what is a good way to get test data to a mock repo - entity-framework

Question

I have a database (SQL Server, Entity Framework) with 10-12 tables, around 5000 records. I want to code a unit test for a complex report that uses the data from those tables. What would be a good way to do that? I really do not want unit tests hitting an actual database...

Answer 1

Late to answer but its worth pointing out the NuGet package Effort allows you to fake an entire DbContext in memory from either a code-first or a database-first model.
I use it frequently & like it's ease of set up. You can use it to test issues that one could miss if trying to unit test with concrete fakes such as List<Entity>. (Issues caused by trying to load nav properties after the context is disposed for example)
A downside is that it does slow down the unit test a little1 which may be a concern for TDD or with a huge number of tests but I have always found it perfectly acceptable.
Simple use case outline for a db first set up would be as follows:
Add the nuget package for your EF version (package id: Effort.EF6 perhaps?)
Add an override to the constructor of your "MyEntities" class to enable Effort to pass in it's own connection string:
public partial class MyEntities
{
public MyEntities(DbConnection connection) : base(connection, true)
{
}
}
You can now create a 'Persistent' db store (persistent means it stays available after the context is disposed - it's not saved anywhere after the test run finishes!) with the following code:
var context = new MyEntities(Effort.EntityConnectionFactory.CreatePersistent("name=MyEntities"))
Just make sure you have the connection string to the db available in your app.config for the test project (used only to create the model)
Set up whatever mock data you need to test the context (I often have some simple data loaded using [ClassInitialize] or [TestInitialize] methods but it's easy to do whatever makes sense for your own set up):
[ClassInitialize]
public static void Initialise()
{
using (var context = new MyEntities(Effort.EntityConnectionFactory.CreatePersistent("name=MyEntities")))
{
context.Employees.Add(new Employee { Name = "John Doe", Skills = null});
context.Skills.Add(new Skill { Type = "C# Coding"});
context.SaveChanges();
}
}
Run your unit test using the in memory context:
[TestMethod]
public async Task CsSkillCanBeAssociatedWithEmployee()
{
//Arrange
using (var context = new MyEntities(Effort.EntityConnectionFactory.CreatePersistent("name=MyEntities")))
using (var sut = new SkillsMatrixService(context))
{
//Act
await sut.AddSkillToEmployeeAsync("Joe Bloggs","C# Coding");
}
//Assert
using (var context = new MyEntities(Effort.EntityConnectionFactory.CreatePersistent("name=MyEntities")))
{
var joesCSharpSkills = context
.Employees
.First(e => e.Name == "Joe Bloggs")
.Skills
.Where(s => s.Type == "C# Coding");
Assert.IsTrue(joesCSharpSkills.Any());
}
}
I'm given to understand you can load the initial set up for your db from csv config files to live in your project but I've always just set up dummy data in code as above.
1. Anecdotally, in my own (fairly limited) experience, 1 second or so is about usual to set it up and load some dummy data for a smallish model with around 20 entities and lots of nav properties - my machine isn't ultra fast. Naturally, your mileage may vary according to the complexity of your model and your hardware setup