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How can I reset an EF7 InMemory provider between unit tests?

I am trying to use the EF7 InMemory provider for unit tests, but the persistent nature of the InMemory database between tests is causing me problems.

The following code demonstrates my issue. One test will work and the other test will always fail. Even though I set the _context to null between tests, the second test run will always have 4 records in it.

[TestClass]
public class UnitTest1
{
    private SchoolContext _context;

    [TestInitialize]
    public void Setup()
    {
        Random rng = new Random();
        
        var optionsBuilder = new DbContextOptionsBuilder<SchoolContext>();
        optionsBuilder.UseInMemoryDatabase();

        _context = new SchoolContext(optionsBuilder.Options);
        _context.Students.AddRange(
            new Student { Id = rng.Next(1,10000), Name = "Able" },
            new Student { Id = rng.Next(1,10000), Name = "Bob" }
        );
        _context.SaveChanges();
    }

    [TestCleanup]
    public void Cleanup()
    {
        _context = null;
    }

    [TestMethod]
    public void TestMethod1()
    {
        Assert.AreEqual(2, _context.Students.ToList().Count());
    }

    [TestMethod]
    public void TestMethod2()
    {
        Assert.AreEqual(2, _context.Students.ToList().Count());
    }
}

public class Student
{
    public int Id { get; set; }
    public string Name { get; set; }
}

public class SchoolContext : DbContext
{
    public SchoolContext(DbContextOptions options) : base(options) { }

    public DbSet<Student> Students { get; set; }
}
like image 945
Sailing Judo Avatar asked Nov 03 '15 03:11

Sailing Judo


5 Answers

The following call will clear the in-memory datastore.

_context.Database.EnsureDeleted();
like image 166
natemcmaster Avatar answered Oct 03 '22 19:10

natemcmaster


Bit late to the party, but i also ran into the same issue but what i ended up doing was.

Specifying a different database name for each test.

optionsBuilder.UseInMemoryDatabase(Guid.NewGuid().ToString());

That way you dont have to add

_context.Database.EnsureDeleted();

in all your tests

like image 25
R4nc1d Avatar answered Oct 03 '22 19:10

R4nc1d


Simply change your code definition of DbContextOptionsBuilder to be like following :

        var databaseName = "DatabaseNameHere";
        var dbContextOption = new DbContextOptionsBuilder<SchoolContext>()
                                    .UseInMemoryDatabase(databaseName, new InMemoryDatabaseRoot())
                                    .Options;

new InMemoryDatabaseRoot() creates a new database without the issue of Id's persisting. So you don't need now for :

       [TestCleanup]
       public void Cleanup()
       {
           _context = null;
       }
like image 33
Amin Mohamed Avatar answered Oct 03 '22 19:10

Amin Mohamed


I would go with a combination of both answers. If tests run in parallel, you could have a database being deleted while you are in the middle of running another test, so I was seeing sporadic failures when running a 30+ tests.

Give it a random db name, and ensure it gets deleted when the test is completed.

public class MyRepositoryTests : IDisposable {
  private SchoolContext _context;

  [TestInitialize]
  public void Setup() {
    var options = new DbContextOptionsBuilder<ApplicationDbContext>()
      // Generate a random db name
      .UseInMemoryDatabase(databaseName: Guid.NewGuid().ToString())
      .Options;
      _context = new ApplicationDbContext(options);
  }

  [TestCleanup]
  public void Cleanup()
    _context.Database.EnsureDeleted(); // Remove from memory
    _context.Dispose();
  }
}
like image 35
bradlis7 Avatar answered Oct 03 '22 19:10

bradlis7


I use a DbContext fixture like the following

public class DbContextFixture 
    where TDbContext : DbContext
{
    private readonly DbContextOptions _dbContextOptions = 
        new DbContextOptionsBuilder()
            .UseInMemoryDatabase("_", new InMemoryDatabaseRoot())
            .Options;

    public TDbContext CreateDbContext()
    {
        return (TDbContext)(typeof(TDbContext)
            .GetConstructor(new[] { typeof(DbContextOptions) })
            .Invoke(new[] { _dbContextOptions }));
    }
}

you can now simply do

public class MyRepositoryTests : IDisposable {
    private SchoolContext _context;
    private DbContextFixture<ApplicationDbContext> _dbContextFixture;

    [TestInitialize]
    public void Setup() {
        _dbContextFixture = new DbContextFixture<ApplicationDbContext>();
        _context = _dbContextFixture.CreateDbContext();
        _context.Students.AddRange(
            new Student { Id = rng.Next(1,10000), Name = "Able" },
            new Student { Id = rng.Next(1,10000), Name = "Bob" }
        );
        _context.SaveChanges();
    }

    [TestCleanup]
    public void Cleanup()
        _context.Dispose();
        _dbContextFixture = null;
    }

    [TestMethod]
    public void TestMethod1()
    {
        Assert.AreEqual(2, _context.Students.ToList().Count());
    }

    [TestMethod]
    public void TestMethod2()
    {
        Assert.AreEqual(2, _context.Students.ToList().Count());
    }
}

This solution is thread-safe. See my blog for details.

like image 30
Robert Jørgensgaard Engdahl Avatar answered Oct 03 '22 20:10

Robert Jørgensgaard Engdahl