API Testing Interview Questions with Simple Answers

API Testing - Interview Questions

Application Programming Interface or API is an interface that helps the user to communicate and smooth data exchange between two systems. It is a cluster of functions that can be easily executed by any other software program. Basically, API works on the principle that it takes the command or request from the sources system and transfers that to the database where it executes the command/request, fetches the required data, and then returns the response to the source as asked. Before jump into API Testing – Interview Questions, let’s see about API Testing and its types.

The best thing about API is it takes and gives the response from the user without revealing the user’s internal details, which describes it as an Abstraction of API. 

API Testing and Its Types

Testing an API means testing the reliability, functionality, performance, and security of that particular application. It is carried directly on API, and the prime reason to do so is to check the Software Architecture and its Business Logic Layer.

There are several types of testing when it comes to API testing. Some are as follows:

  • Functional Testing
  • Unit Testing
  • Security Testing
  • UI Testing
  • Load Testing 
  • Runtime/Error Detection
  • Penetration Testing

It’s quite important here to mention the tools used in API Testing as, without it, none of the above-mentioned processes and types of API Testing can be possible enough to carry out. Tools in API Testing are PostMan, Parasoft SOAtest, and ALtersite API Monitoring. Different tools hit different targets to access, which makes it easier to organize the errors and responses and makes the whole process time-efficient. 

Principles of API Test Design

We know something about API and its testing with the types of the same but understanding the basic principles on which API test Designs are constructed and carried through is crucial. So, the basic principles of API Test Design are:

  • Instead of Exhaustive testing  we need an optimal amount if testing solely asked on the assessment of the risk of that particular application.

  • DEFECT  CLUSTERING: It states that the most number of defects are found in the smaller number of  modules or to simplify the more we have modules the less defects are found and the less modules one program has comes with more number of defects. 

  • Techniques should be improved continually and thus test cases should be updated and revised which would in turn help the testers to find more and more defects.

  • The core of testing is to find the defects and thus it’s away from the notion of its absence in a specific software. Software testing makes a software less vulnerable and more suitable for the users and their needs.

  • The time of testing is as important as the software itself. A software should be kept under testing as early as possible which helps in refinement of the software in early phases. Moreover, it’s easy to locate the errors in early stages.

  • As no software is same, thus for different types of software there should be a different testing process which will meet different needs of the users and in turn find specific errors.

The principles mentioned holding the core of API testing, which are laid after considering every aspect. This is the only reason because the refinement of the program is at its max, an Error/Bug-free program, and meets the demands of the users.

Interview Questions on API Testing

Apart from the basics regarding API testing, we went through now, there is still a lot to explore and know about it, which can be potentially asked in interviews. We have to understand the importance of API testing, and thus it is more frequently asked in interviews worldwide. It is quite important when it comes to the software testing fields, rather nowadays, it is being included in every field, and it is the only reason for API testing-related questions being in trend.

NOTE: Questions regarding the definition of API and API testing, its types, and tools used in API are covered in the above paragraphs itself.

Below are the frequently asked questions on API Testing with answers:

  1. What are the protocols in API Testing?

Protocols that are being used in API testing are:

  • SOAP
  • HTTP
  • JMS
  • UDDI
  • REST
  1.  Explain what is API Framework and API test environment?

API Framework is the file that has the list of all APIs that are mandatory for the activation for a specific program run, and it is described with the help of config. API Test Environment is the software application that does a method the server and database structure, and it’s devoid of the Graphical User Interface (GUI).

  1. What are the Advantages of API Testing?

The advantages of API testing are as follows:

  • Time Effective: API testing consumes less time than any other testing such as GUI testing and requires less codes which provides faster results and better coverage of the code.
  • Testing of Core Functionality: In the API testing the core of any program is tested before its GUI which helps in detection of the issues that are minor and can turn out to be disastrous during the GUI tests.
  • API testing is independent of language which makes it easy for the users to opt any language when performing automation test device for that particular program.
  • Integration of GUI and API testing evolved as a beneficial option as it is helpful in performing some functional GUI tests.
  1.  What are the bugs that are found during the API testing?

Some of the common bugs that are found in API testing are:

  • Security Bugs
  • Redundant or Absent Functionality
  • Reliability
  • Stress
  • Performance
  • Multi-Thread Issues
  1. What the major hurdles faced while performing API testing?

Challenges faced while performing API testing are:

  • Sequencing of call.
  • Validation and verification of the output.
  • Selection of parameter.
  • Absence of GUI resulting in difficulty on the user’s end to give values.
  1.  What are the most common templates used in API documentation?

Templates make it simpler for API testing as every template pays to focus on a particular area that simplifies the complete process. Some of the frequently used templates are:

  • Miredot
  • API Blueprint
  • Swagger
  • RestDoc
  • FlatDoc
  • Slate
  • Swagger
  • Web Service API Specification
  1. Define SOAP API and REST API and state what are the differences between them?

SOAP stands for Simple Object Access Control. It is a protocol based on XML, which is helpful in the exchanging of information between the two systems. REST stands for Representational State Transfer, and it is helpful for the developers while performing requests when a response is incoming. To make contact with the REST API, HTTP protocol is required.

1.Simple Object Access ControlRepresentational State Transfer
2.SOAP is a kind of protocolIt represents an architectural pattern.
3.In SOAP, all the data and inputs are done in XMLIt supports different data formats like HTML, XML, JSON.
  1. What do you mean by API Documentation?

API documentation acts as an easy reference to access the library or while working in a program. Documentation refers to a blueprint of proper planning and layout of a program with a source of content and all the related information regarding each function. Documentations that helps in accessing all the parameters are:

  • Type and Syntax of message of error when arise.
  • Description of function.
  • Elements, Syntax and Sequence related to each parameter.
  • Links of Functions.
  1. What actually is targeted when we say that we need to verify in API testing?

Basically, API testing means to give a command or request for a specified data which is known and then have a proper analysis of the response generated. In API testing following things are observed and verified:

  • Status code of HTTP.
  • Authorization will be rectified.
  • Accuracy of the data.
  • Response time is observed.
  • Error codes when the number of errors are high in number.
  1. What are the key elements of an HTTP request?

An HTTP request/command consists of five key elements, which are:

  • URI: Also known as Uniform Resource Identifier, is the identifier of all the resource present on the server.
  • Request Header: It carries the metadata for the message of HTTP request. Metadata can be of client type, cache setting, format of body, format accessed by client etc.
  • Action indicating HTTP methods like GET, POST, DELETE and PUT.
  • Request body which shows the message content and representation of the resource.
  • It indicated the HTTP version for example HTTP V1.1.

Except for these above-mentioned questions, still, there is a lot to study and practice about such a vast topic. Still, these questions are the most asked question regarding API testing in interviews and cover the basic concepts regarding providing a clear enough picture for the basic knowledge of API and can easily crack interviews asking API as their question.

API Testing Interview Questions with Simple Answers

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