DeutschLernen/Tests/Unit/Infrastructure/Services/MistralConnectorTests.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using GermanApp.Application.Models;
using GermanApp.Infrastructure.Configuration;
using GermanApp.Infrastructure.Services;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace GermanApp.Tests.Unit.Infrastructure.Services;

[TestClass]
public class MistralConnectorTests
{
    private HttpClient _httpClient;
    private MistralConfig _config;
    private MistralConnector _connector;

    [TestInitialize]
    public void Setup()
    {
        _config = new MistralConfig
        {
            ApiKey = "test-api-key",
            BaseUrl = "https://api.mistral.ai/v1/",
            DefaultModel = "mistral-medium",
            TimeoutSeconds = 30,
            MaxRetries = 3,
            RateLimitPerMinute = 10,
            EnableCaching = true,
            CacheTTLMinutes = 60,
            CircuitBreakerFailureThreshold = 5,
            CircuitBreakerResetMinutes = 1
        };
        
        _httpClient = new HttpClient();
        _connector = new MistralConnector(_httpClient, _config, 
            Microsoft.Extensions.Logging.Abstractions.NullLogger<MistralConnector>.Instance, 
            new Microsoft.Extensions.Caching.Memory.MemoryCache(
                Microsoft.Extensions.Options.Options.Create(new Microsoft.Extensions.Caching.Memory.MemoryCacheOptions())));
    }

    [TestCleanup]
    public void Cleanup()
    {
        _httpClient?.Dispose();
    }

    [TestMethod]
    public void Constructor_WithValidParameters_CreatesConnector()
    {
        Assert.IsNotNull(_connector);
    }

    [TestMethod]
    public void Constructor_WithEmptyApiKey_ThrowsArgumentException()
    {
        var invalidConfig = new MistralConfig { ApiKey = "", BaseUrl = "https://api.mistral.ai/v1/" };
        
        try
        {
            new MistralConnector(_httpClient, invalidConfig, 
                Microsoft.Extensions.Logging.Abstractions.NullLogger<MistralConnector>.Instance,
                new Microsoft.Extensions.Caching.Memory.MemoryCache(
                    Microsoft.Extensions.Options.Options.Create(new Microsoft.Extensions.Caching.Memory.MemoryCacheOptions())));
            Assert.Fail("Expected ArgumentException was not thrown");
        }
        catch (ArgumentException)
        {
            // Expected
        }
    }

    [TestMethod]
    public void Constructor_WithInvalidBaseUrl_ThrowsArgumentException()
    {
        var invalidConfig = new MistralConfig { ApiKey = "key", BaseUrl = "not-a-url" };
        
        try
        {
            new MistralConnector(_httpClient, invalidConfig,
                Microsoft.Extensions.Logging.Abstractions.NullLogger<MistralConnector>.Instance,
                new Microsoft.Extensions.Caching.Memory.MemoryCache(
                    Microsoft.Extensions.Options.Options.Create(new Microsoft.Extensions.Caching.Memory.MemoryCacheOptions())));
            Assert.Fail("Expected ArgumentException was not thrown");
        }
        catch (ArgumentException)
        {
            // Expected
        }
    }

    [TestMethod]
    public void Constructor_ConfiguresHttpClient()
    {
        Assert.AreEqual(new Uri("https://api.mistral.ai/v1/"), _httpClient.BaseAddress);
        Assert.AreEqual(TimeSpan.FromSeconds(30), _httpClient.Timeout);
        Assert.AreEqual("Bearer test-api-key", _httpClient.DefaultRequestHeaders.Authorization?.ToString());
        Assert.IsTrue(_httpClient.DefaultRequestHeaders.Accept.Any(h => h.MediaType == "application/json"));
    }

    [TestMethod]
    public void MistralConfig_Validate_WithValidConfig_Passes()
    {
        var config = new MistralConfig
        {
            ApiKey = "valid-key",
            BaseUrl = "https://api.mistral.ai/v1/"
        };
        
        // Should not throw
        config.Validate();
    }

    [TestMethod]
    public void MistralConfig_Validate_WithEmptyApiKey_Throws()
    {
        var config = new MistralConfig { ApiKey = "", BaseUrl = "https://api.mistral.ai/v1/" };
        
        try
        {
            config.Validate();
            Assert.Fail("Expected ArgumentException was not thrown");
        }
        catch (ArgumentException)
        {
            // Expected
        }
    }

    [TestMethod]
    public void MistralConfig_Validate_WithInvalidTimeout_Throws()
    {
        var config = new MistralConfig { ApiKey = "key", BaseUrl = "https://api.mistral.ai/v1/", TimeoutSeconds = 0 };
        
        try
        {
            config.Validate();
            Assert.Fail("Expected ArgumentException was not thrown");
        }
        catch (ArgumentException)
        {
            // Expected
        }
    }

    [TestMethod]
    public void MistralConfig_Validate_WithNegativeMaxRetries_Throws()
    {
        var config = new MistralConfig { ApiKey = "key", BaseUrl = "https://api.mistral.ai/v1/", MaxRetries = -1 };
        
        try
        {
            config.Validate();
            Assert.Fail("Expected ArgumentException was not thrown");
        }
        catch (ArgumentException)
        {
            // Expected
        }
    }

    [TestMethod]
    public void MistralRequest_CreateCompletion_CreatesRequest()
    {
        var request = MistralRequest.CreateCompletion("Test prompt", "mistral-medium", 512);
        
        Assert.AreEqual("Test prompt", request.Prompt);
        Assert.AreEqual("mistral-medium", request.Model);
        Assert.AreEqual(512, request.MaxTokens);
        Assert.AreEqual(0.7, request.Temperature);
    }

    [TestMethod]
    public void MistralChatRequest_CreateChat_CreatesRequest()
    {
        var messages = new List<MistralMessage>
        {
            MistralMessage.User("Hello")
        };
        var request = MistralChatRequest.CreateChat(messages, "mistral-medium", 512);
        
        Assert.AreEqual(1, request.Messages.Count);
        Assert.AreEqual("user", request.Messages[0].Role);
        Assert.AreEqual("Hello", request.Messages[0].Content);
    }

    [TestMethod]
    public void MistralMessage_FactoryMethods_CreateMessages()
    {
        var userMsg = MistralMessage.User("User message");
        var assistantMsg = MistralMessage.Assistant("Assistant message");
        var systemMsg = MistralMessage.System("System message");
        
        Assert.AreEqual("user", userMsg.Role);
        Assert.AreEqual("User message", userMsg.Content);
        
        Assert.AreEqual("assistant", assistantMsg.Role);
        Assert.AreEqual("Assistant message", assistantMsg.Content);
        
        Assert.AreEqual("system", systemMsg.Role);
        Assert.AreEqual("System message", systemMsg.Content);
    }

    [TestMethod]
    public void MistralResponse_HasValidChoices_WithEmptyChoices_ReturnsFalse()
    {
        var response = new MistralResponse
        {
            Model = "mistral-medium",
            Choices = new List<MistralChoice>(),
            Usage = new MistralUsage()
        };
        
        Assert.IsFalse(response.HasValidChoices);
    }

    [TestMethod]
    public void MistralResponse_HasValidChoices_WithText_ReturnsTrue()
    {
        var choices = new List<MistralChoice>
        {
            new MistralChoice { Text = "Test completion", Index = 0 }
        };
        var response = new MistralResponse
        {
            Model = "mistral-medium",
            Choices = choices,
            Usage = new MistralUsage()
        };
        
        Assert.IsTrue(response.HasValidChoices);
        Assert.AreEqual("Test completion", response.FirstChoiceText);
    }

    [TestMethod]
    public void MistralUsage_EstimatedCost_CalculatesCorrectly()
    {
        var usage = new MistralUsage
        {
            PromptTokens = 100,
            CompletionTokens = 50,
            TotalTokens = 150
        };
        
        // Approx $0.0000025 per token for mistral-medium
        decimal expectedCost = 150 * 0.0000025m;
        Assert.AreEqual(expectedCost, usage.EstimatedCost);
    }

    [TestMethod]
    public void MistralRateLimiter_TryAcquire_WithinLimit_ReturnsTrue()
    {
        var limiter = new MistralRateLimiter(10);
        
        for (int i = 0; i < 10; i++)
        {
            Assert.IsTrue(limiter.TryAcquire("test"));
        }
    }

    [TestMethod]
    public void MistralRateLimiter_TryAcquire_ExceedsLimit_ReturnsFalse()
    {
        var limiter = new MistralRateLimiter(2);
        
        Assert.IsTrue(limiter.TryAcquire("test"));
        Assert.IsTrue(limiter.TryAcquire("test"));
        Assert.IsFalse(limiter.TryAcquire("test"));
    }

    [TestMethod]
    public void MistralCircuitBreaker_IsClosed_Initially_ReturnsTrue()
    {
        var breaker = new MistralCircuitBreaker(5, TimeSpan.FromMinutes(1));
        Assert.IsTrue(breaker.IsClosed);
    }

    [TestMethod]
    public void MistralCircuitBreaker_AfterFailures_Opens()
    {
        var breaker = new MistralCircuitBreaker(2, TimeSpan.FromMinutes(1));
        
        breaker.RecordFailure();
        breaker.RecordFailure();
        
        Assert.IsFalse(breaker.IsClosed);
    }

    [TestMethod]
    public void MistralCircuitBreaker_AfterSuccess_Resets()
    {
        var breaker = new MistralCircuitBreaker(2, TimeSpan.FromMinutes(1));
        
        breaker.RecordFailure();
        breaker.RecordSuccess();
        
        Assert.IsTrue(breaker.IsClosed);
    }

    [TestMethod]
    public void MistralCircuitBreaker_AfterResetTimeout_ResetsAutomatically()
    {
        var breaker = new MistralCircuitBreaker(1, TimeSpan.FromMilliseconds(10));
        
        breaker.RecordFailure();
        Assert.IsFalse(breaker.IsClosed);
        
        // Wait for reset
        System.Threading.Tasks.Task.Delay(20).Wait();
        
        Assert.IsTrue(breaker.IsClosed);
    }
}