I'm currently working a MVC 5 project using Entity Framework 5 (I may switch to 6 soon). I use database first and MySQL with an existing database (with about 40 tables). This project started as a “proof of concept” and now my company decided to go with the software I'm developing. I am struggling with the testing part.
My first idea was to use mostly integration tests. That way I felt that I can test my code and also my underlying database. I created a script that dumps the existing database schema into a “test database” in MySQL. I always start my tests with a clean database with no data and creates/delete a bit of data for each test. The thing is that it takes a fair amount of time when I run my tests (I run my tests very often).
I am thinking of replacing my integration tests with unit tests in order to speed up the time it takes to run them. I would “remove” the test database and only use mocks instead. I have tested a few methods and it seems to works great but I'm wondering:
Do you think mocking my database can “hide” bugs that can occur only when my code is running against a real database? Note that I don’t want to test Entity Framework (I'm sure the fine people from Microsoft did a great job on that), but can my code runs well against mocks and breaks against MySQL ?
Do you think going from integration testing to unit testing is a king of “downgrade”?
Do you think dropping Integration testing and adopting unit testing for speed consideration is ok.
I'm aware that some framework exists that run the tests against an in-memory database (i.e. Effort framework), but I don’t see the advantages of this vs mocking, what am I missing?
I'm aware that this kind of question is prone to “it depends of your needs” kind of responses but I'm sure some may have been through this and can share their knowledge. I'm also aware that in a perfect world I would do both (tests by using mocks and by using database) but I don’t have this kind of time.
As a side question what tool would you recommend for mocking. I was told that “moq” is a good framework but it’s a little bit slow. What do you think?
Do you think mocking my database can “hide” bugs that can occur only when my code is running against a real database? Note that I don’t want to test Entity Framework (I’m sure the fine people from Microsoft did a great job on that), but can my code runs well against mocks and breaks against MySQL ?
Yes, if you only test your code using Mocks, it's very easy for you to have false confidence in your code. When you're mocking the database, what you're doing is saying "I expect these calls to take place". If your code makes those calls, it'll pass the test, but if they're the wrong calls, it won't work in production. At a simple level, if you add / remove a column from your database the database interaction may need to change, but the process of adding/removing the column is hidden from your tests until you update the mocks.
Do you think going from integration testing to unit testing is a king of “downgrade”?
It's not a downgrade, it's different. Unit testing and integration testing have different benefits that in most cases will complement each other.
Do you think dropping Integration testing and adopting unit testing for speed consideration is ok.
Ok is very subjective. I'd say no, however you don't have to run all of your tests all of the time. Most testing frameworks (if not all) allow you to categorise your tests in some way. This allows you to create subsets of your tests, so you could for example have a "DatabaseIntegration" category that you put all of your database integration tests in, or "EndToEnd" for full end to end tests. My preferred approach is to have separate builds. The usual/continuous build that I would run before/after each check-in only runs unit tests. This gives quick feedback and validation that nothing has broken. A less common / daily / overnight build, in addition to running the unit tests, would also run slower / repeatable integration tests. I would also tend to run integration tests for areas that I've been working on before checking in the code if there's a possibility of the code impacting the integration.
I’m aware that some framework exists that run the tests against an in-memory database (i.e. Effort framework), but I don’t see the advantages of this vs mocking, what am I missing?
I haven't used them, so this is speculation. I would imagine the main benefit is that rather than having to simulate the database interaction with mocks, you instead setup the database and measure the post state. The tests become less how you did something and more what data moved. On the face of it, this could lead to less brittle tests, however you're effectively writing integration tests against another data provider that you're not going to use in production. If it's the right thing to do is again, very subjective.
I guess the second benefit is likely to be that you don't necessarily need to refactor your code in order to take advantage of the in memory database. If your code hasn't been constructed to support dependency injection then there is a good chance that you will need to perform some level of refactoring in order to support mocking.
I’m also aware that in a perfect world I would do both (tests by using mocks and by using database) but i don’t have this kind of time.
I don't really understand why you feel this is the case. You've already said that you have integration tests already that you're planning on replacing with unit tests. Unless you need to do major refactoring in order to support the unit-tests your integration tests should still work. You don't usually need as many integration tests as you need unit tests, since the unit tests are there to verify the functionality and the integration tests are there to verify the integration, so the overhead of creating them should be relatively small. Using categorisation to determine which tests you run will reduce the time impact of running your tests.
As a side question what tool would you recommend for mocking. I was told that “moq” is a good framework but it’s a little bit slow. What do you think?
I've used quite a few different mocking libraries and for the most part, they are all very similar. Some things are easier with different frameworks, but without knowing what you're doing it's hard to say if you will notice. If you haven't built your code with dependency injection in mind then you may have find it challenging getting your mocks to where you need them.
Mocking of any kind is generally quite fast, you're usually (unless you're using partial mocks) removing all of the functionality of the class/interface you're mocking so it's going to perform faster than your normal code. The only performance issues I've heard about are if you're MS fakes/shims, sometimes (depending on the complexity of the assembly being faked) it can take a while for the fake assemblies to be created.
The two frameworks I've used that are a bit different are MS fakes/shims and Typemock. The MS version requires a certain level of visual studio, but allows you to generate fake assemblies with shims of certain types of object that means you don't have to pass your mocks from your test through to where they're used. Typemock is a commercial solution that uses the profiling API to inject code while your tests are running which means it can reach parts other mocking frameworks can't. These are both particularly useful if you've got a codebase that hasn't been written with unit testing in mind that can help to bridge the gap.
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I'm working for a Flutter App which relies on an API. We are thinking about a testing strategy and we would like to know which should be the best approach.
According to their documentation ( https://flutter.dev/docs/testing ) they have 3 levels of tests:
Unit tests
Widget tests
Integration tests (Pump widgets new approach)
Integration tests (Flutter driver old approach)
As we have limited resources, we would like to know what we should pickup first. Since until now, very few effort was put on testing.
Our situation is the following:
Unit tests (50% coverage)
Widget tests (0% coverage)
Integration tests (Pump widgets new approach - 0% Coverage)
Integration tests (Flutter driver old approach - Only a few test scenarios covered, the main flows)
API Tests: 0% coverage on unit tests and functional tests
And we are not using any testing automation framework such as WebdriverIO + Appium.
We would like to know how much effort we should put in each of the Flutter test categories, and regarding Flutter integration tests, would it make sense to just have Integration tests with the new approach (Pumping every widget) or we would also need Integration tests (Flutter driver old way)?. Relying only on the integration testing using pump widget approach doesn't make us feel very confident.
Some options we are considering are:
Strong API coverage (unit test and functional test) + Strong coverage on Flutter unit tests + Few Integration tests using flutter driver approach
Testing pyramid approach : Lots of unit tests + Less amount integration tests using pump widget new approach ,API tests and Widget tests + Less amount of E2E tests (maybe using Integration tests using flutter driver approach or an external automation framework) and manual tests
Just unit test + Widget test + Integration tests the new approach of pumping widgets, trying to achieve 100% coverage in each of the three.
We also think that maintaining integration tests the new way (pumping widgets) is somehow very time consuming as you need to have good understanding of the views and the internals of the App. Which might be challenging for a QA Automation guy who hasn't got too much experience with Flutter development.
Which of the Flutter automated testing categories I should cover first, unit, widget or integration testing? Should I use an external automated framework such as WebdriverIO + Appium instead?
First, at this moment, I would suggest to think about testing in the application perspective, not on Flutter, React-native or Native perspective, well, test pyramid and test concepts are not really linked to any development tool/framework, at the end of the day the app must do what it's supposed to do gracefully.
Now, on the strategy topic, depends on a lot of variables, I will push just some to this answer, otherwise I will write an article here.
There is some stuff to think about, even before writing the strategy:
When we will test?
Local build and testing.
Remote build and testing (CI/CD stuff).
Pre merge testing (CI/CD stuff).
Pre production testing (CI/CD stuff).
Production monitoring tests (CI/CD stuff).
Do we have enough resources?
At least one person dedicated person for testing and it's tasks.
VMs/computers hosted by your company or cloud providers to run the tests in a CI/CD pipeline.
On my previous experiences with testing, when you are starting (low amount of coverage), end-to-end testing are the ones that did show more value, why?
It's mostly about the user perspective.
It will answer things like "Can the user even login on our app and perform a core task?" If you cannot answer this before a release, well you are in a fragile situation.
Covers how the application screens and feature behave together.
Covers how the application integrate with backend services.
Well, if it has issues with the API, it will most likely to be visible on the UI.
Covers if data is being persisted in a way that make sense to the user
It might be "wrong" on the database, but for who is using it still makes sense.
You don't need 500 hundred tests to have a nice coverage, but still this kind of test is costly to maintain.
The problem with the base (fast and less costly tests) of the pyramid when you have "nothing" is, you can have 50000 unit tests, but still not answer if the core works, why? For you to answer it you need to be exposed to a real, or near real world, unit doesn't provide it for you. You will be really limited to answer things like: "well in case the input is invalid it will show a fancy message. But can the user login?"
The base is still important and the test pyramid is still a really good thing to use for guidance, but my thoughts for you folks right now, as you are starting, try to get meaningful end-to-end cases, and make sure that they are working, that the core of the application, at every release, is there, working as expected, it's really good to release with confidence.
At some point the amount of end-to-end will increase, and you will start seeing the cost of maintaining it, so then you could start moving things down one step bellow in the pyramid, checks that were made on the e2e, now can be on the integration level, on the widget level, and etc.
Testing is a iterative and incremental work also, it will be changing as the team matures, trying to go strait to the near perfect world with it, will cause a lot of problematic releases, my overall point is, at first, try to have tests that gives meaningful answers.
Another note is: Starting in the top of the pyramid that is not supposed to be linked to any development framework (Flutter, react-native and etc) will also give you time to get up to speed into Flutter, while you are still contributing to e2e coverage, using things like Appium (SDETS/QA must have some familiarity with it) for example, could be a parallel work.
We have a fairly large system (~1m lines) which is heavily reliant on Entity Framework 6. This means our DbContext is passed around and used everywhere.
We also have lots of "unit" tests, that are using an actual SQL Server database. Each machine that runs tests has a dedicated database which gets wiped and set up with needed data before running each test.
This is of course not ideal in terms of speed, maintainability, ease of use, etc.
My end goal is to make all of our unit tests (~5k tests) not use an actual database, but a mock of some sort. I know this process is not going to be easy but I also want it to be as less painful as possible.
How can I make my tests faster and more unit scoped?
There is only one option here, and that is to make an in memory system. The unfortunate part of in memory is that it does not merge well with entity framework, like at all.
All of the mocks for Entity Framework are suggested as being done with mock databases, which you already have setup.
So the good news is that you can do it in memory on your own! The bad news is that you can do it, in memory, on your own.
You are going to have to create a mirror implementation of Entity Framework which works only on an in memory set of information. In many ways this is similar to event driven in memory cache systems and the benefit you will get out of creating a custom implementation for mocking in memory would be that you can easily port it over to support caching your database information and also allowing an interface for querying that information.
This will expose features such as event driven push technologies (SignalR) for live data. It will also take a lot of time. If the development time required to implement an in memory mock of entity framework is less than the time lost due to waiting for tests to complete in the mock database then it may be worth it.
We also have lots of "unit" tests, that are using an actual SQL Server database. Each machine that runs tests has a dedicated database which gets wiped and set up with needed data before running each test.
This is of course not ideal in terms of speed, maintainability, ease of use, etc.
My end goal is to make all of our unit tests (~5k tests) not use an actual database, but a mock of some sort. I know this process is not going to be easy but I also want it to be as less painful as possible.
I disagree with your conclusion. I recommend you keep the existing dedicated testing database, I actually think it's an excellent idea to test with an actual database because it will reveal any data-layer issues, such as if someone makes a change to the database schema without it being reflected in your EF Entity classes. The EF itself is fairly well tested so having code-coverage of EF-generated classes is a fool's errand in my personal opinion, and the disconnect between entity-classes and the database is probably the #1 area where things can (and will) go wrong.
I understand your performance concerns with using this approach, certainly there are potential optimizations to be had, such as not resetting the database before running every test (perhaps have the tests assume the database is in a known "good state" before starting) and only reset it after the test suite is completed.
I am working on JPA project and I want to have unit tests (although as a database is required, in this case it will be more as integration tests.)
What is the best way to test JPA project? jUnit can do that ? Is there other better way ?
Thank you very much
You have given limited information on the tools/frameworks you are using and a very general question, but I will give a quick answer on the points you raise. These are just pointers however as I believe you need to do a good bit more leg-work in order for you to figure out what is best for your particular project.
Junit allows you to target your class methods with specific parameters and to examine the return values. The returned values maybe an entity that should have certain field at certain values, a list of entities with certain expected field values, exceptions etc., etc. (Whatever you methods are). You can run your test as you introduce new functionality, and re-run them to test for regression as development proceeds. You can easily test edge cases and non-nominal stuff. Getting Junit up and running in Java SE/EE is quite straight forward so that could be a good option for you to get stick-in with testing. It is one of the quicker ways I use to test new functionality.
Spring/MVC – Using an MVC framework can certainly be useful. I have used JSF/Primefaces. But that is principally because the application was to be a JSF application and such development tests gave confidence that the ‘Model’ layer provided what was needed to the rest of the framework. So this provides some confidence in the model/JPA/DB layers (it is certainly nice to see the data that is delivered) but does not provide for flexible, nimble and targeted testing you might expect from Junit.
I think Dbunit might be something to look at when you’ve made some progress with JUnit.
See http://dbunit.sourceforge.net/
DbUnit is a JUnit extension (also usable with Ant) targeted at
database-driven projects that, among other things, puts your database
into a known state between test runs. This is an excellent way to
avoid the myriad of problems that can occur when one test case
corrupts the database and causes subsequent tests to fail or
exacerbate the damage.
This is regarding an issue I have been facing for sometime. Though I have found a solution, I really would like to get some opinion about the approach taken.
We have an application which receives messages from a host, does some processing and then pass that message on to an external system. This application is developed in Java and has to run on Linux/Oracle and HP-NonS top Tandem/SQLMX OS/DB combination.
I have developed a test automation framework which is written in Perl.This script traverses directories (specified as an argument to this script) and executes test cases specified under those directories. Test cases could be organized into directories as per functionality. This approach was taken to ensure that a specific functionality can also checked in addition to entire regression suite.For verification of the test results, script read test case specific input files which has sql queries mentioned in them.
In Linux/Oracle, Perl DBD/DBI interface is used to query Oracle database.
When this automation tool was run in Tandem, I came to know that there was no DBD/DBI interface for SQLMX. When we contacted HP, they informed us that it would be a while before they develop DBD/DBI interfaces for SQLMX DB.
To circumvent this issue, I developed a small Java application which accepts DB connection string, user name, password and various other parameters. This Java app is now responsible for test case verification functionality.
I must say it meets our current needs, but something tells me (do not know what) that approach taken is not a good one, though now I have the flexibility of running this automation with any DB which has a JDBC interface.
Can you please provide feedback on the above approach and suggest a better solution?
Thanks in advance
The question is a bit too broad to comment usefully on except for one part.
If the project is in Java, write the tests in Java. Writing the tests in a different language adds all sorts of complications.
You have to maintain another programming language and attendant libraries. They can have different caveats and bugs for the same actions, such as you ran into with a lack of a database driver in a certain environment.
Having the tests done in a different language than the project is developed in drives a wedge between testing and development. Developers will not feel responsible for participating in the testing process because they don't even know the language.
With the tests written in a different language, they cannot leverage any work which has already been done. They have to write all over again basic code to access and work with the data and services, doubling the work and doubling the bugs. If the project code changes APIs or data structures, the test code can easily fall out of sync requiring extra maintenance hassles.
Java already has well developed testing tools to do what you want. The whole structure of running specific tests vs the whole test suite is built into test suites like jUnit.
So I can underscore the point, I wrote Test::More and I'm recommending you not use it here.
Mock frameworks, e.g. EasyMock, make it easier to plugin dummy dependencies. Having said that, using them for ensuring how different methods on particular components are called (and in what order) seems bad to me. It exposes the behaviour to test class, which makes it harder to maintain production code. And I really don't see the benefit; mentally I feel like I've been chained to a heavy ball.
I much rather like to just test against interface, giving test data as input and asserting the result. Better yet, to use some testing tool that generates test data automatically for verifying given property. e.g. adding one element to a list, and removing it immediately yields the same list.
In our workplace, we use Hudson which gives testing coverage. Unfortunately it makes it easy to get blindly obsessed that everything is tested. I strongly feel that one shouldn't test everything if one wants to be productive also in maintenance mode. One good example would be controllers in web frameworks. As generally they should contain very little logic, testing with mock framework that controller calls such and such method in particular order is nonsensical in my honest opinion.
Dear SOers, what are your opinions on this?
I read 2 questions:
What is your opinion on testing that particular methods on components are called in a particular order?
I've fallen foul of this in the past. We use a lot more "stubbing" and a lot less "mocking" these days.
We try to write unit tests which test only one thing. When we do this it's normally possible to write a very simple test which stubs out
interactions with most other components. And we very rarely assert ordering. This helps to make the tests less brittle.
Tests which test only one thing are easier to understand and maintain.
Also, if you find yourself having to write lots of expectations for interactions with lots of components there could well be a problem in the code you're testing anyway. If it's difficult to maintain tests the code you're testing can often be refactored.
Should one be obsessed with test coverage?
When writing unit tests for a given class I'm pretty obsessed with test coverage. It makes it really easy to spot important bits of behaviour that I haven't tested. I can also make a judgement call about which bits I don't need to cover.
Overall unit test coverage stats? Not particularly interested so long as they're high.
100% unit test coverage for an entire system? Not interested at all.
I agree - I'm in favor of leaning heavily towards state verification rather than behavior verification (a loose interpretation of classical TDD while still using test doubles).
The book The Art of Unit Testing has plenty of good advice in these areas.
100% test coverage, GUI testing, testing getters/setters or other no-logic code, etc. seem unlikely to provide good ROI. TDD will provide high test coverage in any case. Test what might break.
It depends on how you model the domain(s) of your program.
If you model the domains in terms of data stored in data structures and methods that read data from one data structure and store derived data in another data structure (procedures or functions depending how procedural or functional your design is), then mock objects are not appropriate. So called "state-based" testing is what you want. The outcome you care about is that a procedure puts the right data in the right variables and what it calls to make that happen is just an implementation detail.
If you model the domains in terms of message-passing communication protocols by which objects collaborate, then the protocols are what you care about and what data the objects store to coordinate their behaviour in the protocols in which they play roles is just implementation detail. In that case, mock objects are the right tool for the job and state based testing ties the tests too closely to unimportant implementation details.
And in most object-oriented programs there is a mix of styles. Some code will be written purely functional, transforming immutable data structures. Other code will be coordinating the behaviour of objects that change their hidden, internal state over time.
As for high test coverage, it really doesn't tell you that much. Low test coverage shows you where you have inadequate testing, but high test coverage doesn't show you that the code is adequately tested. Tests can, for example, run through code paths and so increase the coverage stats but not actually make any assertions about what those code paths did. Also, what really matters is how different parts of the program behave in combination, which unit test coverage won't tell you. If you want to verify that your tests really are testing your system's behaviour adequately you could use a Mutation Testing tool. It's a slow process, so it's something you'd run in a nightly build rather than on every check-in.
I'd asked a similar question How Much Unit Testing is a Good Thing, which might help give an idea of the variety of levels of testing people feel are appropriate.
What is the probability that during your code's maintenance some junior employee will break the part of code that runs "controller calls such and such method in particular order"?
What is the cost to your organization if such a thing occurs - in production outage, debugging/fixing/re-testing/re-release, legal/financial risk, reputation risk, etc...?
Now, multiply #1 and #2 and check whether your reluctance to achieve a reasonable amount of test coverage is worth the risk.
Sometimes, it will not be (this is why in testing there's a concept of a point of diminishing returns).
E.g. if you maintain a web app that is not production critical and has 100 users who have a workaround if the app is broken (and/or can do easy and immediate rollback), then spending 3 months doing full testing coverage of that app is probably non-sensical.
If you work on an app where a minor bug can have multi-million-dollar or worse consequences (think space shuttle software, or guidance system for a cruise missile), then the thorough testing with complete coverage becomes a lot more sensical.
Also, i'm not sure if i'm reading too much into your question but you seem to be implying that having mocking-enabled unit testing somehow excluds application/integration functional testing. If that is the case, you are right to object to such a notion - the two testing approaches must co-exist.