bugfix: improve CollectionShouldHaveCountLessOrEqualTo_CountShouldBeLessOrEqualTo & NumericShouldBeApproximately_MathAbsShouldBeLessOrEqualTo detection (#395)

Author: Meir017

src/FluentAssertions.Analyzers.Tests/Tips/CollectionTests.cs

@@ -556,6 +556,12 @@ public void CollectionShouldHaveCount_LengthShouldBe_TestNoAnalyzer(string asser
         [Implemented]
         public void CollectionShouldHaveCountLessOrEqualTo_TestAnalyzer(string assertion) => VerifyCSharpDiagnosticCodeBlock(assertion, DiagnosticMetadata.CollectionShouldHaveCountLessOrEqualTo_CountShouldBeLessOrEqualTo);
 
+        [DataTestMethod]
+        [AssertionDiagnostic("(actual.Count() + 1).Should().BeLessOrEqualTo(k{0});")]
+        [AssertionDiagnostic("(actual.Count() + 1).Should().BeLessOrEqualTo(6{0});")]
+        [Implemented]
+        public void CollectionShouldHaveCountLessOrEqualTo_TestNoAnalyzer(string assertion) => DiagnosticVerifier.VerifyCSharpDiagnosticUsingAllAnalyzers(GenerateCode.GenericIListCodeBlockAssertion(assertion));
+
         [DataTestMethod]
         [AssertionCodeFix(
             oldAssertion: "actual.Count().Should().BeLessOrEqualTo(k{0});",

src/FluentAssertions.Analyzers.Tests/Tips/NumericTests.cs

@@ -93,6 +93,11 @@ void verifyNoDiagnostic(string type)
         [Implemented]
         public void NumericShouldBeApproximately_TestAnalyzer(string assertion) => VerifyCSharpDiagnostic(assertion, DiagnosticMetadata.NumericShouldBeApproximately_MathAbsShouldBeLessOrEqualTo);
 
+        [DataTestMethod]
+        [AssertionDiagnostic("(Math.Abs(expected - actual) + 1).Should().BeLessOrEqualTo(delta{0});")]
+        [Implemented]
+        public void NumericShouldBeApproximately_TestNoAnalyzer(string assertion) => DiagnosticVerifier.VerifyCSharpDiagnosticUsingAllAnalyzers(GenerateCode.NumericAssertion(assertion, "double"));
+
         [DataTestMethod]
         [AssertionCodeFix(
             oldAssertion: "Math.Abs(expected - actual).Should().BeLessOrEqualTo(delta{0});",

src/FluentAssertions.Analyzers/Tips/FluentAssertionsAnalyzer.cs

@@ -475,7 +475,7 @@ private static void AnalyzeInvocation(OperationAnalysisContext context, FluentAs
                 return;
             case "BeLessOrEqualTo" when assertion.IsContainedInType(metadata.NumericAssertionsOfT2):
                 {
-                    if (invocation.TryGetFirstDescendent<IInvocationOperation>(out var invocationBeforeShould))
+                    if (invocation.TryGetSingleArgumentAs<IInvocationOperation>(out var invocationBeforeShould))
                     {
                         switch (invocationBeforeShould.TargetMethod.Name)
                         {