Mocking in C# Unit Tests - How To Test Data Access Code and More
ฝัง
- เผยแพร่เมื่อ 9 ก.ค. 2024
- Unit tests are great, but how do you test your data access? You sure don't want to actually delete records when you are testing the delete method, yet you definitely want to be sure the method is configured properly. This is the type of problem that stops a lot of developers from creating unit tests. In this video, I am going to show you how to overcome these obstacles in order to write tests that handle working with external dependencies like databases.
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0:00 - Intro
1:05 - Getting started: demo application code and setup
10:20 - Problems with testing methods that manipulates with external stuff (database edits, e-mail senders etc)
12:39 - Mocking explained
15:44 - Writing tests with mocking
18:05 - Adding references for testing with MOCK
20:51 - Using statement
22:12 - AutoMock.GetLoose() vs AutoMock.GetStrict();
23:30 - Using AutoMock: Writing the Unit Test with mocking
35:06 - Refactoring method that's under a UnitTest
36:03 - Checking data: comparing two objects
40:19 - Testing method that returns void
48:16 - Testing SQl call modification
52:47 - Recap
53:30 - Advice for beginners
55:15 - What not to test and why
58:24 - Summary
59:27 - Learning steps
1:01:42 - Concluding remarks
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It had been a while since I finished watching a video with the excitement of having just learned something new and empowering. Thank you.
You are welcome.
I've watched 2 or 3 other training videos on this topic, and yours clears it up for me. Thanks!
I am glad it was helpful.
Damn you Tim You videos are amazing and so addictive , it's 4 AM here and i have work tomorrow. Thanks a lot for sharing you knowledge.
I'm glad you are enjoying them. Hopefully, you don't curse my name when you are at work.
I really like how your videos are segmented so that I can jump to a particular area by hovering over the progress bar.
Most of the videos are time tagged by volunteer students. Scroll down in the comments to see who did it and give them a shout out! They certainly deserve it (Hint: Ralfs)
Again you are coming in clutch! Another great video! I still find it quite hard to know how to use mocking in my tests I am supposed to write, but this definetly gave me a better idea about what mocking is, and now I mind be able to read the other tests and actually understand what is going on! Thank you!
Happy to help!
Have use Moq testing today, since we're starting to implement this framework within our product. Thanks to this video, it didn't take me long to create unit tests.
Excellent! I am glad it was helpful.
Thanks, Tim!
Always good value content!
You are welcome.
Awesome tutorial !! Thank you once again for sharing this Tim.
You are most welcome. Thanks for watching.
0:00 - Intro
1:05 - Getting started: demo application code and setup
10:20 - Problems with testing methods that manipulates with external stuff (database edits, e-mail senders etc)
12:39 - Mocking explained
15:44 - Writing tests with mocking
18:05 - Adding references for testing with MOCK
20:51 - Using statement
22:12 - AutoMock.GetLoose() vs AutoMock.GetStrict();
23:30 - Using AutoMock: Writing the Unit Test with mocking
35:06 - Refactoring method that's under a UnitTest
36:03 - Checking data: comparing two objects
40:19 - Testing method that returns void
48:16 - Testing SQl call modification
52:47 - Recap
53:30 - Advice for beginners
55:15 - What not to test and why
58:24 - Summary
59:27 - Learning steps
1:01:42 - Concluding remarks
Thank you! I have added it to the video.
even thou I use Nunit for testing, but this video helped me quite a bit. Thanks a lot. Yours are good, cause you not only show HOW - but you tell WHY. Pretty rare on youtube I say. Thanks again!
You are welcome.
Tim, I really admire you the way you explain the things. I remember ignoring this lesson in 2018, but today I came back to the very same tutorial. Happy to learn from you Tim Thanks
You are very welcome! I like to hear about students being able to search the channel and find just what they need when they need it.
Thank you!!! Great tutorial on Mocking!!! Got the first of many written. Awesome!!!
You are welcome.
Thanks for making a complicated subject easy to understand. You have a real talent for teaching!
Thank you.
This is fantastic. Extremely relevant to what I am currently working on. Thank you!
I'm glad it is so relevant to you. Thanks for letting me know.
I've been searching for a while a good content for tests in Microsoft environment and now I found a good explanation. Finally I understand the reason and how to test void and CRUD methods.
Excellent!
Beautifully explained with calm voice. So good!
Thanks for trusting Tim for your learning
I'm always thankful for your efforts.
You are welcome.
You the man TIm! My go 2 for C# learning. Cheers
Thank you!
Very informative! Thank you for all the effort, I'm sure, went into making this video!
You are welcome.
Hey Tim,
Great video as usual. There's absolutely no reason you should be getting any thumbs down. There are those who know how to code really well but don't know how to teach, but you can do both hands down.
Thank you for giving back to the community.
I appreciate the kind words.
Kind of. The tutorial is very good... if you're using AutoFac, or some kind of Dependency Injection.
I'm modding a game, and need to mock some of the supplied API for testing offline. I understand what mocking is, but I don't use AutoFac. The first 18 minutes of the video were explaining the project architecture, the basics of unit tests, and the difference between tests that don't need mocking, and those that do. We then install Moq, and AutoFac.Extras.Moq. We then move on to only show the AutoFac features of Moq... not an overview of how to use Moq in its own right.
If you don't use Dependency Injection, or you are just starting on the road to learning how to use a Mocking framework, this video doesn't teach you as the title says it will. This was the reason for my Thumbs Down... I felt that the title and thumbnail were misleading, compared to the content, regardless of how well that content was presented. This missed the first ten rungs of the ladder. For an introduction to Moq, it would be better to use Moq in isolation, and then teach AutoFac.Extras.Moq as a follow-on video, clearly stating ("With AutoFac") within the title and/or thumbnail of the video.
I've been trying to follow along, but I don't have an AutoMock class, and Mock isn't IDisposable, so I can't scope it within a using block.
Really good video. Thanks for making it easy, Tim!
You are welcome.
Thank you so much for this clear and concise explanation..
I tried learning mocking from a book a year back but never understood it that time.. i thought I should give it a try one more time..
Now I Finally know what mocking is ..
Thanks again..
Happy to help
Thank you so much for all your videos I can't stress enough the amount of gratitude I, and I'm sure the rest of us, have for you, so truly thank you.
You are welcome.
@@IAmTimCorey I have a question regarding mocking here for the LoadData method.
Is it true that it's better to use object parameters instead of dynamic parameters because it creates issues in mocking?
for example to use
___
LoadData(string sqlStatement, object parameter, string connectionStringName, bool isStoredProcedure = false)
___
instead of
___
LoadData(string sqlStatement, U parameter, string connectionStringName, bool isStoredProcedure = false)
I really needed to refresh this today. Thanks you. and keep it up!
Good Explaining!
Excellent! Glad I could help.
I loved this video! Thanks again Tim
You are welcome.
Thanks man! Yet another great tutorial. I get more and more Inout for my new project!
Cool!
Tim, thanks for the effort. Well done.
Thank you!
Im also loving the live code coverage feature. Good to know about that too! You have helped me really much again. Tomorrow i will watch your vid about Autofac
Great!
Thanks Tim! .. from Neuquén Argentina. It is a very good and illustrative video.
You are welcome.
Having watched your video on Unit tests yesterday; I started this video thinking how I missed the suspense of having to actually click run tests to get a green (or red) check mark. But man, the convenience enterprise provides is great! Will definitely have to look into those third party options for auto testing.
Great video Tim, I know I'll be returning to watch again in the near future =]
Excellent!
This is the kind of video that I'll never be able to finish watching. Kept falling asleep, then rewind back to watch again but fall asleep again. I've rewinded about four times this afternoon. 😂
Watch it at night so you at least get a good night’s sleep out of it.
@@IAmTimCorey 😄😄😄😄
when i first learnt abt tim i shared the same behavior you had. however, as time passes, i realize that i am using the wrong method. instead of watching the video, which is comprised of tons of new information, in a row, i should watch them bit by bit, namely
1. watch 5 more minutes
2. conclude what i have learnt
3. if i feel comfortable, go back to 1
4. otherwise, re-watch
hope this helps
That means you do not give up easily- that’s good
Story of my life. I go to a beach 🏝️ or mountain 🏔️ shopping center it’s not easy but his vids are the best
Thank you Tim you are helping me a lot.
You are very welcome
I appreciate you Tim!
Thank you!
really good video, as always!!!
Thanks!
great video, thanks a lot Tim
Glad you enjoyed it
Thanks for showing me a whole new world, shining, shimmering, splendid...
You are welcome.
Always top notch.
Thanks
Another great tutorial!!
Thanks!
Thanks tim for more new stuff
You are welcome.
Great video Tim
Thanks!
You saved my life once again :)
Good to know.
thanks for the great video, as always
what do you do if you want to test a class that doesn't implement an API?
do you have to "force" it into implementing one?
another great video!
Thank you.
Tim, this was a good video. I was a bit hesitant about mock frameworks as I am a firm believer in writing all code when it comes to unit test. That's the way I was taught in the 90's. I watched your video several times and then it clicked it my thought process on how you used moq framework and more importantly why. I had to think back on how I wrote all the extra code to test to realize how this can cut down on writing so much of it before being able to find bugs. Thanks for a great video, I do appreciate this and look forward to watching more.
Awesome! I'm glad the video was able to help clarify somethings for you and improve your process.
Thank you for showing the code behind the class SqlLiteDataAccess at 55:30. Wow, Dapper is awesome! Great Video!
I definitely agree that Dapper is awesome. I'm glad you enjoyed the video.
Dapper supports async fully so I would recommend making your class async as well.
I really like your advice, and autofac is so nice. Not have to click run every time you update your code is so convenient. Thank you for the content.
You are welcome.
Hi Tim,
Thanks a lot for such a wonderful video. I appreciate your advices and sharing with us how you work (for example how far do you go with test coverage). Is there any tool/platform that you would recommend for analysing test coverage, code smells, etc (i.e. sonarqube)?
I don't really have a tool beyond what Visual Studio provides. They have some great features for test coverage, test running, etc.
Thanks for the video. What are my options for Live Testing if I only have Visual Studio Community 2022? This live testing tool is very handy
Great Video!!!
Thanks!
Using this getloose, to test a method that is returning a connection string, that is located in a library is a good way? Or should i do it in another way, because i cant figure it out.
PS: this method used dependency from IConfiguration
This was of great help for my project, Thanks Corey! By the way, how would you setup your LoadPeople call if you are using LoadData multiple times with different querystrings within LoadPeople (let's assume thats a valid use case)
First: Thankyou for all your videos! I love them!, I am learning a lot thanks to them.
Second: Does the base code that you use in the video belong to any of your published courses?
No, it does not.
How can we mock Httpcontext of a mvc controller. I am trying to test a action method where i am getting session variable null all the time while unit testing.
Great video. Very addictive channel.
Thank you!
Thanks sir for this great video.
You are welcome.
Thanks Tim.
You are welcome.
I am using the IDataAccess (DataLibrary) you made in another video, but I got a System.NullReferenceException on the actual list in the unit test.
How does the unit test (especially the setup) look like if using the DataLibrary from your video "Connecting C# To MySQL Using Blazor"?
I am not directly returning the output, but putting it in a global list and return it in a getter method.
Hello Tim. Another good video. After digging, I found that Moq appears to be the industry standard for mock-ing (based on the nuget download count). So, even though the video is nearly 2 years old, the framework is still good to get familiar with.
Yep, it is a pretty popular framework.
Hi Tim! I have been a big fan for a long time. Always recomend your videos to my friends.
A year ago I switched jobs and now I am working with Spring Boot instead of C#. And right now we are debating using H2 as a in memory database for testing.
I would love to hear your thoughts about it. I always heard you should not use a database for testing, but at the same time is nice to know that our repositories are working and the db contrains are working as well.
Thanks in advance!
Amazing course
Thanks!
Thank you for the amazing content, Tim. I have been following you for quite some time and I always learn a few things from your videos even when they cover topics that I am already familiar with. Just wondering what your thoughts are on Test Driven Development. Is it something that you practice in the projects that you work on? I am looking to learn more about it. I would be most grateful if you can cover it in a video sometime. Thanks again. :)
Thanks for the suggestion. Please add it to the list on the suggestion site so others can vote on it as well: suggestions.iamtimcorey.com/
If you are using SQL Server not Sqlite (ISqliteDataAccess) what Interface file do you use and where can I get it? Thanks in advance.
Is Moq a good choice for mocking integration tests? For example, if a method calls two methods: 1) read a mocked thermometer and returns the value and then 2) the value is checked against limits and returns a bool value.
It sounds like you are doing unit testing there, not integration testing. Integration testing is usually about testing the interaction of multiple things. You can still use moq for it if you want to put a boundary around the test, though.
Hi Tim,
This line seems to be failing. mock.Create(); I have photoservice class that implements dependency injection which its constrcutor seems bit like this
private readonly PhotoEntities _context;
public PhotoService(PhotoEntities context)
{
_context = context;
}
Any idea how I should get around? thanks.
You would need to pass the instance in to the constructor so it would look something like mock.Create(yourPhotoEntries instance);
qq for initial set up for mocking & xunit i have got the error " response status code does not indicate success: 403(Forbidden).
That's a permission issue (a 403 error).
I love the stuff with Moq, but due to the fact that extension methods are not supported, when you want to mock the ILogger it becomes a real mess (LogDebug, LogInformation are extension methods) :(
You can only use the plain Log method, which is quite impractical.
What is your opinion on this?
Interesting video Tim, I am curious first can you moq without dependency injection, specific for extension which is based of WPF.
That is harder to do, since it is a hard dependency.
Thank you very much Tim, really helped me to learn @~>. Keep on the great content!
You are welcome.
nice, thanks
You are welcome.
Hi, Tim. After all i just have one question. would it be a good idea to extract ConvertHeightTextToInches and ValidateName methods into different classes, so that PersonProcessor could adhere SRP? i.e. the rules being used to convert HeightText to Inches could change and we don't want to change PersonProcessor because of that.
Those would be things to consider. It depends on your application size and what you are attempting to do, but probably yes.
Hi Tim, how the test at minute 51 realize, that the sql is wrong with the integer value?
When we passed in our known values, we knew what the resulting SQL string should look like. When it did not look the way we expected, we knew we had an issue. It compared the two strings to be sure they were the same. They weren't. Therefore, our expectations did not match our code's reality.
In my project I use Moq/Xunit and Dapper/DynamicParameters...
If I don't use DynamicParameters my test works, but if I use DynamicParameters, my mock object just returns null???
If I just rund the code with DynamicParameters everything works fine and I get data back from my test DB
Do you know a workaround to solve the problem with Dapper/DynamicParameters in unit testing?
This work for me.
mockdb.Setup(x => x.DbQueryAsync(
"USP_S_Test_Get",
CommandType.StoredProcedure,
It.IsAny()))
.Returns(GetTestIEnum());
var cls = mock.Create();
var actual = cls.Get(testCode);
I wanted to ask how to go about applying testing to following scenario in following .NET Core App:
Class A is a Background service that consumes a message from a Rabbit queue.
Class B is a "MessageProcessor" class. It has a public method.
This method makes a call to a private method that invokes a public method of Class C. So Class B has a dependency on Class C.
Class C is a class that makes REST API call to an external API.
Do I have to put all 3 classes under separate tests or does it depend on what to test/what I should be testing?
So if I wanted to test the behaviour of processing a message I would put Class B under test and mock it's dependencies appropriately.
My current understanding is that I should be testing specific behaviour. Is that right?
One thing I might ask you Tim, at 47.00 You're talking about how to test the VOID methods, but the explanation you gave was about just calling the void method 'certain number of times' not exactly the void function execution / catching at test-phase
In order to test more than just that the method fired, the method has to change something that you can test. Unit testing is about testing effects. So, you need to find an effect to evaluate.
Great video Tim thanks. Never really done any unit testing as the firms I've work at don't seem to do them, so never really got into them. AutoFac... Looks like I missed a video - DI With AutoFac - YT seems to think I've watched it. I'll have to go and watch that now as I had no idea what AutoFac is.
It is definitely a good one to learn.
thanks for theexcellent video. Can you please tell me how to test a data layer function which calls stored procedure? Your eg shows simple queries but how do i test a function which calls SP
Check to make sure it makes the call (mock the actual item it is calling) and make sure the inputs are correct for what you expected.
@@IAmTimCorey cool..but am little confused because how do i mock command object. Eg IDbCommand command = GetCommand(con)) {command.comandText="someSPName"}.
what is confusing me is how do i mock the spname..like syntax etc...can u please provide an eg if possible
Is there a way to mock a database and send stuff to it? For my school project I have to make a web application where 90% of everything is either sending things to or receiving things from an SQL database. Most of my methods and classes revolve around doing something with the database however knowing if the code ran isn't enough to say if the test was successful. The code might have ran but the user it added misses half of the info he should have gotten. So I wanted to ask if there is a way to mock a database, send something to it and then checking if what was send was correct?
How you do that is to separate your writing to the database from your business logic code. I do that in the TimCo Retail Manager series. There is a class that has a Read and a Write method for SQL. Then I have other classes for figuring out what to read and write. I can test those and mock the data access methods (read/write) easily.
Hey Tim, great content as always. I was hoping to find a full unit test course on your site! I'd be a day-1 customer if you manage to put one together.
In any case, I was hoping you might be able to help with some simple guidance if you don't mind.
I understand mocking within the context of unit tests, but I'm wanting to mock service calls for my ViewModels that ultimately the UI binds to. Basically, I have a ViewModel that makes a service call, which hits a database and (for example) returns a list of people, in my view I have a DataGrid that binds to the results in the ViewModel. No problem. What I want to do is instead of hitting the actual database I'd like to return mocked objects.
I have cobbled something together manually that handles this, but can you shine some light on best practices with this type of scenario? Basically what I'm doing now is I have a dummy service (both the dummy and actual service implement the same interface) and the dummy service (manually) mocks up service calls and results. I'm using dependency injection to determine which service I'm actually going to use.
Does this sound like a decent approach? Any guidance is greatly appreciated!
Yep, that works. You can use Moq to make the dummy service though.
HI Tim,
Very informative , this will help me in some way.
I am facing some issue in mocking like I have created one integration Test based on CRUD operation but it was talking to real data ..how to mock this integration test (mock request response to create data and than update and delete it.
The principle is the same as what I covered in this video.
@IAmTimCorey -- I have a Generic-based data handler interface and associated services which I am trying to mock calls for. However, anytime I run a test, I get a NULL value from any calls to the Generic data handler. If I run the code in Production, the calls work, so I do not believe it is an issue with the way I have my services written. Any ideas what causes this kind of issue with Moq? NOTE => I am using the following NuGet Packages, in case they are the issue:
AutoFac / AutoFac.Extras.Moq = 4.1.0 / 4.2.0
XUnit 2.4.1
Moq 4.13.1
My thought is it might be an issue with AutoFac and Moq, as I already had to go back multiple versions to get Moq/AutoFac to even play well together, as it was previously failing on `var mock = AutoMock.GetLoose()`
This seems simliar to what another user below in the comments is seeing, where your code's `cls.LoadPeople()` call is returning null for them, but not others.
Thanks for the videos, they are most helpful when trying to learn new concepts (I am an older programmer, and mocking is not something we did in most other jobs I have held).
Not sure what the specific issue is but it sounds like a setup issue. Maybe run the test in debug mode and step through the code.
Hi Tim Corey,
Hope you're doing well. I watched your all video series it help me alot in real time.
I'm struggling for writing unit test using xunit framework. One for the method is inserting records into SQL db. I have written unit test case for this method but in the end cmd. executenonquery throwing exception like below
"BeginExecuteNonQuery requires an open and available connection. The connection currently state is closed"
I believe I need to mock sqlconnection any suggestions from your end. Appreciated
The first step is to identify what logic you are trying to test. Are you testing that the insert method is called or are you trying to test that the record was inserted? Unless your insert method is performing some logic, it does not need to be tested. If it is doing some logic on the inserted data, separate that logic from the actual insert (single responsibility principle) and then test just the logic method.
@@IAmTimCorey great to here thank you for your quick response,
I'm trying to test valid/invalid dummy data inserting into db but without hitting db it's should work till now no luck. I think I'm not sure I need to add config file into my test project and then i need to mock it.
Please suggest is that right way I'm think?
Again Appreciated..!
Hi Tim,
How to appear green tick pass or red fail when unit test.
Thanks very much!
That is a Visual Studio Enterprise feature (I talked about it briefly in this video). It is called Live Unit Testing.
The feature is only available in Enterprise edition of visual studio
Hi Tim, love your videos. I am a junior - mid level software engineer trying to bring some implementation tests to my company. We use entity framework with a database for each of our clients where each DB has the same table structure (same tables and columns within those tables across all dbs). Do you have any suggestions on what framework/Design pattern to use to achieve this?
Sorry, I'm not sure I understand. Are you saying you want to do implementation testing on your clients' installations? If so, that sounds like something you want to build custom since it is post-deployment.
Just a question, how do you handle Winform objects with autofac. I have manager/processor classes registered in autofac that will have to update winform ui but since i created the ui elements using winform designer, they are not registered with autofac. And I hesitate to touch any code made by the designer. One way is to pass the winform ui as arguments everytime i use a method but that feels tedious especially if the processor class is design specifically to update a certain winform ui element.
Every object that you instantiate, including Winforms windows, needs to be registered in Autofac. If you do manual instantiation, you negate the purpose of dependency injection. You won't need to touch designer code, though.
@@IAmTimCorey Lets say I have two projects FormsUI and FormsLibrary where FormsUI depends on FormsLibrary. I have a listboxmanager class in formslibrary that requires a listbox reference from FormsUI. How do I tell autofac to pass the reference of the listbox object created in FormsUI designer to the listboxmanager.
If your library has that tight of an integration to the UI, it isn't really a separate library. It is part of the UI layer.
Hi Tim,
I have a question if you got time for it:
I am trying to mock a SshClient part of Ssh.Net library which I don't have control over. The part giving me problems is that this SshClient does not implement any interface so I will have direct dependency on it. What is the best way to handle this issue?
You have a couple options. The best option is if you can isolate the calls to that library in a wrapper class that you can control (and create an interface for). You don't need to unit test the SshClient itself, just the code that uses it so you can mock it where it is relied on. The other option is to use a Fake to replace it (not nearly as clean).
Dear Tim,
One small Thing: Our database structure changes sometimes. How can i test if the the Database Structure matches my Model?
You could wrap it in your own class that you can unit test.
Hey Tim, love your videos.. I like how you explain things. One question, my project test doesn't run at all. It does spin but at the end it just says something like "0 tests ran, 0 tests failed, 0 tests skipped." Also, the test says "Excluded from Live Unit Tests" and I'm right-clicking and choosing "Include...." doesn't seem to have an effect. Thanks!
Not sure why you are getting that issue. It sounds like something isn't configured properly but I don't know what that might be.
@@IAmTimCorey Well, I forgot to add the xunit.runner.visualstudio.. Oops.. Thanks for replying Tim!
Hello Tim, how do I turn on the check marks in my Visual Studio Enterprise? Thanks!
In the Test menu, turn on Live Unit Testing.
This feature is called Live Unit Testing in visual studio and its only available in the Enterprise edition
Liked video before watch 😄I know it will going Perfect
Thank you!
Hey, Tim.
I'll be testing this in a personal project I have in development.
But first I need to know something about the connection string best practices...
In a scenario like the one you show, where would you put it? In the UI project or in the library itself?
I understand you're using Sqlite so I guess it kind of maps itself (?). Never used it as I prefer to have an actual database, whenever possible.
My point is... I created an appsettings.json on a consoleUI, where I'm testing the actual inserts to the database to check if they're working correctly.
And in the library on getting the connection string. I know I should have both on one side only, but which side?
It makes sense to me to have them in the library, but I think I've read somewhere we shouldn't do that, for some reason...
I need to know, from your experience, what's your take on this?
We store the connection strings in the appsettings.json file (or app.config/web.config if you are on .NET Framework). Those files are associated with front-end project types (Console, WinForm, WPF, ASP.NET Core, etc.) We put the connection string in the front-end because then the front-end dictates the database that the library will use. This is useful because we can reuse the library in multiple projects with different database locations (even if it is the same database structure it will live in different locations).
@@IAmTimCorey that was my thought.
But then there's the case that someone that will implement another UI forgets about connection string setup for some reason or names it differently.
Anything we can do about that aside from just letting it throw an exception? Or is it better to just let it blow up?
This is a great video, thanks for sharing.
I had to make one small tweak to the code to get the last test to run:
public void SavePerson(PersonModel person)
{
string sql = "insert into Person (FirstName, LastName, HeightInInches) " +
"values (@FirstName,@LastName, @HeightInInches)";
I had to remove the space between @Firstname, @Lastname because my values for the string sql would not match
example:
sql
"insert into Person (FirstName, LastName, HeightInInches) values ('Tim','Corey', 80)" (SavePeople_ValidCall method value)
sql
"insert into Person (FirstName, LastName, HeightInInches) values ('Tim', 'Corey', 80)" (SavePerson method value)
Interesting.
Any resource on how to Moq a foreach loop in c#?
Added to my growing list of possible future topics.
How may Assert Statment is good to have in one test case? Is it good to have multiple?
I'll give you my opinion (there are some differing ones). I personally do as many asserts as needed to verify a test case. If a method changes three values in an object, I will usually test all three. Some people think that this should be three tests. I disagree because it is one action. So, I do as many asserts as necessary to verify that the state that has changed is as I expected.
Awesome video. Can you please help with ADO.Net + Repository pattern + Unit testing in .Net core? Only quick sample is enough. I am facing issues with mocking stored proc and proper repository arrangements. Thanks.
I will add it to the list. Thanks for the suggestion.
1+
Hey Tim!! any chance you can update this video to the latest version of Moq?, this one aged really bad, right now Moq is not required to use "using". Thanks!
Thanks for the suggestion. Please add it to the list on the suggestion site so others can vote on it as well: suggestions.iamtimcorey.com/
@@IAmTimCorey Done!
Hi!, Great videos about testisng. One question, do you have any video to learn how to effectively moq Entitify framework DbContext and DbSet that can be seen as Unit of work and Repository pattern? Perhaps it is better in this case to use a real database in memory like localdb, memorydb o sqlite on memory?
I don't have a video on that, sorry. It can be tricky to mock these.
As Tim said, it is difficult if not impossible to directly mock EF native classes.
What I have done before is abstract/wrap all of EF, so that in business logic we never reference any EF objects/types directly.
Instead all access is done through our own wrapping interfaces and class implementations that contain all our CRUD business logic etc.
Then all of these interfaces and types can be injected as per usual, and then easily tested and mocked etc.
For example:
// Generic base interface to represent a repository/set of any entity type T. Also supports IEnumerable, IQueryable etc.
interface IRepository : IEnumerable, IQueryable {
IEnumerable GetAll(); T GetById(int id); T Add(T new); T Update(T changed); void Delete(T); void Delete(int id); // Etc...
}
// Generic base implementation of the Repository interface using EF DbSet (in a DbContext). Again generic type T is an entity type.
public abstract class Repository : IRepository {
protected readonly DbSet _dbSet;
public Repository(DbSet dbSet) { _dbSet = dbSet; }
// Includes base implementation for IQueryable & IEnumerable; most else abstract. ....
}
// Example of specific repository interface for a repository/set of Persons, and extends the generic interface above.
interface IPersonRepository : IRepository { ... void MyCustomMethod(); ... } // Can also add extra custom methods here
// Example of specific class implementation of a repository/set of Persons using EF DbSet (in a DbContext).
public class PersonRepository : Repository, IPersonRepository {
public PersonRepository(DbSet dbSet) : base(dbSet) { } //...etc
public Person GetById(int id) { return _dbSet.FirstOrDefault(x => x.Id == id); } //...etc
public void MyCustomMethod() { /*Does Something*/ }; //...
}
// IDataContext interface with a get property for every repository/set class for each type of entity.
interface IDataContext { //...
IPersonRepository Persons { get; }
//... all other repository/entity types...
}
// Implementation of IDataContext using EF DbContext and EF DbSets etc. All repository/set properties use lazy init.
public class EFDataContext : IDataContext {
private DbContext _dbContext; // Can inject EF DbContext or instantiate in ctor etc.
//...
public virtual IPersonRepository Persons { get {
if (_persons == null) _persons = new PersonRepository(_dbContext.Persons); // Lazy init with EF DbSet.
return _persons;
} }
private IPersonRepository _persons; // Field for lazy init.
// Repeat pattern for for all entity types...
}
We did nearly of this using code-generation from EF T4 templates, similar to how EF POCO entity data model classes are created out of the box.
We extensively modified these T4 templates to also create/update all the extra interfaces and repository classes, which is absolutely necessary for 200+ entity types.
But if you only have a few entity types this could be done by hand fairly quickly. You would probably also want to make use of partial classes, so you can code-gen half the Repository into one
Obviously the code in the EFDataContext class cannot be unit tested, but it doesn't need to be since it is code-generated.
Then you can pass/use only IDataContext and IPersonRepository (etc) in your business logic, all of which can be easily mocked and tested.
Also then you can entirely swap out EF with a different ORM if you wanted to as well, since we've basically created a generic ORM interface.
However the code generation (in our case) was coupled with the EF code gen and the EF EDMX model etc.
Hello Sir , thank you for all tutorials. Also , if you can make intermediate Web api project from scratch, it would be perfect for us. ( I finished your Web api tutorial and it was awesome. That's why I wanted one more full project :) )
Thank you again for your all videos Sir.
It is on the agenda. Thanks for the suggestion.
I´ve had some trouble trying to do unit tests for some services that contain extension methods. any suggestions to handle this kind of scenario?
what kind of troubles where these?
for some reason I thought mock tests were something more closely resembling integrated tests but I was wrong
I feel like this is not the best way to test things related to database, which just enforces you to check your input twice instead of actually checking the output
for complex enough queries, it pains me to say but I guess I'll just have to stick to the real thing in docker with proper setup and teardown of tests
Thanks for watching
Hi Tim, I am trying to combine the mocking with many other areas. But get a little stuck. In one of your other videos you have a line with something like:
var x = await _sqlDataAccess.LoadData(usp, new { LanguageID = LanguageId });
This is kind of a combination of my classes with your logic. It looks like that dynamic is not supported by moq and xunit. With I replace it here with a single int it works. But that brings too much restrictions to use this line for other options. So, I thought to replace it with a List but then again it doesn't work.
I am doing debug test and at the time it should give me back a result from the Mock it shows Null.
Also I was thinking if I bring the parameter maybe as a tuple into the dataAccess class and convert it there to an List
The project that I am working on are in .Core 3.1 and the test project is .Net standard 2.0
I believe it should support dynamic but if it doesn't, you can always create your own mock manually of the sqlDataAccess class. Just create your own class that implements the interface and put your mocked code in the methods.
@@IAmTimCorey thanks, will have a look at it. Just doing some other things at the moment. You will see another reply in another video for that.
Hi Tim,
If you are bypassing the code of SQLLiteDataAccess class than why do we need the moq library for mocking.
We can simply have two classes implementing ISQLDataAccess where one would return the actual data from DB and the other mock class will return the mock data.
So we can create our app context at the starting of our app where all the interfaces would have the actual data access classes and from the testing project the context interfaces will have the mock classes
Here using moq requires lot of code to be written as well as adding a library in your project
Correct me if I'm wrong
What you are proposing is to write a class to mock the implementation. That is what Moq does for you in a more dynamic manner. It allows you to make a simple mock (you don't have to mock everything, just what you are using) and it allows you to change the output values to test various scenarios (something your actual implementation would have a harder time doing).
@@IAmTimCorey Hi Tim,
We can also achieve testing different scenarios using mock classes and return the output on the basis of some reference IDs.
By using mock classes all the mock return code would be in mock classes and our unit test functions would have just assertion code.
In moq we need to write objects of moq classes than use create setup functions
All these code isn't required.
I have implemented the mock classes in my company although I can't share the code but I will write some short demo code and will present that to you in sometime.
With moq you can configure it to return different data for different scenarios. Therefore there is greater flexibility than if you hardcoded a result into a class and you won’t end up with loads of classes you have created to use in a single test. Having said that I do use a fake class in many cases when I just need an instance and I am not testing it.