Unit Tests and Integration tests, are they so different?

Hi there,

in my team we have lots of service side code, which connects to other services.

of course we need to write unit tests for this code, and we need integration tests also – so we will know if it actually works with the other side.

and we use Rihno mocks to test only what we want while writing UT.

our unit tests looks something like this:

[TestMethod]
public void DoAction_SendingTrueValue_MessageReturning()
{
            ILogWriter mockLogWriter =

                      (ILogWriter)mocks.CreateMock( typeof(ILogWriter));
            mockLogWriter.LogAction("");
            LastCall.Constraints(Text.Like("MyError"));
            mocks.ReplayAll();
            MyService.LogWriter = mockLogWriter;

            string message = MyService.DoAction(true);
            Assert.AreEqual("bla", message); 
}

and on the other hand, this is our integration test:

[TestMethod]
public void DoAction_SendingTrueValue_MessageReturning()
{
            string message = MyService.DoAction(true);
            Assert.AreEqual("bla", message);

}

Of course this example is extreme but the fact is that the integration tests and the unit test very often looks almost the same, the only difference is the use of a mock.

I was thinking, how can we merge the tests and  perhaps use the same code. so I read a great idea in one of the .net blogs, we can use a simple conditional compilation symbol.

we can take the first test method, and change it a little bit:

[TestMethod]
public void DoAction_SendingTrueValue_MessageReturning()
{

            #if MOCK
            ILogWriter mockLogWriter =

                      (ILogWriter)mocks.CreateMock( typeof(ILogWriter));
            mockLogWriter.LogAction("");
            LastCall.Constraints(Text.Like("MyError"));
            mocks.ReplayAll();
            MyService.LogWriter = mockLogWriter;

           #endif

            string message = MyService.DoAction(true);
            Assert.AreEqual("bla", message); 
}

than all we need is to change one definition in the project settings and change our method to be integration test,

in the project settings you can find this:

if the “MOCK” word will be written there, the if in the test will return true, and the it will create a mock and work as a unit test. but if we remove the “MOCK” word, the if will return false, skip the creation of the mock and work as an integration test.

simple..

by the way, in case you didn’t understand, “MOCK” is only an example, you can write any word and write these #if symbols where ever you like.

Hope I helped – bye for now.

Linq – Different between "join" syntax

As I recently discovered, Linq is a very powerful query language that can help us query our objects in a very beautiful way (yes,beautiful).

Lately I had to write some join queries between lists and I found-out that linq let you do that in all kinds of ways.

So what kind of joins can we do,and what is the difference between them?

In order to explain this we need an object model,a simple one.

Lets say we are running a store. we have products and each product is created by a company.

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

   public class Product
   {
       public string Name { get; set; }
       public int CompanyId { get; set; }
   }

We will run our queries on these lists:

var companies = new List<Company>
                            {
                                new Company() {Name = "Candy's", Id = 1},
                                new Company() {Name = "Cow's",  Id = 2},
                                new Company() {Name = "Stuff",  Id = 3},
                            };

           var products = new List<Product>
                           {
                               new Product() {CompanyId = 1, Name = "Bamba"},
                               new Product() {CompanyId = 1, Name = "Bisli"},
                               new Product() {CompanyId = 2, Name = "Milk"},
                           };

Inner-join

The first join is a simple inner-join. we want to print each product from the list and it's company's name:

from product in products
join company in companies on product.CompanyId equals company.Id
select new {Product = product.Name, Company = company.Name};

If we print the result it will be:

Bamba - Candy's
Bisli - Candy's
Milk – Cow's

The query run on the products list and search the matching company.

another option to get these same result is with this "sql" syntax:

from product in products
from company in companies 
where product.CompanyId == company.Id
select new { Product = product.Name, Company = company.Name };

So what's the difference? when to use what? in a second…

Group-join

Now we would like to print a company and all of it's products.

we could use the inner-join syntax as follows:

from company in companies
join product in products on company.Id equals product.CompanyId
select new { Product = product.Name, Company = company.Name };

And get this result:

Candy's - Bamba
Candy's - Bisli
Cow's – Milk

But what if we want to print the company's name only once? or we want to keep the company's products in a list? that why we have the group join.

from company in companies
join product in products on company.Id equals product.CompanyId into companysProducts
select new { Company = company.Name,Products = companysProducts };

As you can see we added the "into" key-word and now,for each company we select it's name and a list of it's products.

The result will look like that:

Candy's
    Bamba
    Bisli
Cow's
    Milk
Stuff

Another interesting thing we can see in the query result is that the "Stuff" company appears although it has no products. that didn't happened before. this is because now we group for each company it's products. if it has no products the list will be empty. this query also called "outer-join".

Outer-join

Except for the query we saw above we have one more option to perform an outer-join. what if we wanted to print lines of type "company-product" but wanted "Stuff" (that has no products) to be in that list with empty product?

For this, we have "DefaultIfEmpty" method:

from company in companies
join product in products on company.Id equals product.CompanyId into companysProducts
from item in companysProducts.DefaultIfEmpty(new Product{Name = "No products"})
select new {Company = company.Name, Product = item.Name };

What we do is creating a "default product" that will be inserted if the companysProducts list of the current company is empty.

The result of this will be:

Candy's Bamba
Candy's Bisli
Cow's Milk
Stuff No products

Custom-join

As you noticed, all our joins so far used the "equals" comparison. but what if we want to select for each company all the products that it didn't make?? we need to use not-equal.

The "join" syntax we saw so far wont be good here. so we need to use the "from" statements to perform what we want:

from company in companies
from product in products 
where company.Id != product.CompanyId
select new { Company = company.Name,Product= product.Name };

The result will be:

Candy's Milk
Cow's Bamba
Cow's Bisli
Stuff Bamba
Stuff Bisli
Stuff Milk

(we could obviously do this with a group-join and the results would be more readable)

So now it's the time to explain "When to user what":

The "join" syntax is designed to perform equals joins in the best way,that's why when you want to use "==" operator you better use the "join" syntax – it has best performance.

When you want to use other operators than "equals" Or you want to use more than one condition (where company.id == product.CompanyId and company.state = product.state) you need to use the "from … from.. where.." syntax.

This was just the tip of the iceberg about linq queries, hope i made things a beat more understandable, and now you are able to refactor your 10 lines of "foreach" loop to one query statement(really, that what happens).

Windows live writer

A small tip to all the bloogers –

There is a very good tool the can be download from http://download.live.com/ that gives you a very powerful editor to write your blog posts.

All you have to do, is download the program and (easily) configure your blog(s) and it gives you full support in writing posts,adding pictures,videos etc…

It can even show you "quick preview" with your blog layout!

The tool also save drafts, and all you have to do is just press "Publish" and the post will be published on your blog.

It's very comfortable, especially if you have more than one blog…

highly recommended.

5 Tips on How to work in a huge team

Okay, so our company is very successful, we have lots of clients, and we have a very strict dead-line to deliver. the next thing that happened – our team grew to something like 20 programmers!! and all sitting in the same huge open space.

So there are plenty of people to write code, but there are lots of unfortunate side effects: 

• first of all – lots of stuff to do, lots of people to do it, however – things falls between the chairs, things get done twice, the code is duplicated, and so on
• there is lack of coordination between all the programmers.
• a lot of code is written and therefore – build is breaking.
• noise in the room.
• tons of questions to the experienced programmers.
• and more…

So after a lot of talks in the team we made some adjustments to our daily work so we could actually get some work done, so thanks to my team I selected 5 tips that I think will help a huge team get something done:

1. split the team – we took the team leader and added 3 more lower level managers, so each of them has 5 programmers, and each connects between the team-leader and his team. we also made sure that in each team there will be at least one experienced programmer.
2. rearrange the workspace – first of all, make sure each and every one has his privacy, it’s very important, you can do so by adding something that physically separates between the work stations. you should also arrange the workstations by the teams, so the team meeting won’t interrupt each other’s.
3. continuous integration – The best way to make sure nobody breaks the build, we use TeamCity but every other tool will do just fine.
4. Make Morning standup meetings – We use agile as our development methodology, but even if you don’t, make morning meetings – a separate meeting for each team for 10 minutes so you would understand what you accomplished yesterday and will be done today. after this we make a meeting between all the leaders and the Team leader, that is how we make sure we are coordinated.
5. Get to know all the team-mates of the team – I believe it’s very important to know all the programmers in the big team personally, so there won’t be a situation when someone don’t want to approach you because he is shy and is embarrassed to talk to you! you want people to talk to each other between the teams, that’s how things gets done best.

So that’s it, that’s what I learned by working in a huge team, I hope you could use these insights for your team.

Health!!

Expression trees

first post - yay! :)

A while ago i was debugging a method that generates a Linq query and returns IQueryable  .
I had a problem with it's results and i wanted to check-out the IQueryable object that was generated,
so I set an "Add watch" to the return value and was trying to find my generated linq. that wasn't so simple as i though.
In fact, the IQueryable dose not keeps the Linq statement as is, but saves it in an Expression object(also known as Expression tree).
You can see this in the IQueryable  interface definition:
public interface IQueryable : IEnumerable
{
   Type ElementType { get; }
   Expression Expression { get; }
   IQueryProvider Provider { get; }
}

What is an expression tree?
“Expression trees represent language-level code in the form of data”
msdn.microsoft.com
-This means that an expression tree gives us some kind of meta-data for our code.

To explain the concept of the Expression trees we need to start from the very beginning....
Lets say we have this method:
public void PrintNumbers(Func<int,bool> filter)
{
   for(int i=0;i<=10;++I)
  {
      if (filter(i))
         Console.writeline(i);
  }
}

The method takes a filter function and prints all the numbers from 1 to 10 that match the filter.

Until now we had 3 ways to do this:
1) Declare a method that match the parameter,something like this:
private bool MyFilter(int x)
{
  return (x%2) == 1;
}

And call our method like this:
PrintNumbers(MyFilter);

2) we could call it with anonymous delegates:
PrintNumbers(delegate(int x)
{
   return (x%2) == 1;
}

3) Lambdas expression:
PrintNumbers(x => (x % 2) == 1);

And Now we have a new way - Expressions:
Expression<Func<int, bool>> myExpression = x => (x % 2) == 1;

This expression is of type Func<int, bool> and assigned with lambdas expression.
when doing this assignment the expression object's properties are filled  as follows:
1)Body - the expression: (x % 2) == 1
2)Parameters - x
3)NodeType - LambdaExpression
4)Type - Func<int, bool>

Becasue expressions are nested types(that's why they are called trees) we would like to view them in a tree format.
you can download the visualizer from Visual studio 2008 sampels.

For exmple, if we run the visualizer on our current expression, we will get the following result:

Our Expression is an : ExpressionEqual which equals between (marked in pink underline) ExpressionModulo(left) and ExpressionConstant(righ).

The Expression modulo represent a modulo operation between ExpressionParamter "x" and a ConstantParameter "2' ,and the ExpressionConstant represent the const "1".

Expression trees and Linq
As I said in the begining of the post,the linq statement is saved in the Expression property of the IQueryable object. when the query is "executed" the expression is translated into sql statment.

for example, if we run the expression tree visualizer on the query:
var query = from c in db.Customers
where c.City == “London"
select new { c.City, c.CompanyName };

We will get the:

and now that we can read this, it is simpler to debug Linq queries.

There are some more usages to the Expression trees such as generating code and reflection, but thats for a diffrent post....

Barko(aka Tal)

Welcome!!

hello everybody We are Matan and Barko, and We have been .net developers for almost 5 years We both work in a big Software company in Israel. In this blog we will post some interesting stuff , mostly about .net, WCF, TFS, unit testing, ESRI technologies, Agile and more.. we hope you will enjoy what we have to say, Have fun Pair (of) Programmers