throwsanalyzer

ThrowsAnalyzer

Comprehensive Exception Analysis for C# with Automated Code Fixes

What is ThrowsAnalyzer?

ThrowsAnalyzer is a production-ready Roslyn analyzer that provides comprehensive exception handling analysis for C# codebases. It detects exception anti-patterns, enforces best practices, and provides automated code fixes—all integrated directly into your IDE.

Key Features

✅ 30 Diagnostic Rules covering all exception patterns ✅ 16 Automated Code Fixes for one-click issue resolution ✅ Exception Flow Analysis across method calls ✅ Async/Await Pattern Detection for safe async code ✅ Iterator Exception Analysis for yield-based methods ✅ Lambda & Event Handler exception detection ✅ Performance Analysis for exceptions in hot paths ✅ Best Practices Enforcement (naming, patterns, design)

Quick Start

Installation

dotnet add package ThrowsAnalyzer

Or via NuGet Package Manager:

Install-Package ThrowsAnalyzer

Usage

Once installed, ThrowsAnalyzer automatically analyzes your code and provides:

• Squiggly underlines for detected issues
• Light bulb suggestions for automated fixes
• Batch fixing (Fix All in Document/Project/Solution)

What It Detects

Exception Handling Issues

• ❌ Unhandled exceptions
• ❌ Missing try-catch blocks
• ❌ Empty catch blocks (exception swallowing)
• ❌ Unreachable catch clauses
• ❌ Rethrow anti-patterns (throw ex; vs throw;)

Async/Await Problems

• ❌ async void methods that throw
• ❌ Unobserved Task exceptions
• ❌ Synchronous throws in async methods

Performance Issues

• ❌ Exceptions in loops (hot path)
• ❌ Exception-based control flow

Best Practices

• ❌ Custom exceptions without "Exception" suffix
• ❌ Undocumented public API exceptions
• ❌ Methods that should use Result pattern

Example Code Fixes

Fix Rethrow Anti-Pattern

// Before
catch (Exception ex)
{
    throw ex; // ❌ Resets stack trace
}

// After (one-click fix)
catch (Exception ex)
{
    throw; // ✅ Preserves stack trace
}

Convert Async Void to Async Task

// Before
async void ProcessData() // ❌ May crash app
{
    await DoWorkAsync();
}

// After (one-click fix)
async Task ProcessData() // ✅ Exceptions can be observed
{
    await DoWorkAsync();
}

Move Exception Outside Loop

// Before
foreach (var item in items)
{
    if (item < 0)
        throw new ArgumentException(); // ❌ Performance issue
}

// After (one-click fix)
if (items.Any(i => i < 0))
    throw new ArgumentException(); // ✅ Validate before loop

foreach (var item in items)
{
    Process(item);
}

All Diagnostic Rules (THROWS001-030)

ID	Category	Description
THROWS001-003	Basic	Method throws, unhandled throws, try-catch blocks
THROWS004	Patterns	Rethrow anti-pattern detection
THROWS007-010	Catch Clauses	Ordering, empty, rethrow-only, overly broad
THROWS017-019	Flow Analysis	Unhandled calls, deep propagation, undocumented
THROWS020-022	Async	Sync throw, async void, unobserved tasks
THROWS023-024	Iterators	Deferred exceptions, try-finally timing
THROWS025-026	Lambdas	Uncaught exceptions, event handlers
THROWS027-030	Best Practices	Control flow, naming, hot path, Result

Configuration

Configure via .editorconfig:

# Set severity levels
dotnet_diagnostic.THROWS001.severity = suggestion
dotnet_diagnostic.THROWS004.severity = warning
dotnet_diagnostic.THROWS021.severity = error

# Disable specific rules
dotnet_diagnostic.THROWS030.severity = none

IDE Support

• ✅ Visual Studio 2022 (and newer)
• ✅ Visual Studio Code with C# extension
• ✅ JetBrains Rider
• ✅ Command Line via dotnet build

Why ThrowsAnalyzer?

For Teams

• Enforce consistent exception handling patterns
• Catch issues during code review automatically
• Reduce production bugs related to exceptions

For CI/CD

• Integrate into build pipelines
• Fail builds on critical exception issues
• Generate reports on exception handling quality

For Learning

• Learn exception best practices
• Understand async/await pitfalls
• See suggested improvements with explanations

Documentation

Full documentation available at:

• GitHub: https://github.com/wieslawsoltes/ThrowsAnalyzer
• Diagnostic Reference: See docs folder for detailed rule descriptions
• Examples: Sample projects demonstrating all features

Statistics

• 30 diagnostic rules
• 16 automated code fixes
• 269 unit tests (100% passing)
• 10+ supported member types (methods, properties, lambdas, etc.)

Contributing

Contributions welcome! Please see CONTRIBUTING.md for guidelines.

License

MIT License - see LICENSE file for details.

Support

• Issues: https://github.com/wieslawsoltes/ThrowsAnalyzer/issues
• Discussions: https://github.com/wieslawsoltes/ThrowsAnalyzer/discussions

ThrowsAnalyzer - Write safer C# code with comprehensive exception analysis.