Presentation integration tests (GraphQL)

The rule

The GraphQL layer is tested through HTTP in tests/Presentation.Tests.Integration. ApplicationErrorFilter, PageExtensions and, with authentication, AuthenticationSettings are also tested on their own in tests/Presentation.Tests.Unit (unit-tests). GraphQLApplication (a WebApplicationFactory<Program>) starts the app with the local environment, its own shared-cache in-memory SQLite database and the sample data on. Each test class creates one in a field, implements IDisposable and disposes it, so no class shares data with another.

Steps

1. Put the test in GraphQL/<Feature>/<Feature>Tests.cs with private readonly GraphQLApplication application = new(); and the Dispose pattern from the other classes.
2. Queries can go in the URL (/graphql?query={...}). Mutations and anything with variables are POSTed as { query, variables } with ToStringContent().
3. A GraphQL response is 200 OK even when it has errors. Assert the status, then errors or data.
4. For failures, assert errors[0].extensions.code (VALIDATION, NOT_FOUND) and the messages (api-conventions).
5. Find rows through the API (list, then pick one), not by hard-coded ids.
6. A schema change also updates the snapshot (schema-snapshot).
7. In a solution with authentication, its tests pass Authentication:* settings and a test signing key. See Authentication/AuthenticationTests.cs.

Example

// tests/Presentation.Tests.Integration/GraphQL/Movies/MovieTests.cs
public class MovieTests : IDisposable
{
    private readonly GraphQLApplication application = new();

    [Fact]
    public async Task Movies_ShouldReturn_MoviesList()
    {
        // Arrange
        using var client = this.application.CreateClient();

        // Act
        using var response = await client.GetAsync("/graphql?query={movies(first:50){nodes{id,title,reviewCount,averageStars,reviews{id,stars,author{id,firstName,lastName}}}}}");
        var result = (await response.Content.ReadAsStringAsync()).Deserialize<GraphData>();

        // Assert
        response.StatusCode.ShouldBe(HttpStatusCode.OK);
        result.Data.Movies.Nodes.Length.ShouldBe(50);
    }
}

Don't

• Share an application across tests with a static field or a class fixture.
• Assert only the status code. It's 200 for errors too.
• Edit appsettings files for a test. Pass settings.
• Depend on order the query doesn't promise.

Check

dotnet test tests/Presentation.Tests.Integration