Test application changes to make it more accessible for plugins (third party code)

[todaysoftware]

I would like to be able to access the existing test infrastructure in Nop.Tests so we can more easily create tests for plugins.

I looked are various ways of going about it and I expect the ideal solution would be to separate out all of the test infrastructure code into its own assembly and then other test projects with actual tests (such as Nop.Test) use that.

But to minimize any impact I and looking at a different solution initially (although this could be a precursor to the more ideal solution).

Right now I am linking in the additional test code to the main Nop.Test project along with adding the plugin(s) as dependencies. But we still need some modifications to the test infrastructure to be able to do the following:

1. Apply schema migrations that the plug in requires (i.e. add necessary tables)
2. Register the additional services the plugin needs

The basic plan to solve the couple of issues above is to add some new abstract classes (and/or interfaces) and then the BaseNopTest static constructor and Init methods will need to locate these new classes to apply the changes/register services etc. This requires probably about a dozen lines of code added and won't impact the existing tests (since no concrete versions of these classes will exist).

But just looking for any feedback at this point (I could easily have missed some existing options that are there but I couldn't see anything obvious around extending the current tests to register additional services for example).

Will update this with link to the fork and additional documentation/examples etc once I have something in place (I already have a basic proof of concept working here).

[todaysoftware]

https://github.com/todaysoftware/nopCommerce/tree/issue-8197-test-application-reuse

After looking at everything decided that the split into two projects would be a better option rather than trying to link in other tests. This way a plugin can have its own isolated tests and not disturb the main test application.

Still a work in progress but initial check in adds Nop.Test.Core and Nop.Test now references that new project. All tests still passing after the change.

[todaysoftware]

Usage

1. Create a new test application which references Nop.Core.Tests and other assemblies that you want to test
2. Create a class that implements ITestNopStartup to register additional services
3. Create a class inherited from TestMigration to apply any database migrations by overriding the Up() method (if needed)
4. You can now add test classes inherited from BaseNopTest and utilising the test ServiceProvider and internal methods such as GetService etc

Note: You can use TestNopStartup<T> and TestMigration<T> as proxies to simply redirect calls to your own startup and migration code within your assemblies

Usage info copied in from pull request #8199 but may need to be updated if/when changes finalized

[Charlie-Brownie]

Aw neat!

Pulled this and works well (Haven't used the migration side yet, although it already looks a lot better than what I had done in the past). Definitely made the plugin testing way nicer!