Presentation integration tests (Web API)

The rule

tests/Presentation.Tests.Integration makes real HTTP requests to the whole application in memory. WebApiApplication (a WebApplicationFactory<Program>) starts the app with the local environment, its own shared-cache in-memory SQLite database and the sample data on, so tests never touch a file or each other.

Each test class creates one WebApiApplication in its constructor and disposes it. The constructor takes three optional arguments:

Responses are read with the Deserialize<T>() helper in Extensions/JsonSerializerExtensions.cs, which uses the API's own JSON options (json-serialization).

Steps

1. Create <Feature>EndpointTests.cs in Controllers/, IDisposable, with private readonly WebApiApplication application; created in the constructor and disposed in Dispose(bool).
2. In each test, using var client = this.application.CreateClient();, then send the request with using var response = ....
3. Assert the status code first, then the body. Read success bodies as the Application entity, failures as ProblemDetails or ValidationProblemDetails, and check Errors or Detail exactly.
4. Find the rows you need through the API (list, then pick one with the property you need), not by hard-coded ids. Sample data ids are random.
5. Write one test per documented status code of the action (test-design), plus one for a body that can't be read, such as a number sent as a string.
6. Authentication, in a solution that has it: tests that need it pass Authentication:Authority and Authentication:Audience in settings, and swap the signing key in configureServices. See Authentication/AuthenticationTests.cs.

Example

// tests/Presentation.Tests.Integration/Controllers/ReviewEndpointTests.cs
[Fact]
public async Task CreateReview_ShouldReturn_ValidationProblem()
{
    // Arrange
    using var client = this.application.CreateClient();
    var json = (new { Stars = 0, AuthorId = Guid.Empty, MovieId = Guid.Empty }).Serialize();
    using var content = new StringContent(json, Encoding.UTF8, "application/json");

    // Act
    using var response = await client.PostAsync("/api/reviews", content);
    var result = (await response.Content.ReadAsStringAsync()).Deserialize<ValidationProblemDetails>();

    // Assert
    response.StatusCode.ShouldBe(HttpStatusCode.BadRequest);
    _ = result.ShouldNotBeNull();
    result.Errors["Stars"].ShouldBe(["A star rating must be between 1 and 5."]);
}

// tests/Presentation.Tests.Integration/Authentication/AuthenticationTests.cs (only with --include-auth)
private readonly WebApiApplication application = new(
    settings: new Dictionary<string, string?>
    {
        ["Authentication:Authority"] = Authority,
        ["Authentication:Audience"] = Audience
    },
    configureServices: services => services.PostConfigure<JwtBearerOptions>(JwtBearerDefaults.AuthenticationScheme, options =>
    {
        options.Configuration = new OpenIdConnectConfiguration { Issuer = Authority };
        options.TokenValidationParameters.IssuerSigningKey = SigningKey;
        options.TokenValidationParameters.ValidIssuer = Authority;
    }));

Don't

• Share one application across test classes with IClassFixture or a static field. Each class gets its own database.
• Edit appsettings files for a test. Use settings.
• Build your own JsonSerializerOptions in a test.
• Assert only the status code when the action returns a body.
• Depend on the order rows come back in unless the action promises one.

Check

dotnet test tests/Presentation.Tests.Integration