic.Tests/TopicRepositoryBaseTest.cs

@@ -65,7 +65,7 @@ public void Delete_DerivedTopic_ThrowsException() {
 
       derived.DerivedTopic      = child;
 
-      _topicRepository.Delete(topic);
+      _topicRepository.Delete(topic, true);
 
     }
 
@@ -85,7 +85,7 @@ public void Delete_InternallyDerivedTopic_Succeeds() {
 
       derived.DerivedTopic      = child;
 
-      _topicRepository.Delete(topic);
+      _topicRepository.Delete(topic, true);
 
       Assert.AreEqual<int>(0, root.Children.Count);
 

OnTopic/Repositories/ITopicRepository.cs

@@ -138,16 +138,23 @@ public interface ITopicRepository {
     /// <summary>
     ///   Interface method that deletes the provided topic from the tree
     /// </summary>
+    /// <remarks>
+    ///   Prior to OnTopic 4.5.0, the <paramref name="isRecursive"/> defaulted to <c>false</c>. Unfortunately, a bug in the
+    ///   implementation of <see cref="TopicRepositoryBase.Delete(Topic, Boolean)"/> resulted in this not being validated, and
+    ///   thus it operated <i>as though</i> it were <c>true</c>. This was fixed in OnTopic 4.5.0. As this bug fix potentially
+    ///   breaks prior implementations, however, the default for <paramref name="isRecursive"/> was changed to <c>true</c> in
+    ///   order to maintain backward compatibility. In OnTopic 5.0.0, this will be changed back to <c>false</c>.
+    /// </remarks>
     /// <param name="topic">The topic object to delete.</param>
     /// <param name="isRecursive">
     ///   Boolean indicator nothing whether to recurse through the topic's descendants and delete them as well. If set to false
-    ///   (the default) and the topic has children, including any nested topics, an exception will be thrown.
+    ///   and the topic has children, including any nested topics, an exception will be thrown.
     /// </param>
     /// <requires description="The topic to delete must be provided." exception="T:System.ArgumentNullException">
     ///   topic != null
     /// </requires>
     /// <exception cref="ArgumentNullException">topic</exception>
-    void Delete(Topic topic, bool isRecursive = false);
+    void Delete(Topic topic, bool isRecursive = true);
 
   } //Interface
 } //Namespace