From 86e61157981320ce3bdf3ec7cdf09aafb38a6291 Mon Sep 17 00:00:00 2001
From: Meir Blachman <meirblachman@gmail.com>
Date: Thu, 24 Oct 2024 19:48:07 +0300
Subject: [PATCH] bugfix: improve
 CollectionShouldHaveCountLessThan_CountShouldBeLessThan detection (#398)

---
 .../Tips/CollectionTests.cs                                 | 6 ++++++
 .../Tips/FluentAssertionsAnalyzer.cs                        | 2 +-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/FluentAssertions.Analyzers.Tests/Tips/CollectionTests.cs b/src/FluentAssertions.Analyzers.Tests/Tips/CollectionTests.cs
index 1c6dffd..24be0d1 100644
--- a/src/FluentAssertions.Analyzers.Tests/Tips/CollectionTests.cs
+++ b/src/FluentAssertions.Analyzers.Tests/Tips/CollectionTests.cs
@@ -516,6 +516,12 @@ public void CollectionShouldHaveCount_LengthShouldBe_TestNoAnalyzer(string asser
         [Implemented]
         public void CollectionShouldHaveCountLessThan_TestAnalyzer(string assertion) => VerifyCSharpDiagnosticCodeBlock(assertion, DiagnosticMetadata.CollectionShouldHaveCountLessThan_CountShouldBeLessThan);
 
+        [DataTestMethod]
+        [AssertionDiagnostic("(actual.Count() + 1).Should().BeLessThan(k{0});")]
+        [AssertionDiagnostic("(actual.Count() + 1).Should().BeLessThan(6{0});")]
+        [Implemented]
+        public void CollectionShouldHaveCountLessThan_TestNoAnalyzer(string assertion) => DiagnosticVerifier.VerifyCSharpDiagnosticUsingAllAnalyzers(GenerateCode.GenericIListCodeBlockAssertion(assertion));
+
         [DataTestMethod]
         [AssertionCodeFix(
             oldAssertion: "actual.Count().Should().BeLessThan(k{0});",
diff --git a/src/FluentAssertions.Analyzers/Tips/FluentAssertionsAnalyzer.cs b/src/FluentAssertions.Analyzers/Tips/FluentAssertionsAnalyzer.cs
index 41a39f8..8de4cf2 100644
--- a/src/FluentAssertions.Analyzers/Tips/FluentAssertionsAnalyzer.cs
+++ b/src/FluentAssertions.Analyzers/Tips/FluentAssertionsAnalyzer.cs
@@ -504,7 +504,7 @@ private static void AnalyzeInvocation(OperationAnalysisContext context, FluentAs
                 return;
             case "BeLessThan" when assertion.IsContainedInType(metadata.NumericAssertionsOfT2):
                 {
-                    if (invocation.TryGetFirstDescendent<IInvocationOperation>(out var invocationBeforeShould))
+                    if (invocation.TryGetSingleArgumentAs<IInvocationOperation>(out var invocationBeforeShould))
                     {
                         switch (invocationBeforeShould.TargetMethod.Name)
                         {