Rank real fuzzy matches above near-misses [patch]

TextFilter.Test/TextFilterTests.cs

@@ -327,6 +327,25 @@
 		CollectionAssert.AreEqual(new List<string> { "hello", "hello world", "world" }, result);
 	}
 
+	[TestMethod]
+	[DataRow("hello", "hell", "say hello to everyone in the room")]
+	[DataRow("abc", "ab", "axxxxxxbxxxxxxc")]
+	[DataRow("readme", "read", "docs/ReleaseNotes/readme.md")]
+	[DataRow("config", "conf", "src/app/settings/config.json")]
+	public void RankPutsARealMatchAboveAHigherScoringNearMiss(string filter, string nearMiss, string match)
+	{
+		List<string> result = [.. TextFilter.Rank([nearMiss, match], filter)];
+		CollectionAssert.AreEqual(new List<string> { match, nearMiss }, result);
+	}
+
+	[TestMethod]
+	public void RankWithKeySelectorPutsARealMatchAboveAHigherScoringNearMiss()
+	{
+		List<(int Id, string Text)> items = [(1, "hell"), (2, "say hello to everyone in the room")];
+		List<(int Id, string Text)> result = [.. TextFilter.Rank(items, item => item.Text, "hello")];
+		CollectionAssert.AreEqual(new List<(int, string)> { (2, "say hello to everyone in the room"), (1, "hell") }, result);
+	}
+
 	[TestMethod]
 	public void RankEmptyStringsReturnsEmpty()
 	{

TextFilter/TextFilter.cs

@@ -124,7 +124,7 @@
 	private static readonly TimeSpan RegexMatchTimeout = TimeSpan.FromSeconds(1);
 
 	[System.Diagnostics.CodeAnalysis.SuppressMessage("Performance", "SYSLIB1045:Convert to 'GeneratedRegexAttribute'.", Justification = "Not available in older frameworks")]
 	private static Regex RegexMatchAnything() => new(".*", RegexOptions.Compiled);
 
 	/// <summary>
 	/// Gets a hint for the specified filter type.
@@ -201,7 +201,7 @@
 	/// <param name="keySelector">A function to extract the string key from an item.</param>
 	/// <param name="fuzzyFilter">The fuzzy filter pattern.</param>
 	/// <returns>The collection of items sorted by their match score.</returns>
-	/// <remarks>Uses fuzzy matching to rank the items by their match score.</remarks>
+	/// <remarks>Uses fuzzy matching to rank the items by their match score. Items that match the pattern always sort above items that don't, because a short near-miss can outscore a real match inside a longer string.</remarks>
 	public static IEnumerable<TItem> Rank<TItem>(IEnumerable<TItem> items, Func<TItem, string> keySelector, string fuzzyFilter)
 	{
 		Ensure.NotNull(items);
@@ -213,7 +213,8 @@
 			bool isMatch = IsMatch(keySelector(item), fuzzyFilter, out int score, TextFilterType.Fuzzy);
 			return (item, isMatch, score);
 		})
-		.OrderByDescending(t => t.score)
+		.OrderByDescending(t => t.isMatch)
+		.ThenByDescending(t => t.score)
 		.Select(t => t.item);
 	}
 
@@ -276,7 +277,7 @@
 
 			return ExcludedTokenPrefixes.Contains(prefix)
 				? TextFilterTokenType.Excluded
 				: RequiredTokenPrefixes.Contains(prefix)
 				? TextFilterTokenType.Required
 				: TextFilterTokenType.Optional;
 		})