TestingCommons.RestApiClient 1.0.3

TestingCommons.RestApiClient

The RestApiClient project provides a base class for creating HTTP clients with optional Azure AD authentication. It simplifies the creation of REST API clients for testing scenarios by handling common configuration and authentication patterns.

Key Components

RestClientBase

• Abstract base class for REST API clients
• Pre-configured HttpClient with base URL
• Optional Azure AD authentication integration
• Two constructor overloads: with and without authentication

IRestClientOptions

• Interface defining configuration options for REST clients
• Contains BaseUrl property for API endpoint configuration
• Designed for dependency injection and configuration binding

Usage Examples

Basic REST Client Without Authentication

Configuration:

// appsettings.json
{
  "ApiSettings": {
    "BaseUrl": "https://api.example.com/"
  }
}

// Options class
public class ApiOptions : IRestClientOptions
{
    public string BaseUrl { get; set; }
}

// Service registration
services.Configure<ApiOptions>(configuration.GetSection("ApiSettings"));
services.AddTransient<MyApiClient>();

Client Implementation:

public class MyApiClient : RestClientBase
{
    public MyApiClient(IOptions<ApiOptions> options) : base(options)
    {
    }

    public async Task<User> GetUserAsync(int userId)
    {
        var response = await Client.GetAsync($"users/{userId}");
        response.EnsureSuccessStatusCode();
        
        var json = await response.Content.ReadAsStringAsync();
        return JsonSerializer.Deserialize<User>(json);
    }

    public async Task<User> CreateUserAsync(User user)
    {
        var json = JsonSerializer.Serialize(user);
        var content = new StringContent(json, Encoding.UTF8, "application/json");
        
        var response = await Client.PostAsync("users", content);
        response.EnsureSuccessStatusCode();
        
        var responseJson = await response.Content.ReadAsStringAsync();
        return JsonSerializer.Deserialize<User>(responseJson);
    }
}

REST Client with Azure AD Authentication

Configuration:

// appsettings.json
{
  "ApiSettings": {
    "BaseUrl": "https://secure-api.example.com/"
  },
  "AzureAd": {
    "TenantId": "your-tenant-id",
    "ClientId": "your-client-id",
    "ClientSecret": "your-client-secret",
    "Scope": ["https://secure-api.example.com/.default"]
  }
}

// Service registration
services.Configure<ApiOptions>(configuration.GetSection("ApiSettings"));
services.AddAzureAdAuthenticator(configuration);
services.AddTransient<SecureApiClient>();

Authenticated Client Implementation:

public class SecureApiClient : RestClientBase
{
    public SecureApiClient(IOptions<ApiOptions> options, AzureAdAuthenticator authenticator) 
        : base(options, authenticator)
    {
    }

    public async Task<Order> GetOrderAsync(int orderId)
    {
        // Add authentication header
        await AddAuthenticationHeaderAsync();
        
        var response = await Client.GetAsync($"orders/{orderId}");
        response.EnsureSuccessStatusCode();
        
        var json = await response.Content.ReadAsStringAsync();
        return JsonSerializer.Deserialize<Order>(json);
    }

    private async Task AddAuthenticationHeaderAsync()
    {
        if (Authenticator != null)
        {
            var token = await Authenticator.GetAccessTokenAsync();
            Client.DefaultRequestHeaders.Authorization = 
                new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", token);
        }
    }
}

Key Features

• Base URL Configuration: Automatic base URL setup for consistent API calls
• Optional Authentication: Support for Azure AD authentication when needed
• HttpClient Management: Pre-configured HttpClient with proper disposal
• Flexible Construction: Two constructor overloads for different scenarios
• Configuration-Driven: Easy setup through dependency injection
• Extensible Design: Abstract base class allows for custom implementations
• Authentication Integration: Seamless integration with Azure AD authenticator
• Testing-Friendly: Designed specifically for testing scenarios

Design Patterns

• Template Method: Base class provides structure, derived classes implement specifics
• Dependency Injection: Full support for .NET DI container
• Options Pattern: Configuration through strongly-typed options classes
• Factory Pattern: HttpClient creation and configuration handled in base class