Bottom line : One DataSourceName per test and you have full test isolation in no time. Lets rerun the whole package tests! With databases, actually testing against different databases is going to be pretty critical if you intend to support running in production against multiple database engines.
With abstraction and the use of interfaces, we can have modules decoupled to interchange between a mocked module for testing and another module used for production. The purpose of Tech School is to give everyone a chance to learn IT by giving free, high-quality tutorials and coding courses. We do a test run against a copy of the actual database before deployment, and the final test run against the actual database during deployment.
In the following sections there will be more Golang code, and we found meaningful to answer if Golang is an object-oriented programming (OOP) language and as the Golang team explains, the answer is yes and no, as you can see on their official web page: https://golang.org/doc/faq#Is_Go_an_object-oriented_language. With a mock DB, we can easily set up and test some edge cases, such as an unexpected error, or a connection lost, which would be impossible to achieve if we use a real DB. Alright, now the stub for our mock Store is built. Even if libraries reduce coding time and are versatile tools that allow us to mock or stub, they could add unnecessary and unused code that make the tests difficult to understand. Golang is an intelligent language such that it checks if the contracts are being followed in order to define if an interface is being implemented.
First, we need to install gomock. More than that, we can use the Return() function to tell gomock to return some specific values whenever the GetAccount() function is called. In this application, the database is a complex, real system, and it is external to the code, so it seems like a good candidate to mock. If youre using a bash shell then you should edit the .bash_profile or .bashrc file instead. 2022 Mark Phelps. We should defer calling Finish method of this controller. Basically, this will send our API request through the server router and record its response in the recorder. This http.NewRequest function will return a request object or an error. But is it good enough to test our API with just a mock DB? As the readme on their github repo, there are some workaround solutions: I had the same error as you and I did the second one successfully. So far it seems like the community has few distinct schools of thought: - In-memory "real" DB solutions - such as tidb-lite for MySQL (, - Container based functional/integration style testing. So here we call httptest.NewRecorder() to create a new ResponseRecorder. Once again, Im gonna duplicate the test data, change its name to "InternalError". This is very important because it will check to see if all methods that were expected to be called were called. unit tests, regression tests, integration tests, security tests, etc. // Code that validates students would go here. Hey while running the mockgen command to create mock file, i am getting below error, do you have any idea why is there this error, it says go mod file not found, but it is present there. Then inside the loop, we declare new tc variable to store the data of current test case. That would make Store interface to have all of its functions in addition to the TransferTx() function that weve added before: Next, we have to go back to the api/server.go file and remove this * from *db.Store type because it is no longer a struct pointer, but an interface instead: Note that although we have changed the Store type from struct to interface, our code will still work well, and we dont have to change anything in the main.go file because the db.NewStore() function is now also returning a Store interface with the actual implementation SQLStore that connects to the real SQL DB. We should also specify the destination of the generated output file.
So which approach should we use? Have you ever started writing an application in Go that reads and writes to a database only to later be confused about how to properly write tests for it? You do this manually first, by inserting, updating, deleting books and authors in your application, but as an experienced developer, you know that you really should write tests! Then add this export command to the top of the file: Press Esc to exit the insert mode, then :wq to save the file and quit vim. In this case, we should change the second parameter of the GetAccount function call to gomock.Any(). MockStore is the struct that implements all required functions of the Store interface. Now in the buildStubs function, instead of returning sql.ErrNoRows, I return sql.ErrConnDone, which basically is one possible error that the db/sql package can return when a query is run on a connection that has already been returned to the connection pool. To setup the tests for the storage layer, youll need to first create a real SQL database and also create the books and authors tables. Of course, you will also need an AuthorStore to manage the authors in your app. If you want to join me on my current amazing team at Voodoo, check out our job openings here. In this article, we will learn how to use Gomock to generate stubs for the DB interface, which helps us write API unit tests faster, cleaner, and easily achieve 100% coverage. missing go.sum entry for module providing package github.com/golang/mock/mockgen/model; to add: If youd like to see this type of testing in actual code that also supports several databases, check out my open-source feature flag solution Flipt as I use this pattern pretty extensively in the storage/sql package for my tests. We can also specify how many times this function should be called using the Times() function. Depends on your product's intended use. Now with this struct definition, lets add the first scenario for the happy case. Instead, we can just use the recording feature of the httptest package to record the response of the API request. For example, here we have the Store interface that defines a list of actions we can do with the real DB. So we use this matcher: gomock.Eq() and pass the account.ID to it. We call tc.buildStubs() function with the mock store before sending the request, and finally call tc.checkResponse() function at the end to verify the result. Things would be more complicated if this source file imports packages from other files, which is often the case when we work on a real project. Softwaretestinghelp.com. And thats it!
So all we need to do is to call its EXPECT() function to build a stub, which tells gomock that: this GetAccount() function should be called exactly 1 time with this input accountID, and return this account object as output. prog.go:14:2: no required module provides package github.com/acetorscode/learningbank/db/sqlc: go.mod file not found in current directory or any parent directory; see 'go help modules' note: We arent concerned about the API layer for this post but only about testing the service and storage layers. Now Im gonna show you what will happen if in the getAccount() handler function of api/account.go file we dont call the store.GetAccount function. It makes writing unit tests so easy and saves us tons of time implementing the mock interface. If it is about testing data persistence, rephrasing my earlier response, we do not test data persistence, not very thoroughly anyway, because it is auto-generated by a tool. An interface is a type or structure that defines the methods (with their signatures) that need to be implemented for any object to fulfill it. Have a look at our careers page and reach out to us if you would like to be a part of our team! We will use this tool to generate the mock db, so its important to make sure that it is executable from anywhere. We write each test as a self-contained unit, independent of the other tests. So lets write a separate function to generate a random account. And were done. How do you test your data access in go code? Then Im gonna move all of these statements into that function. We use a simple for loop to iterate through the list of test cases. The second argument should equal to the ID of the random account we created above. Yee, it passed! It contains the generated Querier interface with all functions to insert and query data from the database: And here you can see it declares a blank variable var _ Querier to make sure that the Queries struct must implement all functions of this Querier interface. Posted on Nov 14, 2020 prog.go:12:2: no required module provides package github.com/golang/mock/mockgen/model: go.mod file not found in current directory or any parent directory; see 'go help modules' When I first started it, I just wanted to save time from having to write repetitive mapper for each data type. How to create and verify JWT & PASETO token in Golang, Implement login user API that returns PASETO or JWT access token in Go, 's package is set to one of its inputs (usually the main one) and the output is stdio so mockgen cannot detect the final output package. It was tedious to write such tool, but it was a time well spent. After setting up the stub, we can simply use this mock store to test the API. // Specific and customized scan code goes here, using valuesInRow if you want. It will be a real implementation of the Store interface that talks to a SQL database, which is PostgreSQL in this case. The last scenario we should test is BadRequest, which means the client has sent some invalid parameters to this API. Lets jump into coding to see how it really works! Im gonna create a new file account_test.go inside the api package. prog.go:12:2: missing go.sum entry for module providing package github.com/golang/mock/mockgen/model; to add: It has 2 input arguments: a testing.T, and a httptest.ResponseRecorder object. We can use this mock store to build the stub that suits the purpose of each test case. To do this, well need a slight refactor of our Store code by abstracting away the implementation and instead relying on interfaces in the service layer. We can use it to start the test HTTP server and send GetAccount request. But their behavior could be important, so we define interfaces in our code to use custom implementations of the interfaces and use a custom implementation for our tests. Sqlite does support in-memory only database. Yes, database libraries export some methods and their implementation is not very important to us. It does not test anything. postgres createdb dropdb migrateup migratedown sqlc test server mock, // account, err := server.store.GetAccount(ctx, req.ID), // ctx.JSON(http.StatusNotFound, errorResponse(err)), // ctx.JSON(http.StatusInternalServerError, errorResponse(err)), Backend Master Class [Go + Postgres + Kubernetes + AWS]. Your tests are isolated, and compliant with go tools. So we dont need to run the source command every time we open the terminal. Then the old Store struct will be renamed to SQLStore. Understanding why tests must be isolated is important. So lets use the -destination option to tell it to write the mock store codes to db/mock/store.go file: Now get back to visual studio code, we can see that a new file store.go is generated inside the db/mock folder: In this file, there are 2 important struct: MockStore and MockStoreMockRecorder. All we have to do is to change this emit_interface setting in the sqlc.yaml file to true: Then run this command in the terminal to regenerate the codes: After this, in the db/sqlc folder, we can see a new file called querier.go. In the db_test.go file we can make use of Gos built-in testing package and the TestMain function. Dont worry if you dont fully understand it right now. Maybe there is something I don't understand. While you're here, sign up to receive a Thanks for reading! It makes our code more resilient, less prone to unintended consequences and gives us the confidence to deploy code iteratively. Its name is "OK". So lets build stub for this method by calling store.EXPECT().GetAccount().
Mock objects meet the interface requirements of, and stand in for, more complex real ones. And looking at the code of the getAccount handler, we can see that it is 100% covered. The reason is that Gin is running in Debug mode by default.
Im gonna use an anonymous class to store the test data. What you could end up with is obscure code that is not easily understood nor maintained. https://golang.org/doc/faq#Is_Go_an_object-oriented_language, https://www.softwaretestinghelp.com/types-of-software-testing/. If techschoolguru is not suspended, they can still re-publish their posts from their dashboard. Methods like validators that do something specific for the internal use of a library and we dont need to export them). File system full error with configurable maximum database size. Once unpublished, all posts by techschoolguru will become hidden and only accessible to themselves. Once suspended, techschoolguru will not be able to comment or publish posts until their suspension is removed. The actual implementation of this CRUD logic is outside of the scope of this post, but there are some excellent tutorials on how to use SQL in Go such as: A small snippet of this CRUD code may look something like this for inserting a book: Again, these details dont matter for the sake of this post, but what does matter is that we have a type BookStore that can perform actions on books such as inserting, reading, updating, and deleting them in the database.
Granted, we write more code by not using mocking libraries, but it shouldnt be an arduous task because our code should be modular, easy to understand and well decoupled. There are several mock packages that you can find. Then you create a type that implements this against your database backend, and another that you use for testing. [online] Available at: <. And the reason is due to a missing call to the store.GetAccount function. The content of this file will be very similar to that of the main_test.go file in the db package, so Im gonna copy this TestMain function, and paste it to our new file. Here Times(1) means we expect this function to be called exactly 1 time. On Tue, Jul 27, 2021 at 6:20 PM Levieux Michel <, On Tue, Jul 27, 2021 at 7:19 PM Markus Zimmermann <, On Wednesday, July 28, 2021 at 3:05:43 PM UTC+7. 2021/05/31 19:12:53 Loading input failed: exit status 1.
We gonna run each case as a separate sub-test of this unit test, so lets call t.Run() function, pass in the name of this test case, and a function that takes testing.T object as input. Built on Forem the open source software that powers DEV and other inclusive communities. This code is responsible for taking the models in Go code and converting the data to SQL and back again. Now go back to the test, we call randomAccount() function to create a new account. I'm using vim, so let's press i to enter the insert mode. For now, lets refactor the code a bit to make it work for multiple scenarios. It will have 3 input arguments: the testing.T, the response body of type byte.Buffer pointer, and the account object to compare. Next, for the buildStubs function, Im gonna copy its signature here. It is worth mentioning that sub-tests are solely related to their parents and they must be isolated from each other. After all, since mocks are in memory, it would satisfy requirements 2 and 4 above, as it would allow the tests to run quickly and keep the test data separate from production data in the database. Once you have good unit tests for your database-interacting low-level functions, and integration tests for the whole flow, you can just mock the db behavior in other higher level unit tests because you know it'll work in production.
So our goal is achieved! If you have that problem you have poorly written tests.
Copy this go get command and run it in the terminal to install the package: After this, a mockgen binary file will be available in the go/bin folder. Thanks a lot for reading and see you soon in the next lecture. Mocking complex systems like SQL databases is quite hard What I have seen many times is just to have a "seed-based" local database that is used in local integration tests. First, lets create the interfaces that will allow us to keep the database library code and implemented mocks separate. Similarly, we have a checkResponse function to check the output of the API. And since the account is not found, we can remove the requireBodyMatchAccount call. Lets comment out this block of code and just set account to be an empty object. Queries order matter! Next, Im gonna show you how to transform this test into a table-driven test set to cover all possible scenarios of the GetAccount API and to get 100% coverage. Lets open the browser and search for gomock. Which means that, having tests T1, T2 and T3, each one could be executed in isolation like a black box. Then we call json.Unmarshal to unmarshal the data to the gotAccount object. At the moment, in the api/server.go file, the NewServer() function is accepting a db.Store object: This db.Store is defined in the db/sqlc/store.go file. Now that we know that the code that interacts with the database can be well tested and uses actual SQL, we can start testing our service layer by introducing mocks when needed. Then open its Github page. Theyre just general interface type: Later we will see how this function is used to build stubs. Then everything will be working just fine when being put together. Writes package documentation comment (godoc) if true. Then lets delete all statements of this function, except for the last one. And thats it! The same is available in Object Oriented Programming (OOP) where we can expose the methods for a class (as public methods) and hide their implementation (e.g., We usually dont care about the implementation of a method of a library, we just use it) and also hide methods (as private methods) that are usually helper methods in a library (e.g. But it only covers the happy case for now. Then move the 2 require commands into it. Next we need to create a new mock store using this mockdb.NewMockStore() generated function. We will add more cases to this list later. For now, lets create a new store by calling mockdb.NewMockStore() with this input controller. Now lets go back to the unit test and call requireBodyMatchAccount function with the testing.T, the recorder.Body, and the generated account as input arguments. Now lets go back to our test file and run the whole package tests. Note that the input arguments of this Return() function should match with the return values of the GetAccount function as defined in the Querier interface. It produces different SQL for different databases. The manually typed SQL commands were also error prone, and not everybody in the team is familiar with various SQL dialects. Now, what if we want to check more than just the HTTP status code? The account ID should be account.ID. First we call ioutil.ReadAll() to read all data from the response body and store it in a data variable.
-source string It will return a db.Account object, where ID is a random integer between 1 and 1000, Owner is util.RandomOwner(), Balance is util.RandomMoney(), and Currency is util.RandomCurrency(). (source mode) Input Go source file; enables source mode. You might also want to look at podman, which runs containers directly as processes under your own userid with no docker daemon - and buildah, the corresponding tool for creating container images. It supports a limited number of databases. All passed.
You can apply this knowledge to write tests for other HTTP APIs in our simple bank project such as Create Account or Delete Account API. Now we just work with data models and not worry about testing the SQL instructions. Under what conditions?)? Occasionally, we use SQLite in-memory database to double-check certain functionality work as intended. Then we call server.router.ServeHTTP() function with the created recorder and request objects. Im gonna duplicate this Store struct definition and change its type to interface. In this section we present a code snippet to show how to use interfaces and mocks with the application of abstraction to test how our code interacts with external factors like a database. Interested in working with us? This application persists its data to a SQLite database. We switched from SQLite to PostgreSQL as our "in memory" database. We still have to test 2 more cases: InternalServerError and BadRequest. So I wrote the tool to auto generate the necessary code. Updates the environment with fixed arguments or updates needed according to the test case. The source mode will generate mock interfaces from a single source file. Well, I would say its up to you. In the account.go file, we can see that this getAccount handler is not 100% covered. Lucky for us, the sqlc package that we used to generate CRUD codes also has an option to emit an interface that contains all of the function of the Queries struct. It will become hidden in your post, but will still be visible via the comment's permalink. There are many duplicate debug logs written by Gin, which make it harder to read the test result. Thats because in the real implementation of the Store that connects to Postgres, the db/sql package will return this error if no account is found when executing the SELECT query. A working example would be: This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository. // Package mockdb is a generated GoMock package. But we need to change our buildStubs function a bit. Once unpublished, this post will become invisible to the public -write_package_comment DEV Community 2016 - 2022. In-memory SQL engine in Go sql/driver for testing purpose. To achieve the isolation in unit testing we can apply abstraction. We can use the same accountID here because mock store is separated for each test case.
[1]), this post will focus on Unit Tests. Another, quite efficient solution is to have a test suite's database initialized once and used for all subsequent unit tests. You do not have permission to delete messages in this group, Either email addresses are anonymous for this group or you need the view member email addresses permission to view the original message, Back in 2014 Andrew Gerrand made nice talk . To model the business logic, the data models look something like this: Next, you write all the code required to do basic CRUD in the application. Other than that, they serve a similar purpose. mockgen -build_flags=--mod=mod -package mockdb -destination db/mock/store.go github.com/phihdn/simplebank/db/sqlc Store. This status code is recorded in the Code field of the recorder.
We require no errors to be returned. For the checkResponse, we must change the status code to http.StatusBadRequest. youll only end up unhappy. And thats all. Im gonna duplicate the happy case's test data. Hit me up on Twitter and let me know what you thought of this post or if you have any tips regarding testing. In the tests, we pass our mock objects and in the production code we pass the objects that the database library provides. If you use a real DB, all tests will read and write data to the same place, so it would be harder to avoid conflicts, especially in a big project with a large code base. Then we have a fake DB MemStore struct, which implements all actions of the Store interface, but only uses a map to read and write data.
They all have their quirks, and you need to test for those. All Rights Reserved, except for the parts enumerated below. OK, so today we have learned how to use gomock to generate mocks for our DB interface, and use it to write unit tests for the Get Account API to achieve 100% coverage.