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DbContextOptionsBuilder

As explained in ASP.NET Core in Action, 3e

DbContextOptionsBuilder is an Entity Framework Core builder type for configuring the options and services used by a database context.

DbContextOptionsBuilder configures the options and services used by an EF Core DbContext. For tests, it can connect the context to a SQLite database held in memory. section 36.4

A typical SQLite in-memory test setup follows these steps:

  • Create a SqliteConnection with "DataSource=:memory:" and open it manually. section 36.4
  • Construct DbContextOptionsBuilder<AppDbContext>, call UseSqlite(connection), and retrieve the configured options through Options. section 36.4
  • Pass the options to AppDbContext, call EnsureCreated(), add test data, and use separate context instances for later queries. section 36.4

Configure a SQLite in-memory context

var connection = new SqliteConnection("DataSource=:memory:"); connection.Open(); var options = new DbContextOptionsBuilder<AppDbContext>() .UseSqlite(connection) .Options; using var context = new AppDbContext(options); context.Database.EnsureCreated(); section 36.4

Listing 36.13 Using the in-memory database provider to test an EF Core DbContext
[Fact]
public void GetRecipeDetails_CanLoadFromContext()
{
    var connection = new SqliteConnection("DataSource=:memory:");   #1
    connection.Open();                                              #2
 
    var options = new DbContextOptionsBuilder<AppDbContext>()       #3
        .UseSqlite(connection)                                      #3
        .Options;                                                   #3
 
    using (var context = new AppDbContext(options))                 #4
    {
        context.Database.EnsureCreated();                           #5
        context.Recipes.AddRange(                                   #6
            new Recipe { RecipeId = 1, Name = "Recipe1" },          #6
            new Recipe { RecipeId = 2, Name = "Recipe2" },          #6
            new Recipe { RecipeId = 3, Name = "Recipe3" });         #6
        context.SaveChanges();                                      #7
    }
    using (var context = new AppDbContext(options))                 #8
    {
        var service = new RecipeService(context);                   #9
        var recipe = service.GetRecipe (id: 2);                     #10
        Assert.NotNull(recipe);                                     #11
        Assert.Equal(2, recipe.Id);                                 #11
        Assert.Equal("Recipe2", recipe.Name);                       #11
    }
}

The complete test listing extends this setup with recipe data and assertions against the configured context. section 36.4

How ASP.NET Core in Action, 3e covers it

How deep it goes
Explains construction, connection lifetime, Options retrieval, EnsureCreated, test data, and separate DbContexts.
Examples
Uses DataSource=:memory:, an open SqliteConnection, Recipe entities, and a test method.
What it assumes
Uses EF Core DbContext and SQLite connection concepts without establishing them from zero.
What you can do after
Apply it via EF Core and SQLite to create test DbContexts backed by a shared in-memory database.
How it connects
Connects DbContextOptionsBuilder to DbContextOptions, DbContext, the SQLite provider, and EnsureCreated.
Cover of ASP.NET Core in Action, 3e
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