The `JamaClient` class is responsible for communicating between the Jama server and our application. Its responsibilities are: - Making an HTTP request to the Jama REST API. - Parsing the HTTP response. - Checking if the provided Base URL and credentials are valid. To make reports for the end user, we need to gather data about the results of specific preexisting filters. The `JamaClient` will provide the functionality to get the number of tickets that correspond to a specific filter ID. ```csharp public async Task> TryGetFilterResultCount(int filterId, IProject project) ``` As you can see, it uses an implementation of the Result pattern. This component will use external systems and therefore we need to handle errors gracefully. I will now describe all the possible scenarios of the interaction with the Jama REST API, along with the correct expected behavior and the test that will verify this. # Manual test It is nice to check if the code works when it interacts with the live Jama service, so I’ve created an `[Explicit]` test, this way it only gets triggered when started manually. You don’t want your unit tests to use external systems, because they will then test more then the code itself. ```csharp [Explicit] [Test] public async Task TryFilterResults() { // Arrange var config = new ConfigurationBuilder() .AddJsonFile(ConfigPath, true) .AddUserSecrets() .Build(); var options = config.GetSection(JamaCredentialsOptions.JamaCredentials) .Get(); Assert.That(options, Is.Not.Null, "JamaCredentials section is missing in the configuration"); var jamaOptions = Options.Create(options!); // The assert guarantees that options is not null var httpClient = new HttpClient(); var client = new JamaClient(_mockLogger.Object, httpClient, jamaOptions); // Act var result = await client.TryGetFilterResultCount(41510, _mockProject.Object); // Assert Console.WriteLine(result.Data); Assert.That(result.IsSuccess); ``` # Underlying network error When the client can’t make an HTTP request due to connectivity issues, or if the server is unable to respond. The client should return a Result instance with the error details. I wanted to implement this feature using TDD (test driven development). So, I’ve written a test beforehand and made sure it failed, before I started implementing the feature. ```csharp [Test] public async Task NetworkErrorShouldReturnResultAndNotThrow() { // Arrange var mockHttpClient = new Mock(); mockHttpClient .Protected() .Setup>( "SendAsync", ItExpr.IsAny(), ItExpr.IsAny() ) .ThrowsAsync(new HttpRequestException("Request failed")); using var httpClient = new HttpClient(mockHttpClient.Object); var client = new JamaClient(_mockLogger.Object, httpClient, _mockJamaOptions); // Act var result = await client.TryGetFilterResultCount(1, _mockProject.Object); // Assert Assert.Multiple(() => { Assert.That(result.IsSuccess, Is.False); Assert.That(result.Error, Is.InstanceOf()); }); } ``` Then in my implementation, instead of letting the Exception get thrown, I catch it and return it as member from a Result instance. ```csharp catch (HttpRequestException e) { _logger.LogError(e, "An error occurred while making a HTTP request to the Jama REST API. Details: {}", e.Message); return e; } ``` I can now run my test again and verify that my implementation passes it. # 401 | Unauthorized When the connection to the Jama REST API is successful but the server cannot validate the user, it will send a 401 response. I want to handle this error early in the app's lifecycle, ideally when the configuration values with the API credentials are loaded it. So, I wrote a separate method that will make a request, just to check the credentials. ```csharp public async Task> ValidateApiConnection() { try { var response = await _httpClient.GetAsync(""); return response.IsSuccessStatusCode ? Result.Success(true) : new HttpRequestException($"HTTP status code: " + $"{response.StatusCode}"); } catch (Exception e) { _logger.LogError(e, "An error has occured while trying to setup a connection with the Jama REST API."); return e; } } ``` When the base URL is correct, and the API credentials are valid, this method will return a `Result` with a true value. For everything else, if the base URL is not valid, the server is offline, the credentials are invalid, the Result will contain an Exception. I wrote the following test for this method: ```csharp public async Task ValidateApiConnection_ShouldReturnTrue() { // Arrange var client = new JamaClient(_mockLogger.Object, _mockHttpClient, _mockJamaOptions); // Act var result = await client.ValidateApiConnection(); // Assert Assert.That(result.IsSuccess, Is.True); } ```

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Constructing and testing the jama client

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