Unit testing repository using In Memory database in entity framework core
In entity framework 6 there was no built-in way of doing repository testing using an in-memory database. There were third party libraries like effort but they were also not fully compatible or keeping up with all the updated versions of entity framework .
Thankfully in entity framework core, this problem is resolved and support for the in-memory database is provided.
For using InMemory database you would need to install Microsoft.EntityFrameworkCore.InMemory nuget package and ensure that your DbContext class has a constructor which takes object of DBContextOptions
public class MyApplicationContext : DBContext
{
public MyApplicationContext()
{
}
public MyApplicationContext(DbContextOptions<MyApplicationContext> options) : base(options)
{
}
}
Below is a simple unit test using the in-memory database
public static MyApplicationContext GetTestDbContext(string dbName)
{
// Create db context options specifying in memory database
var options = new DbContextOptionsBuilder<MyApplicationContext>()
.UseInMemoryDatabase(databaseName: dbName)
.Options;
//Use this to instantiate the db context
return new MyApplicationContext(options);
}
private MyApplicationContext GetTestDatabase()
{
//Get the context
var testContext = GetTestDbContext(nameof(AddCategory_ShouldAddNewCategory_ToDatabase));
//Add some dummy categories to in memory db
var fixture = new Fixture();
var mockCategories = fixture.Create<List<Category>>();
testContext.AddRange(mockCategories);
return testContext;
}
[Fact]
public void AddCategory_ShouldAddNewCategory_ToDatabase()
{
//arrange
MyApplicationContext testContext = GetTestDatabase();
//category to be inserted
var testCategory = new Category
{
Id = 1,
Name = "Test category",
User = new MyApplicationUser
{
Id = "User_1111"
}
};
var mockLogger = new MockLogger();
//act
var repostiory = new MyApplicationRepository(testContext, mockLogger);
repostiory.AddCategory(testCategory);
//assert
testContext.Categories.ShouldContain(testCategory);
}
To know more about strategies for testing using ef core including in memory database you can refer this excellent Pluralsight course which talks about different aspects on this topic.