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JeremyCaneyJeremyCaney
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Introduced new FindFirstParent() extension method
The new `FindFirstParent()` extension method is similar to the existing `FindFirst()` method, except it crawls the ancestors instead of the descendants. I've included a unit test for validating the functionality.
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‎OnTopic.Tests/TopicQueryingTest.cs‎

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@@ -69,6 +69,26 @@ public void FindAllByAttribute_ReturnsCorrectTopics() {
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}
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/*==========================================================================================================================
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| TEST: FIND FIRST PARENT: RETURNS CORRECT TOPIC
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\-------------------------------------------------------------------------------------------------------------------------*/
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/// <summary>
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/// Given a deeply nested <see cref="Topic"/>, returns the first parent <see cref="Topic"/> which satisfies a delegate.
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/// </summary>
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[TestMethod]
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public void FindFirstParent_ReturnsCorrectTopic() {
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var parentTopic = TopicFactory.Create("ParentTopic", "Page", 1);
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var childTopic = TopicFactory.Create("ChildTopic", "Page", 5, parentTopic);
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var grandChildTopic = TopicFactory.Create("GrandChildTopic", "Page", 20, childTopic);
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var greatGrandChildTopic = TopicFactory.Create("GreatGrandChildTopic", "Page", 7, grandChildTopic);
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var foundTopic = greatGrandChildTopic.FindFirstParent(t => t.Id.Equals(5));
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Assert.ReferenceEquals(childTopic, foundTopic);
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}
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/*==========================================================================================================================
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| TEST: GET ROOT TOPIC: RETURNS ROOT TOPIC
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\-------------------------------------------------------------------------------------------------------------------------*/

‎OnTopic/Querying/TopicExtensions.cs‎

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@@ -60,6 +60,47 @@ public static class TopicExtensions {
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}
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/*==========================================================================================================================
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| METHOD: FIND FIRST PARENT
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\-------------------------------------------------------------------------------------------------------------------------*/
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/// <summary>
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/// Finds the first instance of <see cref="Topic"/> among the parents that satisfies the delegate.
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/// </summary>
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/// <param name="topic">The instance of the <see cref="Topic"/> to operate against; populated automatically by .NET.</param>
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/// <param name="predicate">The function to validate whether a <see cref="Topic"/> should be included in the output.</param>
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/// <returns>The first instance of a parent topic to be satisfied.</returns>
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public static Topic? FindFirstParent(this Topic topic, Func<Topic, bool> predicate) {
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/*------------------------------------------------------------------------------------------------------------------------
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| Validate contracts
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\-----------------------------------------------------------------------------------------------------------------------*/
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Contract.Requires(topic, nameof(topic));
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Contract.Requires(predicate, nameof(predicate));
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/*------------------------------------------------------------------------------------------------------------------------
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| Search attributes
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\-----------------------------------------------------------------------------------------------------------------------*/
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if (predicate(topic)) {
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return topic;
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}
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/*------------------------------------------------------------------------------------------------------------------------
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| Find lowest common root
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\-----------------------------------------------------------------------------------------------------------------------*/
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while (topic.Parent != null) {
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if (predicate(topic.Parent)) {
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return topic.Parent;
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}
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topic = topic.Parent;
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}
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/*------------------------------------------------------------------------------------------------------------------------
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| Indicate no results found
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\-----------------------------------------------------------------------------------------------------------------------*/
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return null;
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}
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/*==========================================================================================================================
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| METHOD: FIND ALL
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\-------------------------------------------------------------------------------------------------------------------------*/

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