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MockQueryable.NSubstitute 10.0.8

MockQueryable

Extensions for mocking Entity Framework Core async queries like ToListAsync, FirstOrDefaultAsync, and more using popular mocking libraries such as Moq, NSubstitute, and FakeItEasy — all without hitting the database.

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💡 Why Use MockQueryable?

Avoid hitting the real database in unit tests when querying via IQueryable:

var query = _userRepository.GetQueryable();

await query.AnyAsync(x => ...);
await query.FirstOrDefaultAsync(x => ...);
await query.ToListAsync();
// etc.

🚀 Getting Started

1. Create Test Data

var users = new List<UserEntity>
{
 new UserEntity { LastName = "Smith", DateOfBirth = new DateTime(2012, 1, 20) },
 // More test data...
};

2. Build the Mock

var mock = users.BuildMock(); // for IQueryable

3. Set Up in Your favorite Mocking Framework

Moq

_userRepository.Setup(x => x.GetQueryable()).Returns(mock);

NSubstitute

_userRepository.GetQueryable().Returns(mock);

FakeItEasy

A.CallTo(() => userRepository.GetQueryable()).Returns(mock);

🗃️ Mocking DbSet<T>

var mockDbSet = users.BuildMockDbSet();

// Moq
var repo = new TestDbSetRepository(mockDbSet.Object);

// NSubstitute / FakeItEasy
var repo = new TestDbSetRepository(mockDbSet);

🔧 Adding Custom Logic

Example: Custom FindAsync

mock.Setup(x => x.FindAsync(userId)).ReturnsAsync((object[] ids) =>
{
 var id = (Guid)ids[0];
 return users.FirstOrDefault(x => x.Id == id);
});

Example: Custom Expression Visitor

Build a mock with the custom for testing EF.Functions.Like

var mockDbSet = users.BuildMockDbSet<UserEntity, SampleLikeExpressionVisitor>();

🧩 Extend for Other Frameworks

You can even create your own extensions. Check the example here.

🔍 Sample Project

See the sample project for working examples.