Unit Testing Dapper with Inline Queries

Question

I know there are several question similar to mine.

• Dapper: Unit Testing SQL Queries
• Testing Dapper Queries

butI don\'t think both of above

Answer 1

Here is our approach:

1. First of all, you need to have an abstraction on top of IDbConnection to be able to mock it:

   public interface IDatabaseConnectionFactory
   {
       IDbConnection GetConnection();
   }
   

2. Your repository would get the connection from this factory and execute the Dapper query on it:

   public class ProductRepository
   {
       private readonly IDatabaseConnectionFactory connectionFactory;
   
       public ProductRepository(IDatabaseConnectionFactory connectionFactory)
       {
           this.connectionFactory = connectionFactory;
       }
   
       public Task> GetAll()
       {
           return this.connectionFactory.GetConnection().QueryAsync(
               "select * from Product");
       }
   }
   

3. Your test would create an in-memory database with some sample rows and check how the repository retrieves them:

   [Test]
   public async Task QueryTest()
   {
       // Arrange
       var products = new List
       {
           new Product { ... },
           new Product { ... }
       };
       var db = new InMemoryDatabase();
       db.Insert(products);
       connectionFactoryMock.Setup(c => c.GetConnection()).Returns(db.OpenConnection());
   
       // Act
       var result = await new ProductRepository(connectionFactoryMock.Object).GetAll();
   
       // Assert
       result.ShouldBeEquivalentTo(products);
   }
   

4. I guess there are multiple ways to implement such in-memory database; we used OrmLite on top of SQLite database:

   public class InMemoryDatabase
   {
       private readonly OrmLiteConnectionFactory dbFactory = new OrmLiteConnectionFactory(":memory:", SqliteOrmLiteDialectProvider.Instance);
   
       public IDbConnection OpenConnection() => this.dbFactory.OpenDbConnection();
   
       public void Insert(IEnumerable items)
       {
           using (var db = this.OpenConnection())
           {
               db.CreateTableIfNotExists();
               foreach (var item in items)
               {
                   db.Insert(item);
               }
           }
       }
   }