I am new to unit testing and have read several times that we should write unit test first and then the actual code. As of now , i am writing my methods and then unit test the code.
If you write the tests first...
You tend to write the code to fit the tests. This encourages the
"simplest thing that solves the problem" type development and keeps
you focused on solving the problem not working on meta-problems.
If you write the code first...
You will be tempted to write the tests to fit the code. In effect this
is the equivalent of writing the problem to fit your answer, which is
kind of backwards and will quite often lead to tests that are of
lesser value.
Sounds good to me. However, How do i write unit tests even before having my code in place?
Am i taking the advice literally ? Does it means that i should have my POCO classes and Interfaces in place and then write unit test ?
Can anyone explain me how this is done with a simple example of say adding two numbers?
It's simple really. Red, Green, Refactor.
Red means - your code is completely broken. The syntax highlighting shows red and the test doesn't pass. Why? You haven't written any code yet.
Green means - Your application builds and the test passes. You've added the required code.
Refactor means - clean it up and make sure the test passes.
You can start by writing a test somewhat like this:
[TestMethod]
public void Can_Create_MathClass() {
var math = new MathClass();
Assert.IsNotNull(math);
}
This will fail (RED). How do you fix it? Create the class.
public class MathClass {
}
That's it. It now passes (GREEN). Next test:
[TestMethod]
public void Can_Add_Two_Numbers() {
var math = new MathClass();
var result = math.Add(1, 2);
Assert.AreEqual(3, result);
}
This also fails (RED). Create the Add method:
public class MathClass {
public int Add(int a, int b) {
return a + b;
}
}
Run the test. This will pass (GREEN).
Refactoring is a matter of cleaning up the code. It also means you can remove redundant tests. We know we have the MathClass now.. so you can completely remove the Can_Create_MathClass test. Once that is done.. you've passed REFACTOR, and can continue on.
It is important to remember that the Refactor step doesn't just mean your normal code. It also means tests. You cannot let your tests deteriorate over time. You must include them in the Refactor step.
When you create your tests first, before the code, you will find it much easier and faster to create your code. The combined time it takes to create a unit test and create some code to make it pass is about the same as just coding it up straight away. But, if you already have the unit tests you don't need to create them after the code saving you some time now and lots later.
Creating a unit test helps a developer to really consider what needs to be done. Requirements are nailed down firmly by tests. There can be no misunderstanding a specification written in the form of executable code.
The code you will create is simple and concise, implementing only the features you wanted. Other developers can see how to use this new code by browsing the tests. Input whose results are undefined will be conspicuously absent from the test suite
There is also a benefit to system design. It is often very difficult to unit test some software systems. These systems are typically built code first and testing second, often by a different team entirely. By creating tests first your design will be influenced by a desire to test everything of value to your customer. Your design will reflect this by being easier to test.
Let's take a slightly more advanced example: You want to write a method that returns the largest number from a sequence.
Firstly, write one or more units test for the method to be tested:
int[] testSeq1 = {1, 4, 8, 120, 34, 56, -1, 3, -13};
Assert.That(MaxOf(testSeq1) == 120);
And repeat for some more sequences. Also include a null parameter, a sequence with one element and an empty sequence and decide if an empty sequence or null parameter should throw an exception (and ensure that the unit test expects an exception for an empty sequence if that's the case).
It is during this process that you need to decide the name of the method and the type of its parameters.
At this point, it won't compile.
Then write a stub for the method:
public int MaxOf(IEnumerable<int> sequence)
{
return 0;
}
At this point it compiles, but the unit tests fail.
Then implement MaxOf() so that those unit tests now pass.
Doing it this way around ensures that you immediately focus on the usability of the method, since the very first thing you try to do is to use it - before even beginning to write it. You might well decide to change the method's declaration slightly at this point, based on the usage pattern.
A real world example would apply this approach to using an entire class rather than just one method. For the sake of brevity I have omitted the class from the example above.
It is possible to write the unit tests before you write any code - Visual Studio does have features to generate method stubs from the code you've written in your unit test. doing it this way around can also help understand the methods that the object will need to support - sometimes this can aid later enhancements (If you had a save to disk, that you also overload to save to Stream, this is more testable and aids spooling over the network if required later on)
I currently have the following method:
public void SetNewRandomValue() {
double newValue = numberGenerator.GenerateDouble(
genesValuesInterval.MinimumValue,
genesValuesInterval.MaximumValue
);
this.value = newValue;
}
What should be the guidelines for deciding how many tests (and which tests) to make to this method? I currently have done the following one (only after implementing the method -- that is, not test-first):
var interval = new Interval(-10, 10);
var numberGeneratorMock = new Mock<INumberGenerator>(MockBehavior.Strict);
var numberGenerator = numberGeneratorMock.Object;
double expectedValue = 5.0;
numberGeneratorMock.Setup(ng =>
ng.GenerateDouble(interval.MinimumValue, interval.MaximumValue))
.Returns(expectedValue);
var gene = new Gene(numberGenerator, 0, new Interval(-10, 10));
gene.SetNewRandomValue();
Assert.AreEqual<double>(expectedValue, gene.Value);
that basically just tests one situation. Regression-testingwise I'd say that I can't think of a way of messing up the code, turning it into mal functioning code and still have the test pass, that is, I think the method looks decently covered.
What are your opinions on this? How would you handle this little method?
Thanks
I would examine the code coverage with whatever testing tool you use, if a code coverage is available for your testing framework.
I personally like to work with either Microsoft Testing Tool or NUnit Testing Framework. I can then right-click my tests project and Test with NCover (while using NUnit), which will run the tests and tell me the percentage of code covered for each of my objects and tests.
I say that when you'll be done checking the code coverage which would result of at least a 98% code coverage, your code is likely to be well tested.
I'd recommend taking a look at Pex - it can really help generate the kind of unit tests you're looking for (i.e. figure out the different potential paths and results given a method and return value).
That test looks fine. The only thing you can actually assert about SetNewRandomValue is that the Value member is assigned afterward. You've mocked out the call to GenerateDouble and verified that Value contains the expected number, so you should be good.
You could also write a test to document (and verify) the expected behavior of Gene.SetNewRandomValue when NumberGenerator.GenerateDouble returns a value outside the specified interval.
You could definitely make a case for not unit testing this. IMHO, code inspection is a perfectly valid test methodology. You generally don't test things like property setters/getters, I think this method is simple enough to avoid unit testing for the same reason.
That said, if you really do want to test it, here's what I'd do: I'd test it with a couple values, not just once with 5. (SetNewRandomValue could be implemented as this.value = 5;, which should not pass.) I'd test it with a non-integer number, to confirm there's not a oddball cast to integer in there.
You could test that it's calling GenerateDouble with the proper parameters, though that's really testing an implementation detail. (SetNewRandomValue could be implemented as numberGenerator.GenerateDouble(0, interval.max - interval.min) + interval.min;, and that shouldn't fail the test.) You could use a real random number generator, and do SetNewRandomValue a few thousand times, and test that the values are evenly distributed in your expected range.
The method is doing three things:
Calling numberGenerator.GenerateDouble with genesValuesInterval.MinimumValue as the first parameter,
and with genesValuesInterval.MaximumValue as the second parameter,
and setting this.value to the result of that call.
Your test tests the third of these things, but not the first two. You could write two more tests that check the mock is called with the correct first and second parameters.
Edit (responding to comments below):
If the intended behaviour of this method is to set this.value to a random double within a previously specified range, then the above three tests are useful (assuming genesValuesInterval min and max are the previously specified range and that you have tests in place to assert that numberGenerator.GenerateDouble(min, max) returns a double within the specified range.
If the intended behaviour of this method is just to set this.value to a random double within (Double.MinValue, Double.MaxValue), then the first two tests are unnecessary as this is just an implementation detail.
If the inted
To answer how to test it, you should be able to describe what is the desired behavior.
Looking at your code, I assume that "Gene.SetNewRandomValue" is supposed to set self.Value to a number which falls within the Interval passed to the constructor.
I'm not super familiar with the Mock class, so I may be off base, but it appears that you are not testing that. What if your implementation had this typo?
double newValue = numberGenerator.GenerateDouble(
genesValuesInterval.MinimumValue,
genesValuesInterval.MinimumValue
);
Wouldn't your test still pass?
This question already has answers here:
How do I start unit testing?
(8 answers)
Closed 10 years ago.
So I'm starting to write a class library of useful methods I've written and picked up over the years, I'll start with two examples of code, then ask my specific questions:
I'd also like to make the argument that this is not a duplicate of some of the other, "where do I start unit testin questions."
Check network connectivity (not internet, just netwok)
public static Boolean IsNetworkConnected()
{
Boolean ret = false;
try
{
String HostName = System.Net.Dns.GetHostName();
System.Net.IPHostEntry thisHost = System.Net.Dns.GetHostEntry(HostName);
String thisIpAddr = thisHost.AddressList[0].ToString();
ret = thisIpAddr != System.Net.IPAddress.Parse("127.0.0.1").ToString();
}
catch (Exception)
{
return false;
}
return ret;
}
And my IsValiEmail method (note, I didn't write the regex)
public const String MatchEmailPattern = #"^(([\w-]+\.)+[\w-]+|([a-zA-Z]{1}|[\w-]{2,}))#"
+ #"((([0-1]?[0-9]{1,2}|25[0-5]|2[0-4][0-9])\.([0-1]?[0-9]{1,2}|25[0-5]|2[0-4][0-9])\."
+ #"([0-1]?[0-9]{1,2}|25[0-5]|2[0-4][0-9])\.([0-1]?[0-9]{1,2}|25[0-5]|2[0-4][0-9])){1}|"
+ #"([a-zA-Z]+[\w-]+\.)+[a-zA-Z]{2,4})$";
public static bool IsValidEmail(string email)
{
if (email != null && email != string.Empty)
return Regex.IsMatch(email, MatchEmailPattern);
else
return false;
}
So, my question is how do I test that these methods actually work, obviously I want to start Unit Testing more of my code which is more complex than these quick examples.
I'd like to avoid installing additional tools/frameworks if possible, but I'm open to your ideas.
update
Where should this new Unit-Test code (via the links already posted) live? In the same assembly? A seperate assembly?
Check out the book. The art of unit testing. The wiki page has a lot of great resources.
NUnit is probably the unit testing framework that best suits your need. Have a look at their quick start tutorial.
You can certainly do unit testing without a framework -- just make an app with a "test" button that runs your tests. However, I've found that it's much nicer to use an existing framework -- They're set up to allow you to easily add tests, see success/failure, and run tests automatically. Nunit is fine, or really, anything will do. MSTest is OK, if you have a version of Visual Studio that comes with it.
IsValidEmail should be easy to test: test with null, "", a valid email, and an invalid email. Then put on a black hat and try sneaking pernicious garbage in: can you make it break? But since this function only operates on its inputs, it is pretty easy to test.
IsNetworkConnected is harder to test. You call GetHostName and GetHostEntry, and you can't control what they return. This makes it hard to check all of the possible modes. Unit testing exerts strong pressure on you to separate your logic from your data retrieval. One option here would be to pass in the IPHostEntry. Of course, this would makes your exception trapping less useful, and push some of it on to the caller.
You could build a function to make the calls to GetHostName and GetHostEntry for you, then pass a delegate to the real one in your app and a fake* one in your test. At some point this strategy costs more than it delivers in value -- You'll have to make that judgment yourself, and don't waste effort on work that doesn't produce value.
*Followers of the Mock Objects technique will note that you should not mock out GetHostName and GetHostEntry, since you do not own them. If you have a mocking framework and wish to use it, feel free; Just don't mistake using their tools with following their design methods.
Testing IsNetworkConnected
Sean McMillan is right in his response that there is not much of a benefit in testing IsNetworkConnected method. It does not encapsulate much logic but only the dependencies which are not worth abstracting. However, let us pretend that it is important to unit test that method due to some reason. The following is the way in which I would go about:
public static Boolean IsNetworkConnected(IIPAddressProvider ipAddressProvider)
{
Boolean ret = false;
try
{
IPAddress thisIpAddr = ipAddressProvider.GetIPAddressOFLocalHost();
ret = thisIpAddr.ToString() != System.Net.IPAddress.Parse("127.0.0.1").ToString();
}
catch (Exception)
{
return false;
}
return ret;
}
After doing that I would write the following unit test:
Throw exception from the mock of IIPAddressProvider
Return Null IPAddress from the mock of IIPAddressProvider
Return 127.0.0.1 from the mock of IIPAddressProvider
Return different IPAddress other than 127.0.0.1 from the mock of IIPAddressProvider
Testing IsValidEmail
There is a definite value in writing unit tests for this method. You need to try postive, negative and boundary test cases. Also unit testing is form of white box testing. From your method it is clear that you need to exercise on pre-condition of the method and the regular expression while doing unit testing. The important thing here is to exercise the regular expression. There are not many code paths in the method. In my opinion you need to write the above mentioned test case scenarios. Additionally, some third party tools for doing regular expression validation should be used before you use it in your production code.
Where should the test code be located
In my opinion it should always be located in a different assembly from the production code. That is the best choice.
For the first bit of code you'll want to look into introducing Dependency Inversion so that you can mock out those dependencies and control when the method returns true and when it returns false.
For the second I'd create some NUnit tests that each pass in either valid or invalid emails and verify that the correct result is returned. You do this by either creating one test per email you're wanting to test or creating one test as a row-test (which is possible with NUnit 2.5+).
As for where the tests should live....well they can live in the same assembly or in another assembly... Best practice, at the moment, seems to be to put them in a separate assembly. If you have a project called MyProject you then create a project for your unit tests called MyProject.Tests....and as an added extra it's good to put your integration tests in another assembly called MyProject.Integration.Tests.
Some additional unit testing frameworks can be found here.
You can start with Junit, and you can use mocking framework (like mockito) to mock parts of your code that involves using Frameworks. But to use mock framework you need to isolate part of your code that uses external framework into a seperate class or interface and use mock framework to mock the external dependency.
Also in your code you are using a "==" operator for String comparision.
ret = thisIpAddr != System.Net.IPAddress.Parse("127.0.0.1").ToString();
But you should use "equals" method for String comparision .
Agreed with Asaph, NUnit is most widely used framework. That being said, if you do not want to use additional frameworks, VStudio Professional does have unit testing tools built in.
I recommend putting your tests in the same solution, in a separate project, so that you don't have to ship your tests with your assembly.
Your first case is actually not the most obvious to unit test, because your class has an external dependency which will be difficult to replicate: obviously, if the class tests that the machine is connected, the result itself will be dependent on the state of the machine. In other words, if the test fails, you don't know if it is because of your code, or because of something which is outside of the control of your code. These situations are typically approached through Mocking, but that's probably not the easiest thing to start with if you are new to unit testing!
The second case is a much better starting point; essentially you will have to create valid and invalid addresses, and pass them to your method, and check that the result is what it should be.
Closed. This question needs to be more focused. It is not currently accepting answers.
Want to improve this question? Update the question so it focuses on one problem only by editing this post.
Closed 6 years ago.
Improve this question
Using C#, I need a class called User that has a username, password, active flag, first name, last name, full name, etc.
There should be methods to authenticate and save a user. Do I just write a test for the methods? And do I even need to worry about testing the properties since they are .Net's getter and setters?
Many great responses to this are also on my question: "Beginning TDD - Challenges? Solutions? Recommendations?"
May I also recommend taking a look at my blog post (which was partly inspired by my question), I have got some good feedback on that. Namely:
I Don’t Know Where to Start?
Start afresh. Only think about writing tests when you are writing new
code. This can be re-working of old
code, or a completely new feature.
Start simple. Don’t go running off and trying to get your head round
a testing framework as well as being
TDD-esque. Debug.Assert works fine.
Use it as a starting point. It doesn’t
mess with your project or create
dependencies.
Start positive. You are trying to improve your craft, feel good about
it. I have seen plenty of developers
out there that are happy to stagnate
and not try new things to better
themselves. You are doing the right
thing, remember this and it will help
stop you from giving up.
Start ready for a challenge. It is quite hard to start getting into
testing. Expect a challenge, but
remember – challenges can be overcome.
Only Test For What You Expect
I had real problems when I first
started because I was constantly sat
there trying to figure out every
possible problem that could occur and
then trying to test for it and fix.
This is a quick way to a headache.
Testing should be a real YAGNI
process. If you know there is a
problem, then write a test for it.
Otherwise, don’t bother.
Only Test One Thing
Each test case should only ever test
one thing. If you ever find yourself
putting “and” in the test case name,
you’re doing something wrong.
I hope this means we can move on from "getters and setters" :)
Test your code, not the language.
A unit test like:
Integer i = new Integer(7);
assert (i.instanceOf(integer));
is only useful if you are writing a compiler and there is a non-zero chance that your instanceof method is not working.
Don't test stuff that you can rely on the language to enforce. In your case, I'd focus on your authenticate and save methods - and I'd write tests that made sure they could handle null values in any or all of those fields gracefully.
This got me into unit testing and it made me very happy
We just started to do unit testing.
For a long time I knew it would be good to start doing it but I had no idea how to start and more importantly what to test.
Then we had to rewrite an important piece of code in our accounting program.
This part was very complex as it involved a lot of different scenarios.
The part I'm talking about is a method to pay sales and/or purchase invoices already entered into the accounting system.
I just didn't know how to start coding it, as there were so many different payment options.
An invoice could be $100 but the customer only transferred $99.
Maybe you have sent sales invoices to a customer but you have also purchased from that customer.
So you sold him for $300 but you bought for $100. You can expect your customer to pay you $200 to settle the balance.
And what if you sold for $500 but the customer pays you only $250?
So I had a very complex problem to solve with many possibilities that one scenario would work perfectly but would be wrong on an other type of invocie/payment combination.
This is where unit testing came to the rescue.
I started to write (inside the test code) a method to create a list of invoices, both for sales and purchases.
Then I wrote a second method to create the actual payment.
Normally a user would enter that information through a user interface.
Then I created the first TestMethod, testing a very simple payment of a single invoice without any payment discounts.
All the action in the system would happen when a bankpayment would be saved to the database.
As you can see I created an invoice, created a payment (a bank transaction) and saved the transaction to disk.
In my asserts I put what should be the correct numbers ending up in the Bank transaction and in the linked Invoice.
I check for the number of payments, the payment amounts, the discount amount and the balance of the invoice after the transaction.
After the test ran I would go to the database and double check if what I expected was there.
After I wrote the test, I started coding the payment method (part of the BankHeader class).
In the coding I only bothered with code to make the first test pass. I did not yet think about the other, more complex, scenarios.
I ran the first test, fixed a small bug until my test would pass.
Then I started to write the second test, this time working with a payment discount.
After I wrote the test I modified the payment method to support discounts.
While testing for correctness with a payment discount, I also tested the simple payment.
Both tests should pass of course.
Then I worked my way down to the more complex scenarios.
1) Think of a new scenario
2) Write a test for that scenario
3) Run that single test to see if it would pass
4) If it didn't I'd debug and modify the code until it would pass.
5) While modifying code I kept on running all tests
This is how I managed to create my very complex payment method.
Without unit testing I did not know how to start coding, the problem seemed overwhelming.
With testing I could start with a simple method and extend it step by step with the assurance that the simpler scenarios would still work.
I'm sure that using unit testing saved me a few days (or weeks) of coding and is more or less guaranteeing the correctness of my method.
If I later think of a new scenario, I can just add it to the tests to see if it is working or not.
If not I can modify the code but still be sure the other scenarios are still working correctly.
This will save days and days in the maintenance and bug fixing phase.
Yes, even tested code can still have bugs if a user does things you did not think of or prevented him from doing
Below are just some of tests I created to test my payment method.
public class TestPayments
{
InvoiceDiaryHeader invoiceHeader = null;
InvoiceDiaryDetail invoiceDetail = null;
BankCashDiaryHeader bankHeader = null;
BankCashDiaryDetail bankDetail = null;
public InvoiceDiaryHeader CreateSales(string amountIncVat, bool sales, int invoiceNumber, string date)
{
......
......
}
public BankCashDiaryHeader CreateMultiplePayments(IList<InvoiceDiaryHeader> invoices, int headerNumber, decimal amount, decimal discount)
{
......
......
......
}
[TestMethod]
public void TestSingleSalesPaymentNoDiscount()
{
IList<InvoiceDiaryHeader> list = new List<InvoiceDiaryHeader>();
list.Add(CreateSales("119", true, 1, "01-09-2008"));
bankHeader = CreateMultiplePayments(list, 1, 119.00M, 0);
bankHeader.Save();
Assert.AreEqual(1, bankHeader.BankCashDetails.Count);
Assert.AreEqual(1, bankHeader.BankCashDetails[0].Payments.Count);
Assert.AreEqual(119M, bankHeader.BankCashDetails[0].Payments[0].PaymentAmount);
Assert.AreEqual(0M, bankHeader.BankCashDetails[0].Payments[0].PaymentDiscount);
Assert.AreEqual(0, bankHeader.BankCashDetails[0].Payments[0].InvoiceHeader.Balance);
}
[TestMethod]
public void TestSingleSalesPaymentDiscount()
{
IList<InvoiceDiaryHeader> list = new List<InvoiceDiaryHeader>();
list.Add(CreateSales("119", true, 2, "01-09-2008"));
bankHeader = CreateMultiplePayments(list, 2, 118.00M, 1M);
bankHeader.Save();
Assert.AreEqual(1, bankHeader.BankCashDetails.Count);
Assert.AreEqual(1, bankHeader.BankCashDetails[0].Payments.Count);
Assert.AreEqual(118M, bankHeader.BankCashDetails[0].Payments[0].PaymentAmount);
Assert.AreEqual(1M, bankHeader.BankCashDetails[0].Payments[0].PaymentDiscount);
Assert.AreEqual(0, bankHeader.BankCashDetails[0].Payments[0].InvoiceHeader.Balance);
}
[TestMethod]
[ExpectedException(typeof(ApplicationException))]
public void TestDuplicateInvoiceNumber()
{
IList<InvoiceDiaryHeader> list = new List<InvoiceDiaryHeader>();
list.Add(CreateSales("100", true, 2, "01-09-2008"));
list.Add(CreateSales("200", true, 2, "01-09-2008"));
bankHeader = CreateMultiplePayments(list, 3, 300, 0);
bankHeader.Save();
Assert.Fail("expected an ApplicationException");
}
[TestMethod]
public void TestMultipleSalesPaymentWithPaymentDiscount()
{
IList<InvoiceDiaryHeader> list = new List<InvoiceDiaryHeader>();
list.Add(CreateSales("119", true, 11, "01-09-2008"));
list.Add(CreateSales("400", true, 12, "02-09-2008"));
list.Add(CreateSales("600", true, 13, "03-09-2008"));
list.Add(CreateSales("25,40", true, 14, "04-09-2008"));
bankHeader = CreateMultiplePayments(list, 5, 1144.00M, 0.40M);
bankHeader.Save();
Assert.AreEqual(1, bankHeader.BankCashDetails.Count);
Assert.AreEqual(4, bankHeader.BankCashDetails[0].Payments.Count);
Assert.AreEqual(118.60M, bankHeader.BankCashDetails[0].Payments[0].PaymentAmount);
Assert.AreEqual(400, bankHeader.BankCashDetails[0].Payments[1].PaymentAmount);
Assert.AreEqual(600, bankHeader.BankCashDetails[0].Payments[2].PaymentAmount);
Assert.AreEqual(25.40M, bankHeader.BankCashDetails[0].Payments[3].PaymentAmount);
Assert.AreEqual(0.40M, bankHeader.BankCashDetails[0].Payments[0].PaymentDiscount);
Assert.AreEqual(0, bankHeader.BankCashDetails[0].Payments[1].PaymentDiscount);
Assert.AreEqual(0, bankHeader.BankCashDetails[0].Payments[2].PaymentDiscount);
Assert.AreEqual(0, bankHeader.BankCashDetails[0].Payments[3].PaymentDiscount);
Assert.AreEqual(0, bankHeader.BankCashDetails[0].Payments[0].InvoiceHeader.Balance);
Assert.AreEqual(0, bankHeader.BankCashDetails[0].Payments[1].InvoiceHeader.Balance);
Assert.AreEqual(0, bankHeader.BankCashDetails[0].Payments[2].InvoiceHeader.Balance);
Assert.AreEqual(0, bankHeader.BankCashDetails[0].Payments[3].InvoiceHeader.Balance);
}
[TestMethod]
public void TestSettlement()
{
IList<InvoiceDiaryHeader> list = new List<InvoiceDiaryHeader>();
list.Add(CreateSales("300", true, 43, "01-09-2008")); //Sales
list.Add(CreateSales("100", false, 6453, "02-09-2008")); //Purchase
bankHeader = CreateMultiplePayments(list, 22, 200, 0);
bankHeader.Save();
Assert.AreEqual(1, bankHeader.BankCashDetails.Count);
Assert.AreEqual(2, bankHeader.BankCashDetails[0].Payments.Count);
Assert.AreEqual(300, bankHeader.BankCashDetails[0].Payments[0].PaymentAmount);
Assert.AreEqual(-100, bankHeader.BankCashDetails[0].Payments[1].PaymentAmount);
Assert.AreEqual(0, bankHeader.BankCashDetails[0].Payments[0].InvoiceHeader.Balance);
Assert.AreEqual(0, bankHeader.BankCashDetails[0].Payments[1].InvoiceHeader.Balance);
}
If they really are trivial, then don't bother testing. Eg, if they are implemented like this;
public class User
{
public string Username { get; set; }
public string Password { get; set; }
}
If, on the other hand, you are doing something clever, (like encrypting and decrypting the password in the getter/setter) then give it a test.
The rule is that you have to test every piece of logic you write. If you implemented some specific functionality in the getters and setters I think they are worth testing. If they only assign values to some private fields, don't bother.
This question seems to be a question of where does one draw the line on what methods get tested and which don't.
The setters and getters for value assignment have been created with consistency and future growth in mind, and foreseeing that some time down the road the setter/getter may evolve into more complex operations. It would make sense to put unit tests of those methods in place, also for the sake of consistency and future growth.
Code reliability, especially while undergoing change to add additional functionality, is the primary goal. I am not aware of anyone ever getting fired for including setters/getters in the testing methodology, but I am certain there exists people who wished they had tested methods which last they were aware or can recall were simple set/get wrappers but that was no longer the case.
Maybe another member of the team expanded the set/get methods to include logic that now needs tested but didn't then create the tests. But now your code is calling these methods and you aren't aware they changed and need in-depth testing, and the testing you do in development and QA don't trigger the defect, but real business data on the first day of release does trigger it.
The two teammates will now debate over who dropped the ball and failed to put in unit tests when the set/gets morphed to include logic that can fail but isn't covered by a unit test. The teammate that originally wrote the set/gets will have an easier time coming out of this clean if the tests were implemented from day one on the simple set/gets.
My opinion is that a few minutes of "wasted" time covering ALL methods with unit tests, even trivial ones, might save days of headache down the road and loss of money/reputation of the business and loss of someone's job.
And the fact that you did wrap trivial methods with unit tests might be seen by that junior team mate when they change the trivial methods into non-trivial ones and prompt them to update the test, and now nobody is in trouble because the defect was contained from reaching production.
The way we code, and the discipline that can be seen from our code, can help others.
Another canonical answer. This, I believe, from Ron Jeffries:
Only test the code that you want to work.
Testing boilerplate code is a waste of time, but as Slavo says, if you add a side effect to your getters/setters, then you should write a test to accompany that functionality.
If you're doing test-driven development, you should write the contract (eg interface) first, then write the test(s) to exercise that interface which document the expected results/behaviour. Then write your methods themselves, without touching the code in your unit tests. Finally, grab a code coverage tool and make sure your tests exercise all the logic paths in your code.
Really trivial code like getters and setters that have no extra behaviour than setting a private field are overkill to test. In 3.0 C# even has some syntactic sugar where the compiler takes care of the private field so you don't have to program that.
I usually write lots of very simple tests verifying behaviour I expect from my classes. Even if it's simple stuff like adding two numbers. I switch a lot between writing a simple test and writing some lines of code. The reason for this is that I then can change around code without being afraid I broke things I didn't think about.
You should test everything. Right now you have getters and setters, but one day you might change them somewhat, maybe to do validation or something else. The tests you write today will be used tomorrow to make sure everything keeps on working as usual.
When you write test, you should forget considerations like "right now it's trivial". In an agile or test-driven context you should test assuming future refactoring.
Also, did you try putting in really weird values like extremely long strings, or other "bad" content? Well you should... never assume how badly your code can be abused in the future.
Generally I find that writing extensive user tests is on one side, exhausting. On the other side, though it always gives you invaluable insight on how your application should work and helps you throw away easy (and false) assumptions (like: the user name will always be less than 1000 characters in length).
For simple modules that may end up in a toolkit, or in an open source type of project, you should test as much as possible including the trivial getters and setters. The thing you want to keep in mind is that generating a unit test as you write a particular module is fairly simple and straight forward. Adding getters and setters is minimal code and can be handled without much thought. However, once your code is placed in a larger system, this extra effort can protect you against changes in the underlying system, such as type changes in a base class. Testing everthing is the best way to have a regression that is complete.
It doesn't hurt to write unit tests for your getters and setters. Right now, they may just be doing field get/sets under the hood, but in the future you may have validation logic, or inter-property dependencies that need to be tested. It's easier to write it now while you're thinking about it then remembering to retrofit it if that time ever comes.
in general, when a method is only defined for certain values, test for values on and over the border of what is acceptable. In other words, make sure your method does what it's supposed to do, but nothing more. This is important, because when you're going to fail, you want to fail early.
In inheritance hierarchies, make sure to test for LSP compliance.
Testing default getters and setters doesn't seem very useful to me, unless you're planning to do some validation later on.
well if you think it can break, write a test for it. I usually don't test setter/getter, but lets says you make one for User.Name, which concatenate first and last name, I would write a test so if someone change the order for last and first name, at least he would know he changed something that was tested.
The canonical answer is "test anything that can possibly break." If you are sure the properties won't break, don't test them.
And once something is found to have broken (you find a bug), obviously it means you need to test it. Write a test to reproduce the bug, watch it fail, then fix the bug, then watch the test pass.
As I understand unit tests in the context of agile development, Mike, yes, you need to test the getters and setters (assuming they're publicly visible). The whole concept of unit testing is to test the software unit, which is a class in this case, as a black box. Since the getters and setters are externally visible you need to test them along with Authenticate and Save.
If the Authenticate and Save methods use the properties, then your tests will indirectly touch the properties. As long as the properties are just providing access to data, then explicit testing should not be necessary (unless you are going for 100% coverage).
I would test your getters and setters. Depending on who's writing the code, some people change the meaning of the getter/setter methods. I've seen variable initialization and other validation as part of getter methods. In order to test this sort of thing, you'd want unit tests covering that code explicitly.
Personally I would "test anything that can break" and simple getter (or even better auto properties) will not break. I have never had a simple return statement fail and therefor never have test for them. If the getters have calculation within them or some other form of statements, I would certainly add tests for them.
Personally I use Moq as a mock object framework and then verify that my object calls the surrounding objects the way it should.
You have to cover the execution of every method of the class with UT and check the method return value. This includes getters and setters, especially in case the members(properties) are complex classes, which requires large memory allocation during their initialization. Call the setter with some very large string for example (or something with greek symbols) and check the result is correct (not truncated, encoding is good e.t.c.)
In case of simple integers that also applies - what happens if you pass long instead of integer? That's the reason you write UT for :)
I wouldn't test the actual setting of properties. I would be more concerned about how those properties get populated by the consumer, and what they populate them with. With any testing, you have to weigh the risks with the time/cost of testing.
You should test "every non-trivial block of code" using unit tests as far as possible.
If your properties are trivial and its unlikely that someone will introduce a bug in it, then it should be safe to not unit test them.
Your Authenticate() and Save() methods look like good candidates for testing.
Ideally, you would have done your unit tests as you were writing the class. This is how you're meant to do it when using Test Driven Development. You add the tests as you implement each function point, making sure that you cover the edge-cases with test too.
Writing the tests afterwards is much more painful, but doable.
Here's what I'd do in your position:
Write a basic set of tests that test the core function.
Get NCover and run it on your tests. Your test coverage will probably be around 50% at this point.
Keep adding tests that cover your edge-cases until you get coverage of around 80%-90%
This should give you a nice working set of unit tests that will act as a good buffer against regressions.
The only problem with this approach is that code has to be designed to be testable in this fashion. If you made any coupling mistakes early on, you won't be able to get high coverage very easily.
This is why it is really important to write the tests before you write the code. It forces you to write code that is loosely coupled.
Don't test obviously working (boilerplate) code. So if your setters and getters are just "propertyvalue = value" and "return propertyvalue" it makes no sense to test it.
Even get / set can have odd consequences, depending upon how they have been implemented, so they should be treated as methods.
Each test of these will need to specify sets of parameters for the properties, defining both acceptable and unacceptable properties to ensure the calls return / fail in the expected manner.
You also need to be aware of security gotchas, as an example SQL injection, and test for these.
So yes, you do need to worry about testing the properties.
I believe it's silly to test getters & setters when they only make a simple operation. Personally I don't write complex unit tests to cover any usage pattern. I try to write enough tests to ensure I have handled the normal execution behavior and as much error cases I can think of. I will write more unit tests as a response to bug reports. I use unit test to ensure the code meets the requirements and to make future modification easier. I feel a lot more willing to change code when I know that if I break something a test will fail.
I would write a test for anything that you are writing code for that is testable outside of the GUI interface.
Typically, any logic that I write that has any business logic I place inside another tier or business logic layer.
Then writing tests for anything that does something is easy to do.
First pass, write a unit test for each public method in your "Business Logic Layer".
If I had a class like this:
public class AccountService
{
public void DebitAccount(int accountNumber, double amount)
{
}
public void CreditAccount(int accountNumber, double amount)
{
}
public void CloseAccount(int accountNumber)
{
}
}
The first thing I would do before I wrote any code knowing that I had these actions to perform would be to start writing unit tests.
[TestFixture]
public class AccountServiceTests
{
[Test]
public void DebitAccountTest()
{
}
[Test]
public void CreditAccountTest()
{
}
[Test]
public void CloseAccountTest()
{
}
}
Write your tests to validate the code you've written to do something. If you iterating over a collection of things, and changing something about each of them, write a test that does the same thing and Assert that actually happened.
There's a lot of other approaches you can take, namely Behavoir Driven Development (BDD), that's more involved and not a great place to start with your unit testing skills.
So, the moral of the story is, test anything that does anything you might be worried about, keep the unit tests testing specific things that are small in size, a lot of tests are good.
Keep your business logic outside of the User Interface layer so that you can easily write tests for them, and you'll be good.
I recommend TestDriven.Net or ReSharper as both easily integrate into Visual Studio.
I would recommend writing multiple tests for your Authenticate and Save methods. In addition to the success case (where all parameters are provided, everything is correctly spelled, etc), it's good to have tests for various failure cases (incorrect or missing parameters, unavailable database connections if applicable, etc). I recommend Pragmatic Unit Testing in C# with NUnit as a reference.
As others have stated, unit tests for getters and setters are overkill, unless there's conditional logic in your getters and setters.
Whilst it is possible to correctly guess where your code needs testing, I generally think you need metrics to back up this guess. Unit testing in my view goes hand in hand with code-coverage metrics.
Code with lots of tests but a small coverage hasn't been well tested. That said, code with 100% coverage but not testing the boundry and error cases is also not great.
You want a balance between high coverage (90% minimum) and variable input data.
Remember to test for "garbage in"!
Also, a unit-test is not a unit-test unless it checks for a failure. Unit-tests that don't have asserts or are marked with known exceptions will simply test that the code doesn't die when run!
You need to design your tests so that they always report failures or unexpected/unwanted data!
It makes our code better... period!
One thing us software developers forget about when doing test driven development is the purpose behind our actions. If a unit test is being written after the production code is already in place, the value of the test goes way down (but is not completely lost).
In the true spirit for unit testing, these tests are not primarily there to "test" more of our code; or to get 90%-100% better code coverage. These are all fringe benefits of writing the tests first. The big payoff is that our production code ends be be written much better due to the natural process of TDD.
To help better communicate this idea, the following may be helpful in reading:
The Flawed Theory of Unit Tests
Purposeful Software Development
If we feel that the act of writing more unit tests is what helps us gain a higher quality product, then we may be suffering from a Cargo Cult of Test Driven Development.