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Entity Framework Core Testing Procedure

Testing is an important part of any application since it tells the developers that their application works correctly. In this tutorial we are going to learn the different techniques to employ in order to test Entity Framework Core codes. These techniques are broadly divided into testing with production database or without the production database. These are:

• Testing against the production database.
• Testing without the production database - here we use SQLite (in-memory mode) as a database fake, EF Core in-memory provider as a database fake, Mock DbSet and use repository layer to exclude EF Core entirely from testing and to fully mock the repository.

Entity Framework Core Interceptors

Entity Framework Core (EF Core) interceptors allow interception, modification and suppression of EF Core operations. Some examples include executing a command, call to SaveChanges and so on. You can download the source code from my GitHub repository.

Entity Framework Core Events and Diagnostic Listeners

Entity Framework Core Events and Diagnostic Listeners are very helpful in debugging our EF Core code. Events are called when something happens in EF Core codes. For example DbContext.SaveChangesFailed event is called when SaveChanges or SaveChangesAsync method is failed so we can use this event to find out the cause of the failure. Diagnostic listeners allow listening for any EF Core event for obtaining diagnostic information of the app. In this tutorial we are going to implement each of these 2 in our code.

Entity Framework Core Logging in details

Logging is an important aspect of any .NET app for debugging purpose. Through Logging we can generate SQL logs and Change Tracking information in Entity Framework Core. There are 2 types of logging in EF Core:

1. Simple logging
2. Microsoft.Extensions.Logging

Entity Framework Core Change Tracking

Entity Framework Core Change Tracker keeps track of all the loaded entities changes and these changes are applied to the database when SaveChanges method is called.

Entities are tracked on the following conditions :

1. Returned from a query executed on the database.
2. Attached to the DbContext by Add, Attach, Update methods.
3. A new entity connected to an existing tracked entity.

Entity Framework Core Concurrency Conflicts

Multiple users trying to update an entity data at the same time can lead to inconsistencies and data corruption. A user say Elon displays an entity data in order to update it, at this same time another user say Trump updates the same entity data before Elon saves the changes to the database. When Elon saves the data an inconsistent version is saved on the database which Elon has no knowledge. This is known as concurrency conflict.

Entity Framework Core Complex Queries

When building database driven apps we come across scenarios that require building complex queries with multiple data sources. Common examples of such cases being Joins, Group Joins and Group by, select many and so on. Here we look into such cases and understand how to build such complex queries in Entity Framework Core.

Entity Framework Core Optimization Techniques

It is necessary that we Optimize our Entity Framework Core codes so that the application remains light weight and at the same time executes faster. We can perform the optimizing techniques in EF Core by understanding which technique is best to use in a given situation. Let's discuss some of the most important ones one by one.