Testing pyramid software

I often hear opponents of unit testing or TDD arguing that writing unit tests becomes pointless work where you have to test all your methods in order to come up with a high test coverage. Yes, you should test the public interface. More importantly, however, you don't test trivial code. Don't worry, Kent Beck said it's ok. You won't gain anything from testing simple getters or setters or other trivial implementations e. Save the time, that's one more meeting you can attend, hooray!

There's a nice mnemonic to remember this structure: "Arrange, Act, Assert". Another one that you can use takes inspiration from BDD. It's the "given" , "when" , "then" triad, where given reflects the setup, when the method call and then the assertion part. This pattern can be applied to other, more high-level tests as well. In every case they ensure that your tests remain easy and consistent to read. On top of that tests written with this structure in mind tend to be shorter and more expressive.

Now that we know what to test and how to structure our unit tests we can finally see a real example. We're writing the unit tests using JUnit , the de-facto standard testing framework for Java. We use Mockito to replace the real PersonRepository class with a stub for our test. This stub allows us to define canned responses the stubbed method should return in this test. Stubbing makes our test more simple, predictable and allows us to easily setup test data.

Following the arrange, act, assert structure, we write two unit tests - a positive case and a case where the searched person cannot be found. The first, positive test case creates a new person object and tells the mocked repository to return this object when it's called with "Pan" as the value for the lastName parameter. The test then goes on to call the method that should be tested. Finally it asserts that the response is equal to the expected response.

The second test works similarly but tests the scenario where the tested method does not find a person for the given parameter. All non-trivial applications will integrate with some other parts databases, filesystems, network calls to other applications. When writing unit tests these are usually the parts you leave out in order to come up with better isolation and faster tests. Still, your application will interact with other parts and this needs to be tested.

Integration Tests are there to help. They test the integration of your application with all the parts that live outside of your application. For your automated tests this means you don't just need to run your own application but also the component you're integrating with.

If you're testing the integration with a database you need to run a database when running your tests. For testing that you can read files from a disk you need to save a file to your disk and load it in your integration test. I mentioned before that "unit tests" is a vague term, this is even more true for "integration tests". For some people integration testing means to test through the entire stack of your application connected to other applications within your system. I like to treat integration testing more narrowly and test one integration point at a time by replacing separate services and databases with test doubles.

Together with contract testing and running contract tests against test doubles as well as the real implementations you can come up with integration tests that are faster, more independent and usually easier to reason about. Narrow integration tests live at the boundary of your service.

Conceptually they're always about triggering an action that leads to integrating with the outside part filesystem, database, separate service. A database integration test would look like this:. Figure 6: A database integration test integrates your code with a real database. Figure 7: This kind of integration test checks that your application can communicate with a separate service correctly. Your integration tests - like unit tests - can be fairly whitebox. Some frameworks allow you to start your application while still being able to mock some other parts of your application so that you can check that the correct interactions have happened.

Write integration tests for all pieces of code where you either serialize or deserialize data. This happens more often than you might think.

Think about:. Writing integration tests around these boundaries ensures that writing data to and reading data from these external collaborators works fine. When writing narrow integration tests you should aim to run your external dependencies locally: spin up a local MySQL database, test against a local ext4 filesystem. If you're integrating with a separate service either run an instance of that service locally or build and run a fake version that mimics the behaviour of the real service.

If there's no way to run a third-party service locally you should opt for running a dedicated test instance and point at this test instance when running your integration tests.

Avoid integrating with the real production system in your automated tests. Blasting thousands of test requests against a production system is a surefire way to get people angry because you're cluttering their logs in the best case or even DoS 'ing their service in the worst case. Integrating with a service over the network is a typical characteristic of a broad integration test and makes your tests slower and usually harder to write.

With regards to the test pyramid, integration tests are on a higher level than your unit tests. Integrating slow parts like filesystems and databases tends to be much slower than running unit tests with these parts stubbed out.

They can also be harder to write than small and isolated unit tests, after all you have to take care of spinning up an external part as part of your tests. Still, they have the advantage of giving you the confidence that your application can correctly work with all the external parts it needs to talk to. Unit tests can't help you with that.

The PersonRepository is the only repository class in the codebase. It relies on Spring Data and has no actual implementation. It just extends the CrudRepository interface and provides a single method header.

The rest is Spring magic. Our custom method definition findByLastName extends this basic functionality and gives us a way to fetch Person s by their last name. Spring Data analyses the return type of the method and its method name and checks the method name against a naming convention to figure out what it should do. Although Spring Data does the heavy lifting of implementing database repositories I still wrote a database integration test.

You might argue that this is testing the framework and something that I should avoid as it's not our code that we're testing. Still, I believe having at least one integration test here is crucial. First it tests that our custom findByLastName method actually behaves as expected. Secondly it proves that our repository used Spring's wiring correctly and can connect to the database. To make it easier for you to run the tests on your machine without having to install a PostgreSQL database our test connects to an in-memory H2 database.

I've defined H2 as a test dependency in the build. The application. This tells Spring Data to use an in-memory database. As it finds H2 on the classpath it simply uses H2 when running our tests.

When running the real application with the int profile e. I know, that's an awful lot of Spring specifics to know and understand. To get there, you'll have to sift through a lot of documentation. The resulting code is easy on the eye but hard to understand if you don't know the fine details of Spring. On top of that going with an in-memory database is risky business. After all, our integration tests run against a different type of database than they would in production. Go ahead and decide for yourself if you prefer Spring magic and simple code over an explicit yet more verbose implementation.

Enough explanation already, here's a simple integration test that saves a Person to the database and finds it by its last name:. You can see that our integration test follows the same arrange, act, assert structure as the unit tests. Told you that this was a universal concept! Our microservice talks to darksky. Of course we want to ensure that our service sends requests and parses the responses correctly. We want to avoid hitting the real darksky servers when running automated tests.

Quota limits of our free plan are only part of the reason. The real reason is decoupling. Our tests should run independently of whatever the lovely people at darksky. Even when your machine can't access the darksky servers or the darksky servers are down for maintenance. We can avoid hitting the real darksky servers by running our own, fake darksky server while running our integration tests.

This might sound like a huge task. Thanks to tools like Wiremock it's easy peasy. Watch this:. To use Wiremock we instantiate a WireMockRule on a fixed port Using the DSL we can set up the Wiremock server, define the endpoints it should listen on and set canned responses it should respond with.

Next we call the method we want to test, the one that calls the third-party service and check if the result is parsed correctly.

It's important to understand how the test knows that it should call the fake Wiremock server instead of the real darksky API. The secret is in our application.

This is the properties file Spring loads when running tests. In this file we override configuration like API keys and URLs with values that are suitable for our testing purposes, e.

Note that the port defined here has to be the same we define when instantiating the WireMockRule in our test. This way we tell our WeatherClient to read the weatherUrl parameter's value from the weather. Writing narrow integration tests for a separate service is quite easy with tools like Wiremock.

Unfortunately there's a downside to this approach: How can we ensure that the fake server we set up behaves like the real server? With the current implementation, the separate service could change its API and our tests would still pass. Right now we're merely testing that our WeatherClient can parse the responses that the fake server sends.

That's a start but it's very brittle. Using end-to-end tests and running the tests against a test instance of the real service instead of using a fake service would solve this problem but would make us reliant on the availability of the test service.

Fortunately, there's a better solution to this dilemma: Running contract tests against the fake and the real server ensures that the fake we use in our integration tests is a faithful test double. Let's see how this works next. More modern software development organisations have found ways of scaling their development efforts by spreading the development of a system across different teams. Individual teams build individual, loosely coupled services without stepping on each others toes and integrate these services into a big, cohesive system.

The more recent buzz around microservices focuses on exactly that. Splitting your system into many small services often means that these services need to communicate with each other via certain hopefully well-defined, sometimes accidentally grown interfaces. Interfaces between different applications can come in different shapes and technologies.

Common ones are. For each interface there are two parties involved: the provider and the consumer. The provider serves data to consumers. The consumer processes data obtained from a provider. In an asynchronous, event-driven world, a provider often rather called publisher publishes data to a queue; a consumer often called subscriber subscribes to these queues and reads and processes data. Figure 8: Each interface has a providing or publishing and a consuming or subscribing party.

The specification of an interface can be considered a contract. As you often spread the consuming and providing services across different teams you find yourself in the situation where you have to clearly specify the interface between these services the so called contract. Traditionally companies have approached this problem in the following way:.

More modern software development teams have replaced steps 5. They serve as a good regression test suite and make sure that deviations from the contract will be noticed early. In a more agile organisation you should take the more efficient and less wasteful route. You build your applications within the same organisation.

It really shouldn't be too hard to talk to the developers of the other services directly instead of throwing overly detailed documentation over the fence. After all they're your co-workers and not a third-party vendor that you could only talk to via customer support or legally bulletproof contracts. Using CDC, consumers of an interface write tests that check the interface for all data they need from that interface.

The consuming team then publishes these tests so that the publishing team can fetch and execute these tests easily. Once all tests pass they know they have implemented everything the consuming team needs. Figure 9: Contract tests ensure that the provider and all consumers of an interface stick to the defined interface contract. With CDC tests consumers of an interface publish their requirements in the form of automated tests; the providers fetch and execute these tests continuously.

This approach allows the providing team to implement only what's really necessary keeping things simple, YAGNI and all that. The team providing the interface should fetch and run these CDC tests continuously in their build pipeline to spot any breaking changes immediately. If they break the interface their CDC tests will fail, preventing breaking changes to go live. As long as the tests stay green the team can make any changes they like without having to worry about other teams. The Consumer-Driven Contract approach would leave you with a process looking like this:.

If your organisation adopts a microservices approach, having CDC tests is a big step towards establishing autonomous teams. CDC tests are an automated way to foster team communication. They ensure that interfaces between teams are working at any time.

Failing CDC tests are a good indicator that you should walk over to the affected team, have a chat about any upcoming API changes and figure out how you want to move forward. A naive implementation of CDC tests can be as simple as firing requests against an API and assert that the responses contain everything you need. You then package these tests as an executable. Over the last couple of years the CDC approach has become more and more popular and several tools been build to make writing and exchanging them easier.

Pact is probably the most prominent one these days. It has a sophisticated approach of writing tests for the consumer and the provider side, gives you stubs for separate services out of the box and allows you to exchange CDC tests with other teams. Pact has been ported to a lot of platforms and can be used with JVM languages, Ruby,.

NET, JavaScript and many more. If you want to get started with CDCs and don't know how, Pact can be a sane choice. The documentation can be overwhelming at first. Be patient and work through it. It helps to get a firm understanding for CDCs which in turn makes it easier for you to advocate for the use of CDCs when working with other teams. Consumer-Driven Contract tests can be a real game changer to establish autonomous teams that can move fast and with confidence.

Do yourself a favor, read up on that concept and give it a try. A solid suite of CDC tests is invaluable for being able to move fast without breaking other services and cause a lot of frustration with other teams. Our microservice consumes the weather API. So it's our responsibility to write a consumer test that defines our expectations for the contract the API between our microservice and the weather service. Instead of using Wiremock for the server stub we use Pact this time.

In fact the consumer test works exactly as the integration test, we replace the real third-party server with a stub, define the expected response and check that our client can parse the response correctly. In this sense the WeatherClientConsumerTest is a narrow integration test itself.

This pact file describes our expectations for the contract in a special JSON format. This pact file can then be used to verify that our stub server behaves like the real server.

We can take the pact file and hand it to the team providing the interface. They take this pact file and write a provider test using the expectations defined in there. This way they test if their API fulfils all our expectations.

You see that this is where the consumer-driven part of CDC comes from. The consumer drives the implementation of the interface by describing their expectations. The provider has to make sure that they fulfil all expectations and they're done. Getting the pact file to the providing team can happen in multiple ways.

A simple one is to check them into version control and tell the provider team to always fetch the latest version of the pact file. A more advances one is to use an artifact repository, a service like Amazon's S3 or the pact broker.

Start simple and grow as you need. In your real-world application you don't need both, an integration test and a consumer test for a client class.

The sample codebase contains both to show you how to use either one. If you want to write CDC tests using pact I recommend sticking to the latter. The effort of writing the tests is the same. Using pact has the benefit that you automatically get a pact file with the expectations to the contract that other teams can use to easily implement their provider tests. Of course this only makes sense if you can convince the other team to use pact as well.

If this doesn't work, using the integration test and Wiremock combination is a decent plan b. The provider test has to be implemented by the people providing the weather API.

We're consuming a public API provided by darksky. In theory the darksky team would implement the provider test on their end to check that they're not breaking the contract between their application and our service. Obviously they don't care about our meager sample application and won't implement a CDC test for us.

That's the big difference between a public-facing API and an organisation adopting microservices. The point of integration testing is to expose any issues or vulnerabilities in the software between integrated modules or components.

You would perform a unit test of the individual features first, followed with the integration test for each of the functions that are related. At the top of the pyramid is end-to-end E2E testing. This includes network connectivity, database access, and external dependencies. You can determine the success of an E2E test using several metrics, including a Status of Test to be tracked with a visual, such as a graph , and a Status and Report which must display the execution status and any vulnerabilities or defects discovered.

Within the levels of the testing pyramid are a wide variety of specific processes for testing various application functions and features, as well as application integrity and security.

One of the most important types of testing for applications is application security testing. Security testing helps you identify application vulnerabilities that could be exploited by hackers and correct them before you release your product or app. There are a range of application security tests available to you with different tests that are applicable at different parts of the software development life cycle.

You can find different types of application security testing at different levels of the testing pyramid. Each test has its own strengths and weaknesses. You should use the different types of testing together to ensure their overall integrity.

This is an example of unit testing. SAST analyzes the code itself rather than the final application, and you can run it without actually executing the code. According to the security analysts at Cloud Defense ,. You should apply SAST in the development phase of your software projects.

A good approach for you will be to design and write your applications to include SAST scans into your development workflow. On the other end of the spectrum is dynamic application security testing DAST , which tests the fully compiled application. You design and run these tests without any knowledge of the underlying structures or code. DAST operates by attacking the running code and seeking to exploit potential vulnerabilities.

While slow a complete DAST test of a complete application can take five to seven days on average , it will reveal to you the most likely vulnerabilities in your applications that hackers would exploit. IAST conducts continuous real-time scanning of an application for errors and vulnerabilities using an inserted monitoring agent. Compatibility testing assesses how your application operates and how secure it is on various devices and environments, including mobile devices and on different operating systems.

Compatibility testing can also assess whether a current version of software is compatible with other software versions. Version testing can be backward or forward facing. Modified versions of the testing pyramid can include a level that's next to or above end-to-end testing. This level consists of tests focused on the application user.

It is mandatory to procure user consent prior to running these cookies on your website. By Testim , November 25, Share on. This would require the following steps: Find the username text field and type the username. Locate the password text field and type the password. Click the submit button. The test automation pyramid is a framework that defines various types of tests and the number of times they should appear. Unit tests form the base of the test pyramid.

They should be frequent, and they should run fast. Integration tests are the middle tier of the pyramid. These tests focus on interactions of your code with the outside world, such as databases and external services. End-to-end tests top the test pyramid. More stories we think you will like. Product January 12, Announcements January 11, Mocking in Testing: from zero to hero In end-to-end E2E automated testing, we attempt to simulate how the end-user would use the product—clicking on buttons, filling out….

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