EDennis.AspNetCore.Base 1.0.0

EDennis.AspNetCore.Base

A library with many test/sample projects, used as a basis for creating testable three-tier applications

Motivation

ASP.NET Core MVC and Entity Framework Core collectively provide a great framework for development of enterprise applications. That said, developing integration-testable three-tier applications with these technologies can be a little challenging at times. It is relatively easy to create a web application on one server that communicates with web API on another server, which in turn communicates with a database via Entity Framework; however, to set up proper, repeatable integration tests -- those that completely reset the database (whether in-memory or real) after each test -- is not straightforward, especially when dealing with three-tier solutions. Furthermore, to completely reset the database after spot testing via Swagger UI requires some extra set-up work. Collectively, these challenges motivated development of a library to facilitate testable three-tier application development.

Features

The current library has a number of features that assist with application development:

• An action filter that looks for special header values in HTTP requests in order to initialize or reset a test connection or in-memory database. Originally, this action filter fully supported both real databases and in-memory databases; however, only the in-memory databases proved to be reliable with parallel unit/integration testing. (A testing-transaction alternative to in-memory databases is still available, but it should be used only in situations where database locks are not likely -- e.g., spot testing using Swagger.)
• An ApiLauncher class that uses appsettings.json to identify, start, and stop one or more web applications. This utility class makes it easier to start and manage a set of micro-services during both automated integration testing and spot-testing (e.g., using Swagger).
• A base repository class that simplifies basic Entity Framework operations but still allows querying via Linq expressions
• A pair of design-time factory classes that allow code-first migrations without default constructors in the DbContext class. (One of these classes, in combination with the EDennis.MigrationsExtensions NuGet library, supports auto-creation of temporal tables.)
• a MaxPlusOneValueGenerator class that mostly emulates a sequence or identity during testing
• SQL scripts that identify and reset all identity values and sequences in a SQL Server database
• Extensions to IServiceCollection that use Reflection to simplify the setup of Dependency Injection for
  • Typed HttpClients
  • DbContextPools
  • Repository classes
• Extensions to HttpClient that simplify the setup of
  • Basic Http operations such as posting, putting, deleting, or getting any object of type T
  • Consecutive Http operations such as posting and then getting an object of type T -- making it easier to use HttpClient for testing.
• Two types of Controllers
  • RepoController, which is designed to work with one or more repository classes backed by Entity Framework
  • ProxyController, which is designed to work with one or more API classes backed by HttpClient instances

Constraints

• The ApiLauncher will fail if the target port for an API is unavailable.
• In order for the ApiLauncher to work appropriately with spot-testing a master Api (one that calls other APIs), the master Api must be launched using the project profile (with a port in an acceptable range), rather than using IIS Express. To reset sequences/identities at the end of a spot-testing session, be sure to suspend the application by pressing CTRL-C in the command window, rather than by closing the browser window/tab. (Upon restarting spot-testing, identities and sequences will be reset, just in case.)