Should methods containing LINQ expressions be tested / mocked?

Posted by Phil.Wheeler on Stack Overflow See other posts from Stack Overflow or by Phil.Wheeler
Published on 2010-04-22T01:53:18Z Indexed on 2010/04/22 2:53 UTC
Read the original article Hit count: 370

Filed under:

unit-testing

|

linq-expressions

|

mocking

|

c#

Assuming I have a class with a method that takes a System.Linq.Expressions.Expression as a parameter, how much value is there in unit testing it?

public void IEnumerable<T> Find(Expression expression)
{
    return someCollection.Where(expression).ToList();
}

Unit testing or mocking these sorts of methods has been a mind-frying experience for me and I'm now at the point where I have to wonder whether it's all just not worth it.

How would I unit test this method using some arbitrary expression like

List<Animal> = myAnimalRepository.Find(x => x.Species == "Cat");

© Stack Overflow or respective owner

Related posts about unit-testing

Unit testing best practices for a unit testing newbie

as seen on Programmers - Search for 'Programmers'
In recent years, I have only written small components for people in larger projects or small tools. I have never written a unit test and it always seems like learning how to write them and actually making one takes a lot longer than simply firing up the program and testing for real. I am just about… >>> More
About unit testing a function in the zend framework and unit testing in general

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello people, I am diving into the world of unit testing. And i am sort of lost. I learned today that unit testing is testing if a function works. I wanted to test the following function: public function getEventById($id) { return $this->getResource('Event')->getEventById($id); } So… >>> More
Unit testing a database connection and general questions on database-dependent code and unit testing

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, If I have a method which establishes a database connection, how could this method be tested? Returning a bool in the event of a successful connection is one way, but is that the best way? From a testability method, is it best to have the connection method as one method and the method to get… >>> More
What is the objective of unit testing?

as seen on Programmers - Search for 'Programmers'
I've been working with C# for the last 2 years, and I've never done any unit testing. I just need to know what the objective of unit testing is. What kind of results do we expect from unit testing? Is code quality checked by unit testing? In my view, unit testing is the job of testers; if that is… >>> More
Unit testing newbie team needs to unit test

as seen on Programmers - Search for 'Programmers'
I'm working with a new team that has historically not done ANY unit testing. My goal is for the team to eventually employ TDD (Test Driven Development) as their natural process. But since TDD is such a radical mind shift for a non-unit testing team I thought I would just start off with writing unit… >>> More

Related posts about linq-expressions

Should methods containing LINQ expressions be tested / mocked?

as seen on Stack Overflow - Search for 'Stack Overflow'
Assuming I have a class with a method that takes a System.Linq.Expressions.Expression as a parameter, how much value is there in unit testing it? public void IEnumerable<T> Find(Expression expression) { return someCollection.Where(expression).ToList(); } Unit testing or mocking these… >>> More
Linqpad - an excellent free utility for developing and testing LINQ Expressions

as seen on Dot net Slackers - Search for 'Dot net Slackers'
Linqpad is utility for developing LINQ expressions and test them against data sources such a database or an XML file. It is available from http://www.linqpad.net/...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in… >>> More
System.Linq.Expressions.ExpressionVisitor is inaccessible due to its protection level

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm trying to follow the instructions on Creating an IQueryable LINQ Provider, but when I implement the classes which inherit from ExpressionVisitor as instructed I am told that ExpressionVisitor is inaccessible due to its protection level. Am I missing something incredibly basic? >>> More
typesafe NotifyPropertyChanged using linq expressions

as seen on Stack Overflow - Search for 'Stack Overflow'
Form Build your own MVVM I have the following code that lets us have typesafe NotifyOfPropertyChange calls: public void NotifyOfPropertyChange<TProperty>(Expression<Func<TProperty>> property) { var lambda = (LambdaExpression)property; MemberExpression memberExpression; … >>> More
Converting F# Quotations into LINQ Expressions

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I can convert a quotation of type Expr<'a -> 'b> to a Linq expression via the following snippet: /// Converts a F# Expression to a LINQ Lambda let toLambda (exp:Expr) = let linq = exp.ToLinqExpression() :?> MethodCallExpression linq.Arguments.[0] :?> LambdaExpression ///… >>> More