wrap logic in try-catch and log errors (#106)

* wrap logic in try-catch and log errors

* rename and use Safely as method suffix

Author: Meir017

src/FluentAssertions.Analyzers/Utilities/FluentAssertionsAnalyzer.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
+using System.Diagnostics;
 using System.Linq;
 
 namespace FluentAssertions.Analyzers
@@ -33,7 +34,7 @@ private void AnalyzeCodeBlock(CodeBlockAnalysisContext context)
             {
                 foreach (var statement in method.Body.Statements.OfType<ExpressionStatementSyntax>())
                 {
-                    var diagnostic = AnalyzeExpression(statement.Expression, context.SemanticModel);
+                    var diagnostic = AnalyzeExpressionSafely(statement.Expression, context.SemanticModel);
                     if (diagnostic != null)
                     {
                         context.ReportDiagnostic(diagnostic);
@@ -43,7 +44,7 @@ private void AnalyzeCodeBlock(CodeBlockAnalysisContext context)
             }
             if (method.ExpressionBody != null)
             {
-                var diagnostic = AnalyzeExpression(method.ExpressionBody.Expression, context.SemanticModel);
+                var diagnostic = AnalyzeExpressionSafely(method.ExpressionBody.Expression, context.SemanticModel);
                 if (diagnostic != null)
                 {
                     context.ReportDiagnostic(diagnostic);
@@ -86,6 +87,19 @@ protected virtual Diagnostic CreateDiagnostic(TCSharpSyntaxVisitor visitor, Expr
                 location: expression.GetLocation(),
                 properties: properties);
         }
+
+        private Diagnostic AnalyzeExpressionSafely(ExpressionSyntax expression, SemanticModel semanticModel)
+        {
+            try
+            {
+                return AnalyzeExpression(expression, semanticModel);
+            }
+            catch (Exception e)
+            {
+                Console.Error.WriteLine($"Failed to analyze expression in {GetType().FullName}.\n{e}");
+                return null;
+            }
+        }
     }
 
     public abstract class FluentAssertionsAnalyzer : FluentAssertionsAnalyzer<FluentAssertionsCSharpSyntaxVisitor>

src/FluentAssertions.Analyzers/Utilities/FluentAssertionsCodeFixProvider.cs

@@ -3,6 +3,7 @@
 using Microsoft.CodeAnalysis.CodeFixes;
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
+using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Linq;
@@ -38,7 +39,7 @@ protected async Task<Document> RewriteAssertion(Document document, ExpressionSyn
         {
             var root = await document.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
 
-            var newExpression = GetNewExpression(expression, new FluentAssertionsDiagnosticProperties(properties));
+            var newExpression = GetNewExpressionSafely(expression, new FluentAssertionsDiagnosticProperties(properties));
 
             root = root.ReplaceNode(expression, newExpression);
 
@@ -89,5 +90,18 @@ protected ExpressionSyntax RenameIdentifier(ExpressionSyntax expression, string
                 .First(node => node.Identifier.Text == oldName);
             return expression.ReplaceNode(identifierNode, identifierNode.WithIdentifier(SyntaxFactory.Identifier(newName).WithTriviaFrom(identifierNode.Identifier)));
         }
+
+        private ExpressionSyntax GetNewExpressionSafely(ExpressionSyntax expression, FluentAssertionsDiagnosticProperties properties)
+        {
+            try
+            {
+                return GetNewExpression(expression, properties);
+            }
+            catch (Exception e)
+            {
+                Console.Error.WriteLine($"Failed to get new expression in {GetType().FullName}.\n{e}");
+                return expression;
+            }
+        }
     }
 }