Ignore dictionary types from HaveElementAt (#45)

* Ignore dictionary types from HaveElementAt

* Move unit test

Author: samcragg

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

@@ -25,6 +25,14 @@ public void AssertionCallMultipleMethodWithTheSameNameAndArguments()
             DiagnosticVerifier.VerifyCSharpDiagnosticUsingAllAnalyzers(source);
         }
 
+        [TestMethod]
+        [Implemented(Reason = "https://github.com/fluentassertions/fluentassertions.analyzers/issues/44")]
+        public void CollectionShouldHaveElementAt_ShouldIgnoreDictionaryTypes()
+        {
+            string source = GenerateCode.DictionaryAssertion("actual[\"key\"].Should().Be(expectedValue);");
+            DiagnosticVerifier.VerifyCSharpDiagnostic<CollectionShouldHaveElementAtAnalyzer>(source);
+        }
+
         [TestMethod]
         [Implemented(Reason = "https://github.com/fluentassertions/fluentassertions.analyzers/issues/13")]
         public void PropertyOfIndexerShouldBe_ShouldNotThrowException()

src/FluentAssertions.Analyzers/Tips/Collections/CollectionShouldHaveElementAt.cs

@@ -5,6 +5,7 @@
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Composition;
+using System.Linq;
 
 namespace FluentAssertions.Analyzers
 {
@@ -27,6 +28,16 @@ protected override IEnumerable<FluentAssertionsCSharpSyntaxVisitor> Visitors
             }
         }
 
+        protected override bool ShouldAnalyzeVariableType(ITypeSymbol type)
+        {
+            if (type.AllInterfaces.Any(@interface => @interface.Name == "IReadOnlyDictionary" || @interface.Name == "IDictionary"))
+            {
+                return false;
+            }
+
+            return base.ShouldAnalyzeVariableType(type);
+        }
+
         public class ElementAtIndexShouldBeSyntaxVisitor : FluentAssertionsCSharpSyntaxVisitor
         {
             public ElementAtIndexShouldBeSyntaxVisitor() : base(new MemberValidator("ElementAt"), MemberValidator.Should, new MemberValidator("Be"))