Add JUnitSerializer with bidirectional serialization and format conversion support

AGENTS.md

@@ -12,7 +12,7 @@ TestResults is a C# library for creating test result files. The library is desig
 - **Type-Safe**: Strongly-typed C# objects
 - **Cross-Platform**: Supports .NET 8, 9, and 10
 
-The library currently focuses on TRX format, with potential for additional formats in the future.
+The library supports both TRX and JUnit XML formats, with potential for additional formats in the future.
 
 ## Technologies and Dependencies
 

ARCHITECTURE.md

@@ -3,9 +3,9 @@
 ## Overview
 
 The TestResults library is a lightweight C# library designed to programmatically create test result files.
-The library currently focuses on the TRX (Test Results) format, with potential for additional formats in the future.
+The library supports both TRX (Test Results) and JUnit XML formats.
 TRX files are XML-based test result files commonly used by Visual Studio, Azure DevOps, and other Microsoft testing
-tools to store and visualize test execution results.
+tools, while JUnit XML is widely used across various CI/CD systems and testing frameworks.
 
 ## Design Philosophy
 
@@ -67,13 +67,23 @@ The `TrxSerializer` class is responsible for converting the domain model into TR
 - Produces TRX files compatible with Visual Studio and Azure DevOps
 - Handles proper formatting and schema compliance
 
+#### `JUnitSerializer`
+
+The `JUnitSerializer` class is responsible for converting between the domain model and JUnit XML format:
+
+- Uses .NET's built-in XML serialization capabilities
+- Produces JUnit XML files compatible with various CI/CD systems and testing tools
+- Can deserialize JUnit XML files back into the domain model
+- Groups test results by class name into test suites
+- Maps test outcomes to JUnit semantics (failure, error, skipped)
+
 ## Data Flow
 
 ```text
 1. User creates TestResults instance
 2. User adds TestResult objects to the Results collection
-3. User calls TrxSerializer.Serialize() to convert to TRX XML format
-4. User saves the XML string to a .trx file
+3. User calls TrxSerializer.Serialize() or JUnitSerializer.Serialize() to convert to desired format
+4. User saves the XML string to a .trx or .xml file
 ```
 
 ## Design Patterns
@@ -95,8 +105,8 @@ The library source code is organized in the `/src/DemaConsulting.TestResults/` d
 The library is designed to be extended in several ways:
 
 1. **Custom Test Outcomes**: While the standard outcomes cover most scenarios, custom outcomes could be added
-2. **Additional Metadata**: The model could be extended to support additional TRX metadata fields
-3. **Alternative Serializers**: Additional serializers could be added for other test result formats
+2. **Additional Metadata**: The model could be extended to support additional metadata fields
+3. **Alternative Serializers**: Additional serializers could be added for other test result formats (NUnit, xUnit, etc.)
 
 ## Quality Attributes
 
@@ -128,10 +138,10 @@ The library is designed to be extended in several ways:
 
 Potential enhancements that could be considered:
 
-1. **Deserialization**: Add support for reading existing TRX files back into the object model
-2. **Additional Formats**: Support for other test result formats (JUnit XML, NUnit XML, etc.)
+1. **Deserialization**: Add support for reading existing TRX and JUnit XML files back into the object model
+2. **Additional Formats**: Support for other test result formats (NUnit XML, xUnit XML, etc.)
 3. **Streaming**: Support for streaming large test result sets to avoid memory issues
-4. **Validation**: Add schema validation to ensure generated TRX files are well-formed
+4. **Validation**: Add schema validation to ensure generated files are well-formed
 
 ## Dependencies
 

README.md

@@ -8,7 +8,7 @@
 [![Quality Gate Status](https://sonarcloud.io/api/project_badges/measure?project=demaconsulting_TestResults&metric=alert_status)](https://sonarcloud.io/summary/new_code?id=demaconsulting_TestResults)
 [![Security Rating](https://sonarcloud.io/api/project_badges/measure?project=demaconsulting_TestResults&metric=security_rating)](https://sonarcloud.io/summary/new_code?id=demaconsulting_TestResults)
 
-A lightweight C# library for programmatically creating TRX (Test Results) files.
+A lightweight C# library for programmatically creating test result files in TRX and JUnit formats.
 
 ## Features
 
@@ -18,6 +18,7 @@ A lightweight C# library for programmatically creating TRX (Test Results) files.
 - 🔄 **Multi-Target** - Supports .NET 8, 9, and 10
 - 📦 **NuGet Ready** - Easy integration via NuGet package
 - ✅ **Compatible** - Generates TRX files compatible with Visual Studio, Azure DevOps, and other Microsoft testing tools
+- 📊 **Multiple Formats** - Supports both TRX and JUnit XML formats
 
 ## Installation
 
@@ -35,6 +36,8 @@ Install-Package DemaConsulting.TestResults
 
 ## Quick Start
 
+### Creating TRX Files
+
 The following code-snippet shows how to create a TRX test-results file:
 
 ```csharp
@@ -68,12 +71,71 @@ results.Results.Add(
         ErrorStackTrace = "at SomeTestClass.Test2() in Test.cs:line 15"
     });
 
-// Save the results to file
+// Save the results to TRX file
 File.WriteAllText(
     "results.trx",
     TrxSerializer.Serialize(results));
 ```
 
+### Creating JUnit XML Files
+
+The following code-snippet shows how to create a JUnit XML test-results file:
+
+```csharp
+using DemaConsulting.TestResults;
+using DemaConsulting.TestResults.IO;
+
+// Create a TestResults instance
+var results = new TestResults { Name = "SomeTests" };
+
+// Add some results
+results.Results.Add(
+    new TestResult
+    {
+        Name = "Test1",
+        ClassName = "SomeTestClass",
+        Outcome = TestOutcome.Passed,
+        Duration = TimeSpan.FromSeconds(1.5)
+    });
+
+results.Results.Add(
+    new TestResult
+    {
+        Name = "Test2",
+        ClassName = "SomeTestClass",
+        Outcome = TestOutcome.Failed,
+        ErrorMessage = "Expected value to be 42 but was 0",
+        ErrorStackTrace = "at SomeTestClass.Test2() in Test.cs:line 15"
+    });
+
+// Save the results to JUnit XML file
+File.WriteAllText(
+    "results.xml",
+    JUnitSerializer.Serialize(results));
+```
+
+### Converting Between Formats
+
+The library supports reading and converting between TRX and JUnit formats:
+
+```csharp
+using DemaConsulting.TestResults.IO;
+
+// Read JUnit XML file
+var junitXml = File.ReadAllText("junit-results.xml");
+var results = JUnitSerializer.Deserialize(junitXml);
+
+// Convert to TRX format
+var trxXml = TrxSerializer.Serialize(results);
+File.WriteAllText("converted.trx", trxXml);
+
+// Or convert TRX to JUnit
+var trxXml2 = File.ReadAllText("test-results.trx");
+var results2 = TrxSerializer.Deserialize(trxXml2);
+var junitXml2 = JUnitSerializer.Serialize(results2);
+File.WriteAllText("converted.xml", junitXml2);
+```
+
 ## Advanced Usage
 
 ### Capturing Standard Output
@@ -120,11 +182,11 @@ The library supports the following test outcomes:
 
 This library is useful when you need to:
 
-- Generate TRX files from custom test runners
-- Convert test results from other formats to TRX
+- Generate TRX or JUnit XML files from custom test runners
+- Convert test results between formats (TRX ↔ JUnit)
 - Create test reports programmatically
 - Aggregate test results from multiple sources
-- Build custom testing tools that integrate with Visual Studio or Azure DevOps
+- Build custom testing tools that integrate with Visual Studio, Azure DevOps, or CI/CD systems that consume JUnit XML
 
 ## Documentation
 

SECURITY.md

@@ -103,8 +103,8 @@ Historical security advisories can be found in the
 When using the TestResults library:
 
 1. **Keep Updated**: Always use the latest version of the library
-2. **Validate Input**: If accepting TRX file paths from users, validate and sanitize them
-3. **File Permissions**: When writing TRX files, use appropriate file permissions
+2. **Validate Input**: If accepting test result file paths from users, validate and sanitize them
+3. **File Permissions**: When writing test result files (TRX or JUnit XML), use appropriate file permissions
 4. **Error Handling**: Implement proper error handling when using the library
 5. **Code Review**: Review any code that uses this library as part of your security practices