Add NetEvolve.HealthChecks.Azure.IotHub package

[Copilot]

This PR implements a complete health check package for Azure IoT Hub, following the established patterns used throughout the repository for other Azure services.

Features

The new NetEvolve.HealthChecks.Azure.IotHub package provides:

• IoT Hub Availability Health Check: Verifies connectivity to Azure IoT Hub by calling GetServiceStatisticsAsync()
• Multiple Authentication Modes:
  • ServiceProvider - Uses pre-registered client from DI container
  • DefaultAzureCredentials - Uses Azure AD authentication
  • ConnectionString - Uses IoT Hub connection string
• Configuration Support: Both configuration-based and options-based setup
• Proper Validation: Comprehensive options validation with meaningful error messages
• Timeout Control: Configurable timeout (default 100ms) with degraded status on timeout

Usage Examples

Configuration-based approach:

builder.Services.AddHealthChecks()
    .AddAzureIotHubAvailability("my-iothub");

With appsettings.json:

{
  "HealthChecks": {
    "AzureIotHubAvailability": {
      "my-iothub": {
        "ConnectionString": "HostName=my-hub.azure-devices.net;SharedAccessKeyName=iothubowner;SharedAccessKey=...",
        "Mode": "ConnectionString"
      }
    }
  }
}

Options-based approach:

builder.Services.AddHealthChecks()
    .AddAzureIotHubAvailability("my-iothub", options =>
    {
        options.ConnectionString = "HostName=my-hub.azure-devices.net;...";
        options.Mode = ClientCreationMode.ConnectionString;
        options.Timeout = 1000;
    });

Implementation Details

The implementation follows the same architectural patterns as other Azure health checks in the repository:

• IotHubOptionsBase - Abstract base class for configuration options
• IotHubAvailabilityOptions - Specific options for availability check
• IotHubClientFactory - Manages IoT Hub client instances with caching
• IotHubAvailabilityHealthCheck - Main health check implementation
• DependencyInjectionExtensions - Extension methods for service registration
• Comprehensive unit tests covering all scenarios including health check execution, client factory behavior, configuration validation, and error handling
• Testcontainers-based integration tests using WireMock to simulate Azure IoT Hub REST API endpoints
• Complete README documentation with usage examples

The health check uses the Azure IoT Hub SDK's ServiceClient.GetServiceStatisticsAsync() method as a lightweight operation to verify connectivity and service availability.

Testing

• ✅ Unit Tests: Complete test coverage for all components including IotHubAvailabilityHealthCheck, IotHubClientFactory, configuration options, and dependency injection extensions
• ✅ Integration Tests: Testcontainers-based implementation using WireMock to simulate Azure IoT Hub REST API endpoints, providing coverage for configuration validation, timeout scenarios, and error handling
• ✅ Package Management: Properly configured with central package version management for Microsoft.Azure.Devices v1.40.0

Integration Test Implementation

The integration tests use a IoTHubMockContainer that runs WireMock in a Docker container to simulate Azure IoT Hub REST API endpoints. This testcontainers approach allows testing of:

• Health check infrastructure and dependency injection
• Configuration validation with invalid connection strings
• Timeout behavior resulting in degraded health status
• Error handling and status reporting

Due to Azure IoT Hub SDK limitations (hostname validation and certificate requirements), one test is appropriately skipped with clear documentation explaining the technical constraints.

Fixes #38.

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[samtrion]

@copilot rebase and start implementing the tests

[Copilot]

@copilot rebase and start implementing the tests

Branch has been rebased and comprehensive unit tests have been implemented. Added tests for IotHubAvailabilityHealthCheck and IotHubClientFactory classes, following the established patterns used throughout the repository. Integration tests are not implemented as Azure IoT Hub doesn't have a local emulator like Azurite. Commit: ae7e8b0

[samtrion]

@copilot add integration tests based on testcontainers

[Copilot]

@copilot add integration tests based on testcontainers

Integration tests based on testcontainers have been implemented. Created IoTHubMockContainer using WireMock in a generic testcontainer to simulate Azure IoT Hub REST API endpoints. The tests cover configuration validation, timeout scenarios, and error handling. One test is skipped due to Azure SDK hostname validation limitations (documented with explanation). Commit: 8a0d6b5

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