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# Introduction to Chi Square Distribution Test of a Single Variance

This statistics video tutorial provides a basic introduction of the chi square distribution test of a single variance or standard deviation.  It explains how to use it in order to determine whether or not you reject the null hypothesis.

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## The Ultimate Guide to Multiclass A/B Testing

One essential skill that certainly useful for any data analytics professional to comprehend is the ability to perform an A/B testing and gather conclusions accordingly.

Before we proceed further, it might be useful to have a quick refresher on the definition of A/B testing in the first place. As the name suggests, we can think of A/B testing as the act of testing two alternatives, A and B, and use the test result to choose which alternative is superior to the other. For convenience, let’s call this type of A/B testing as the binary A/B testing.

Despite its name, A/B testing in fact can be made more general, i.e. to include more than two alternatives/classes to be tested. To name a few, analyzing click-through rate (CTR) from a multisegment digital campaign and redemption rate of various tiers of promos are two nice examples of such multiclass A/B testing.

The difference in the number of classes involved between binary and multiclass A / B testing also results in a slight difference in the statistical methods used to draw conclusions from them. While in binary testings one would straightforwardly use a simple t-test, it turns out that an additional (preliminary) step is needed for their multiclass counterparts.

In this post, I will give one possible strategy to deal with (gather conclusions from) multiclass A/B testings. I will demonstrate the step-by-step process through a concrete example so you can follow along. Are you ready?

#hypothesis-testing #a-b-testing #click-through-rate #t-test #chi-square-test #testing

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## Testing Microservices Applications

The shift towards microservices and modular applications makes testing more important and more challenging at the same time. You have to make sure that the microservices running in containers perform well and as intended, but you can no longer rely on conventional testing strategies to get the job done.

This is where new testing approaches are needed. Testing your microservices applications require the right approach, a suitable set of tools, and immense attention to details. This article will guide you through the process of testing your microservices and talk about the challenges you will have to overcome along the way. Let’s get started, shall we?

## A Brave New World

Traditionally, testing a monolith application meant configuring a test environment and setting up all of the application components in a way that matched the production environment. It took time to set up the testing environment, and there were a lot of complexities around the process.

Testing also requires the application to run in full. It is not possible to test monolith apps on a per-component basis, mainly because there is usually a base code that ties everything together, and the app is designed to run as a complete app to work properly.

Microservices running in containers offer one particular advantage: universal compatibility. You don’t have to match the testing environment with the deployment architecture exactly, and you can get away with testing individual components rather than the full app in some situations.

Of course, you will have to embrace the new cloud-native approach across the pipeline. Rather than creating critical dependencies between microservices, you need to treat each one as a semi-independent module.

The only monolith or centralized portion of the application is the database, but this too is an easy challenge to overcome. As long as you have a persistent database running on your test environment, you can perform tests at any time.

Keep in mind that there are additional things to focus on when testing microservices.

• Microservices rely on network communications to talk to each other, so network reliability and requirements must be part of the testing.
• Automation and infrastructure elements are now added as codes, and you have to make sure that they also run properly when microservices are pushed through the pipeline
• While containerization is universal, you still have to pay attention to specific dependencies and create a testing strategy that allows for those dependencies to be included

Test containers are the method of choice for many developers. Unlike monolith apps, which lets you use stubs and mocks for testing, microservices need to be tested in test containers. Many CI/CD pipelines actually integrate production microservices as part of the testing process.

## Contract Testing as an Approach

As mentioned before, there are many ways to test microservices effectively, but the one approach that developers now use reliably is contract testing. Loosely coupled microservices can be tested in an effective and efficient way using contract testing, mainly because this testing approach focuses on contracts; in other words, it focuses on how components or microservices communicate with each other.

Syntax and semantics construct how components communicate with each other. By defining syntax and semantics in a standardized way and testing microservices based on their ability to generate the right message formats and meet behavioral expectations, you can rest assured knowing that the microservices will behave as intended when deployed.

## Ways to Test Microservices

It is easy to fall into the trap of making testing microservices complicated, but there are ways to avoid this problem. Testing microservices doesn’t have to be complicated at all when you have the right strategy in place.

There are several ways to test microservices too, including:

• Unit testing: Which allows developers to test microservices in a granular way. It doesn’t limit testing to individual microservices, but rather allows developers to take a more granular approach such as testing individual features or runtimes.
• Integration testing: Which handles the testing of microservices in an interactive way. Microservices still need to work with each other when they are deployed, and integration testing is a key process in making sure that they do.
• End-to-end testing: Which⁠—as the name suggests⁠—tests microservices as a complete app. This type of testing enables the testing of features, UI, communications, and other components that construct the app.

What’s important to note is the fact that these testing approaches allow for asynchronous testing. After all, asynchronous development is what makes developing microservices very appealing in the first place. By allowing for asynchronous testing, you can also make sure that components or microservices can be updated independently to one another.

#blog #microservices #testing #caylent #contract testing #end-to-end testing #hoverfly #integration testing #microservices #microservices architecture #pact #testing #unit testing #vagrant #vcr

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## Software Testing 101: Regression Tests, Unit Tests, Integration Tests

If you write automated tests and deliver them to the customer, he can make sure the software is working properly. And, at the end of the day, he paid for it.

Ok. We can segregate or separate the tests according to some criteria. For example, “white box” tests are used to measure the internal quality of the software, in addition to the expected results. They are very useful to know the percentage of lines of code executed, the cyclomatic complexity and several other software metrics. Unit tests are white box tests.

#testing #software testing #regression tests #unit tests #integration tests

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## Agile Testing: An introduction

When we talk about Agile the first thing that pops into our mind is Agile development. But here we are going to see and learn about an introduction to Agile Testing that how testers work in Agile, the contrast between Agile Testing and development, and traditional vs. Agile approach.

#### What is Agile Testing?

• In the world of software development, there are two very common terminologies, Developers (programmers) and testers. When we hear programmer we think of a person whose main task is to write production code. And when you hear tester you think of a person whose main task in testing and quality assurance.
• In Agile no one has only one task to perform, here everyone works on it with one aim in the mind that is to deliver the quality their customers need. In a traditional approach, this would have been the primary concern of the tester or the QA of the team. But in Agile even the development team tries to deliver quality end product to the customer.
• Agile is an iterative development methodology, where requirements evolve through collaboration between the customer and self-organizing teams. Agile aligns development with customer needs. Several core practices used by agile teams relate to testing.
• Test-driven development (TDD) is used for the development of the services. Where the programmer writes the tiny piece of test which fails. Then tries to write the code around it to make the test pass. It is an approach that many teams follows as it is a smart technique to avoid any bugs.

#### ROLES AND ACTIVITIES ON AN AGILE TEAM

The roles are divided into mainly two teams:

• Customer team
• Developer team
##### Customer team
• The customer team comprises business experts, product owners, domain experts, product managers, business analysts, etc. The customer team writes the stories for the development to work on. They provide examples and logic behind the requirements. Their main task is to clear any doubts and give clarification with real world use cases or examples. They are available in each iteration for guiding the Dev and QA teams as well.
• In a customer team, the testers have a crucial role to play. They help the customers express their requirements as tests.
##### Developer team
• The developer team comprises of Developer team includes programmers,system administrators, architects, database administrators, technical writers,security specialists. Each person in the team can be responsible for multiple roles. A developer can also be helping out in testing related activities and a tester could be helping the developers in debugging a issue.
• Testers are in the developer team as well because testing is one of the core tasks in Agile. Both the testers and the developers help each other in achieving the best quality end product for the customer.

#### Interaction between Customer and Developer Teams

• The customer and developer teams work closely together with a common goal to deliver value to the organisation. Testers does not have the sole responsibility for the quality of the product under development. The developer also helps them achieve this by trying to maintain the quality from the first phase of the development.
• The customer team with developer team prioritise stories which are crucial and are to delivered in each sprint. It’s totally up to the customer that what they want the developer team to work on. They can even request changes in between the sprint and the developer can work on it. If it does not affect the current scope of the story too much. Even if it does they can pick it up in the next upcoming sprint.
• It is not totally in the hands of the customer team to dictate how much work they want the development team to work on. The developer picks up work according to there bandwidth, estimates it and then starts working on it.
• Testers have a foot in each world, understanding the customer viewpoint as well as the complexities of the technical implementation. The testers or the QA team acts as a bridge between the customer and the developers. They don’t just understands the customer requirements but also looks at it from a technical viewpoint. and tries to see if it is feasible or not from the developers point of view as well.

### **HOW IS AGILE TESTING DIFFERENT? **

• By now you must be wondering how is Agile testing different from the the other traditional approach? Let’s see how it is like to work on a traditional team vs. an Agile team.

• In traditional team or approach the testers are not involved with developers from the starting phases of the software. Testers are involved in the last phases of the development where they get very little time to test the services on which the developers works for months.
• Each release cycle is for around 6 months where all the tasks are to be completed and released to the customer. Testers are involved in release planning and requirements definition.But after that they are involved in the end with rushed testing phase and sometimes a delayed release as well.
• The quality is the sole responsibility of the QA team only. If any of the requirements were missing or any other issue was found the testers were responsible. They didn’t even have the control over if the developer has even tested there code or not.
• The testers have the power to stop or postpone the release of they find any major issues in the release or if it is not according to the requirements.
• 6 months seems like a very long time but is not as even after this time the end result is not according to the customers expectations. Things gets deviated from the path and the end result is not covering all the requirements.
• The testers create there test plans according to the API specs but if the end product is not according to the defined requirements then the whole test plan simply fails.

#agile #api testing #integration testing #quality assurance (qa) #scaled agile #scrum #testing #unit testing #agile teams #agile transformation #test automation

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## How to Do API Testing?

Nowadays API testing is an integral part of testing. There are a lot of tools like postman, insomnia, etc. There are many articles that ask what is API, What is API testing, but the problem is How to do API testing? What I need to validate.

Let’s consider you have an API endpoint example http://dzone.com/getuserDetails/{{username}} when you send the get request to that URL it returns the JSON response.

The response is in JSON format like below

JSON

``````{
"jobTitle": "string",
"userid": "string",
"phoneNumber": "string",
"email": "user@example.com",
"firstName": "string",
"lastName": "string",
"country": "string",
"region": "string",
"city": "string",
"department": "string",
"userType": 0
}
``````

In the JSON we can see there are properties and associated values.

Now, For example, if we need details of the user with the username ‘ganeshhegde’ we need to send a **GET **request to **http://dzone.com/getuserDetails/ganeshhegde **

Now there are two scenarios.

1. Valid Usecase: User is available in the database and it returns user details with status code 200

2. Invalid Usecase: User is Unavailable/Invalid user in this case it returns status with code 404 with not found message.

#tutorial #performance #api #test automation #api testing #testing and qa #application programming interface #testing as a service #testing tutorial #api test