How to rewrite unittest not to test actual work with database, but works only with mocks

gistfile1.cs

void Main()
{
    // add NUnit and RhinoMocks
    
    SomeRule_InsertInfo_WasInserted();
    SomeRule_GetInfo_ReciveCorrectInfo();
}

// DTO
public class Info
{
    public int Id { get; set; }
    public string Desc { get; set; }
}

// Repository incapsulates work with Database
public abstract class Repository<T>
    where T : class
{
    public abstract void Save(T entity);
    public abstract IEnumerable<T> GetAll();
}

// Class under Test
public class SomeRule
{
    private readonly Repository<Info> repository;
    
    public SomeRule(Repository<Info> repository)
    {
        this.repository = repository;
    }

    public int InsertInfoToDb(Info oInfo)
    {
        repository.Save(oInfo);
        
        return oInfo.Id;
    }
    
    public Info GetInfoFromDb(int id)
    {
        return repository.GetAll().Single(info => info.Id == id);
    }
}

// Actual unittests
[Test]
public void SomeRule_InsertInfo_WasInserted() // ex. InsertInfo
{
    // Arrange
    Info oInfo = new Info();
    oInfo.Desc = "Some Description here !!!";
    
    var repositoryMock = MockRepository.GenerateStrictMock<Repository<Info>>();
    
    repositoryMock.Expect(m => m.Save(Arg<Info>.Is.NotNull));
    
    // Act
    var savedrecordid  = new SomeRule(repositoryMock).InsertInfoToDb(oInfo);
    
    // Assert
    repositoryMock.VerifyAllExpectations();
}

[Test]
public void SomeRule_GetInfo_ReciveCorrectInfo() // ex. GetInfo
{
    // Arrange
    var expectedId = 1;
    var expectedInfo = new Info { Id = expectedId, Desc = "Something" };
    
    var repositoryMock = MockRepository.GenerateStrictMock<Repository<Info>>();
 
    repositoryMock.Expect(m => m.GetAll()).Return(new [] { expectedInfo }.AsEnumerable());
    
    // Act 
    Info receivedInfo  = new SomeRule(repositoryMock).GetInfoFromDb(expectedId);
    
    // Assert
    repositoryMock.VerifyAllExpectations();
    
    Assert.That(receivedInfo, Is.Not.Null.And.SameAs(expectedInfo));
}