I'm currently working on a project where I'm using Jest for unit testing and code coverage.
Everything is working fine, except coverage for mocked classes/methods. I don't seem to get the desired coverage results. I've tried to find something in the Jest docs and searched online for an answer, but I can't seem to find anything about it.
The thing is that when I use a mocked implementation (for example ./services/__mocks__/UserService.js), the actual implementation (./services/UserService.js) results in having 0% coverage. This is a logical outcome, since the implementation is overwritten by the mock.
I can get around this by using /* istanbul ignore next */ on every method in the actual service or simply add the actual services to the coveragePathIgnorePatterns property in the Jest setup file and let it generate coverage for all mocked classes instead, but I wonder if there is any way to have Jest use the mocked implementation automatically for generating coverage results.
What is the way to go for mocked classes/functions and code coverage?
Thanks in advance!
As in documentation says for manual mocks, you'll use ./services/__mocks__/UserService.js only if you explicitly called something like jest.mock('./services/UserService');.
If you want to write tests for ./services/UserService, be convinced you don't use jest.mock('./services/UserService'); before this tests.
Related
I know that PIT Mutation Test framework can export mutation coverage information based on the test suite or the test class. However, I was wondering if there is an option to extract or export mutation coverage information based on the test case methods (test cases under the #Test annotation), so that I can see which test cases are written well and which are not. If it is not possible, the simplest solution that comes to my mind is commenting all the test methods and uncommenting only one of the test methods, run it and export the information. I wanted to know if there is an elegant solution.
Note: I know that MuJava provides such information.
This can be done with the (badly/un)documented matrix feature.
Assuming you're using maven you'll need to add
<fullMutationMatrix>true</fullMutationMatrix>
<outputFormats>
<param>XML</param>
</outputFormats>
To your pom.
The XML output will then contain pipe separated test names in the killing test nodes.
<killingTests>foo|foo2</killingTests>
<succeedingTests>bar</succeedingTests>
I am working with Golang and using mockhiato to generate mocks for all interfaces. This tool generates mocked implementation in mocks.go file within the same package. I can't rename mocks.go to mocks_test.go as this mock file is consumed by other packages.
The problem is that these mocks files are counted by go coverage tool and thus reducing my code coverage percentage for the package.
I am looking a good workaround so that my code coverage will not show bad numbers.
The best thing in this case would be to move the mocks to their own dedicated package which would have no test coverage. This would remove their impact on code that you actually want coverage data on.
That's how we solved it.
Put interface in the consumer folders. If service is injected in the handler, then the handler will have the interface definition of service. This is because GoLang philosophy suggests that interface is to consume functionality rather than expose it.
Used mockery to generate mocks.
Generate mocks in a separate _mock folder.
I came across Google Truth https://google.github.io/truth/ and thought to try it out. I read the information on that site but still have a basic question.
Is Truth a substitute for JUnit? How should I write the #test methods and test suites the way I write in JUnit and automate the test execution say through Jenkins? Or is it that Truth is just about making your assertion code beautiful and everything else stays the same?
Does Truth still needs help of JUnit framework (or something like JUnit)?
Thanks!
No, Google Truth isn't a full replacement for JUnit/TestNG. Truth is an assertion framework which allows you to write assertions more flexibly (see their Comparison page for details).
Truth however doesn't have a concept of tests/test suites/test runs/... so you'll still need a testing framework (like JUnit or TestNG) to actually execute your tests.
Let's assume we are not doing TDD (for which unit tests are obviously part and parcel), and have integration tests for all the use cases.
The integration tests assume assume a certain input and validate the output is as expected.
My thinking is that adding a unit test for a method that is traversed in an integration test, using the same data as would exist in the method in the integration test, would not expose any additional bugs.
That would lead to the conclusion that provided you have suffcient integration tests you do not then need to unit test the same code.
So, can someone give a concrete example where a unit test could expose a bug in the above scenario?
Integration tests can be seen as a form of Acceptance Testing. They ensure that the software is doing what it is supposed to be doing.
Unit tests, on the other hand, aren't particularly useful for customers. A customer is not concerned that the InitializeServerConnection is failing, but they are concerned that they're unable to send internal messages to their co-workers as a result.
So what good are unit tests for? They are a development tool, full stop. A unit test verifies that a cog in the machine is working properly. And if it is not, it is very easy to see it failing.
Arialdo Martini offers a great explanation:
Oversimplifying, a software system can be seen as a network of cooperating modules. Since they cooperate, some of them depend on other.
[...]
With integration and end-to-end tests you would be able to find all the broken features.
Yet, this is not of any help in guessing where the bug is. The same system, with the same bug, would result in these unit test failures:
So, even though a unit test doesn't add any business value, it does add value in the form of reducing the amount of time spent manually testing, debugging, and sifting through code looking for the root cause of an issue.
Consider something like this:
class UsersTable
{
public function findUserById($id)
{
$sql = "...";
return $this->adapter->execute($sql);
}
}
The entire class is pretty much nothing but methods that wrap SQL statements, and there is really no complex logic. I'd essentially be testing the SQL itself.
I know that tests that hit the database are often integration tests, but is this still an integration test since it's being tested so directly, as a unit test would be?
I would say that because your testing more than just the logic of that specific unit (findUserById), that it's an integration test. If you want to properly unit test, I would look into mock objects and dependency injection. Since it looks like you're using PHP, I'll guess you're probably using phpUnit to unit test, and phpUnit allows mocking. To unit test this function, you would want to mock the execute method of the adapter member and assert that it was called once with the correct $sql string. For these purposes, I would say you should assume that the execute method is working correctly, so there's no need to test it. Here is a link to phpUnit's which describes their object mocking.
I find that these integration tests are very useful, and compliment your pure unit tests in a nice way. They give you a good indication that your db is wired up correctly and compatible with your object model.
When I include these types of test I don't tend to mock the db since I can just as easily do all the testing in the integration test.
I do however recommend adding the data your are testing against as a precondition to the test.
I essentially follow this pattern:
1)Add user to DataBase
2)Call your method under test here
3)Assert that your retrieved user is the same as the one just created.
With this pattern you don't have to rely on existing data in the db that might change over time and make your tests fragile.