Here is a top-notch, expert-curated list of API interview questions and answers that will enable you to successfully ace API testing interview questions. These API testing interview questions and answers are a combination of API testing interview questions for experienced or advanced levels and API automation testing interview questions for beginner levels. You may confidently answer questions pertaining to employment roles such as automation tester, azure developer, API testing engineer, test engineer, software developer, and automation engineer by using the prepared questions of the beginner and advanced levels and the descriptive answers. Make a good impression at your next interview with companies like Cognizant, Accenture, Wipro, HCL, Infosys, and JPMorgan Chase by being well-prepared with these api testing interview questions and answers.
API stands for an application programming interface. It is a software interface. The main purpose of API is to connect two or more applications that share data with each other. It is responsible for improving the productivity of an organization and keeps the data of the application in sync. API testing is the process that validates API testing and verifies the application's usability, conduct, security, and efficiency. It guarantees that the created APIs live up to the expectations of the organization. An application programming interface (API) links computers or pieces of software to one another as opposed to a user interface, which connects a computer to a human. The only person (the end user) who is supposed to utilize it is a computer programmer who is integrating it into the software.
A programming language interface (API) frequently consists of various components that serve as tools or services for programmers. A program or programmer is said to invoke a particular section of the API when they use it. The calls that make up the API are sometimes referred to as endpoints, subroutines, methods, or requests. These calls are defined by an API specification, which means that it describes how to use or implement them. By abstracting the underlying functionality and just exposing the objects or actions the developer requires, an API makes programming simpler when creating apps. An API for file input/output could give the developer a function that copies a file from one location to another without necessitating that the developer understand the file system operations taking place behind the scenes, in contrast to a graphical interface for an email client that might give the user a button that completes all the steps for fetching and highlighting new emails.
Application programming interfaces (APIs) are tested both directly and as part of integration testing during API testing to see if they live up to expectations for functionality, dependability, performance, and security. API testing is carried out at the message layer because APIs are devoid of a GUI. Because APIs increasingly serve as the principal interface to application logic and because GUI tests are challenging to maintain given the short release cycles and rapid changes often employed with Agile software development and DevOps, API testing is now considered essential for automated testing.
APIs are tested to see if they respond correctly (in a particular intended format) to a wide range of realistic queries, respond appropriately to edge circumstances like failures and unexpected/extreme inputs, deliver results quickly enough, and protect against security threats. By mimicking APIs and services that are not available for testing, service virtualization is used in conjunction with API testing to isolate the services that are being tested as well as to increase access to the test environment.
Test API is a library that is a collection of test and utility APIs that enable engineers and developers to make testing tools and computerized tests. Test API is an essential tool for developers. An API testing approach should start with a precisely defined programme scope and a thorough comprehension of how the API is intended to function. To make sure the application programming interface is functioning properly, various API tests can be run. They span general to specialised software analysis. API testing ensures that platform connections that are provided by API are dependable, safe, and easily scalable. automation of GUI tests, which speeds up testing and lowers testing costs. By allowing developers to access the app without using the user interface (UI), API testing enables developers to find bugs earlier in the development process rather than waiting for them to escalate into larger problems. Additionally, this saves money because faults can be fixed more effectively when they are discovered early.
REST API stands for Representational State Transfer Application Programming Interface. It is a set of architectural constraints. This architectural style REST API is used extensively in web designing. Doing Web Designing and Development courses alongside REST API can be beneficial for any developer. REST API automation interview questions are very important from an interview point of view. Four interface limitations are specified by REST:
1) Resource identification
2) Mismanagement of resources
3) Self-descriptive messages
4) and hypermedia as the application state's driving force
In general, it describes a machine-to-machine interface, and more specifically, it permits the substitution or addition of server-side rendering in web development to help client-side rendering in client-server models, where the web browser serves as the client for web applications. Performance, scalability, simplicity, modifiability, visibility, portability, and dependability are all things that REST aims to improve. Following REST concepts, such as a client-server design, statelessness, cacheability, usage of a layered system, support for code-on-demand, and use of a standard interface, allows for this. To qualify as RESTful, a system must adhere to these standards.
The browsers we use today come with built-in APIs, known as browser APIs. They give programmers the ability to carry out complicated operations without having to manage the intricate lower-level code. Browser APIs are used by developers and designers extensively, for anyone who is involved particularly with browser APIs should enroll in various web development courses to gain knowledge, Java Full Stack Developer Training is a good course, to begin with. Browser APIs are APIs that offer native functionalities that may also be utilized in a web app and are integrated into the browser.
These are also referred to as web APIs. The fact that most of the Web APIs have not yet been standardized is a significant drawback of using a browser API. This means that a web API's support may vary from one web browser to the next. For instance, an API that is not currently supported by Firefox or Edge may function using the Chrome browser.
We can quickly implement some functionality with web APIs and fewer lines of code, like:
This is one of the trick api automation interview questions asked by interviewers to test the basic knowledge of beginners. API is an interface, not software, that enables data interchange and functioning between various software applications or processes. Although an API offers functionality and access to data, it may also be seen as software that meets our demands. One kind of API is the interface to a software library. The library is a "real implementation" of this set of guidelines, whereas the API specifies and explains the "anticipated behavior" (a specification).
A single API might be implemented in many libraries using the same programming interface, or it can be abstract and have no implementations at all. Programs developed in one language may be able to utilize libraries written in another due to the separation of the API from its implementation. For instance, Scala developers can utilize any Java API because Scala and Java compile to compatible bytecode.
The five principles of API testing are:-
There are many different types of API testing, which are:
There is a certain procedure followed for performing API, in addition to the standard SDLC process, API automation testing should at least include the following testing approaches:
One must keep the following things in mind while performing API testing. Here are a few things to think about to make sure you get the most out of your tests throughout the product's life cycle if you want to get into API testing to gain the long-term rewards with less of a short-term burden.
Whenever it comes to information, APIs may be powerful tools. An API endpoint can be created by a developer that returns a ton of useful data for use by another program. The developer may also give users control over the data that is returned. But just like with any software development, it's important to take extra precautions with APIs to make sure they're only creating the data that's required at the moment—neither more nor less.
Testing the graphical user interface is known as UI (User Interface) testing. UI testing is focused on how the program looks and feels, including how the user interacts with its components like graphics, typeface, layout, etc. UI testing is different from API testing. API testing makes communication possible between two software systems. API satisfies the requirements for functionality, dependability, performance, and security. It does backend operations and is familiar with backend testing. Unlike UI testing, API testing focuses on the operation of the business intelligence. The business logic layer of the software architecture is the main focus. The appearance and functionality of an application will not be a focus of this testing.
A bug is a mistake in software or hardware. While bugs are typically the product of programmer error or oversight, they can also enter a programme through compiler errors, false assumptions about how hardware or software interfaces work, or they can be purposefully incorporated into software to produce disguised interfaces or back doors. While vulnerabilities frequently result in software crashing or other unexpected effects, some bugs can be used to break into an otherwise protected computer system.There are many bugs we find in API testing, which are:-
HTTP methods are an important concept for REST API testing interview questions. The following are the HTTP methods supported by REST API.
A type of memory called a cache is used to speed up data access. Normally, the main memory contains all the data needed for any process. However, if it is utilized frequently enough, it gets momentarily moved to the cache memory. Caching is the technique of storing and retrieving data from a cache. Caching is an important concept in REST assured API testing interview questions. Caching helps networks run more efficiently by easing the burden on servers. It is the ability to keep copies of data that is accessed frequently. The POST HTTP mode has Post requests that can be made cacheable. However, Get requests of the GET HTTP mode are cacheable by default.
The act of damaging digital systems and networks by gaining unauthorized access to a computer system or account is a popular definition of hacking. Although hacking is not always harmful, it is most frequently linked to online crime and data loss by cyber criminals.
Hacking is the term for using technology improperly to harm or destroy systems, obtain user data, steal data and documents, or obstruct data-related activity. Examples of such technology include desktops, cellphones, tablets, and networks. The stereotypical image of a hacker is a lone, miscreant programmer with advanced coding and system modification skills. However, this limited perspective does not account for hacking's underlying technological nature.
Yes, it is possible. This is due to the fact that we are making requests via the internet, which mostly uses the HTTP protocol. This protocol is easy to read because it is text-based. Therefore, security testing of the APIs is necessary to create safer systems.
After the initial level of testing each individual API, security testing typically begins. You make test cases with faulty requests in addition to legitimate inputs. All the so negative tests enable you to assess the effectiveness of your API error handling. Through the clever design of incorrect inputs that could crash your API or expose data, you can also utilize these negative tests to confirm the security of your API. Discovering API utilization and potential edge situations that are worth testing can be accomplished by gaining insight from tracing data using a variety of methods. APIs can be hacked easily while testing an API so we test the security of an API. When evaluating the API, we must validate two elements in order to check its security:
API tools are widely available and help developers accomplish their tasks more quickly. They contain solutions for programming, testing, debugging, writing documentation, and other related tasks. The use of API testing tools enables effective API testing and monitoring. Any kind of API is supported by it. The design of complicated tests for API verification, managing, and analyzing API testing, etc. is made possible by the API Testing tools solution. API Testing indeed is a difficult job, various tools are available for API testing a few of them are:-
API is a powerful web component, and businesses of all kinds are embracing it because of the following advantages:-
API documentation is like a deliverable. Technical content deliverables such as API documentation provide guidance on how to use and integrate APIs. It is a brief reference guide that includes all the details needed to use the API, including information on the functions, classes, return types, arguments, and more, all backed up with tutorials and examples. Traditionally, text editors and common content creation and maintenance tools have been used to create and maintain API documentation. Technical writing that describes the API is also known as API documentation. It contains guidelines for properly utilizing and integrating the API. The lifecycle of the API is also updated, including any new versions or retirements. Using Swagger or other documents, some portions of API documentation can be automatically generated.
The test cases that are run repeatedly during each sprint, such as regression cases, frequently need to be automated. Similar to this, there are several API testing scenarios that we must run before each release; these scenarios should be automated, and this is what we call API automation. We use various tools like SoapUI, apigee, etc., for API automation. The automatic creation of an API connecting two previously unconnected applications or services is the first application for API automation. If you can even find a competent API developer in the first place, manually developing an API can be a highly specialized and time-consuming project depending on the use case and technological complexity. With a project timetable of a few weeks or months, estimations for the cost of developing an API can rapidly reach the thousands and thousands of dollars range. Additionally, if the underpinning services change, these estimates do not take ongoing maintenance and support into consideration.
Web services and APIs are frequently confused with one another. They may carry out most of the same tasks, but they are not exactly the same. Let's examine both of these before moving on to their distinctions.
API needs a network to function sometimes
Web services always need a network to function.
SOAP, REST, CURL calls, and XML is used for communication in API
SOAP, REST, and RPC is used for communication by web services
Not all APIs are web services
All web services are APIs
Example: amazon API
Example: .NET SDK
The first digit of the Status-Code element in a server response specifies the response class, and the last two digits play no part in classification. The Status-Code element are combination of 3 integers. A server responds to a request from a client by returning a status code. It includes codes from various specifications, IETF Request for Comments (RFCs), and some extra codes used in some widespread HTTP applications. One of five standard response classes is indicated by the status code's first digit. The normal message sentences that are displayed can be replaced with any human-readable alternative. The status code is a component of the HTTP/1.1 standard unless otherwise stated (RFC 7231).
Example: The error message "Page not found" will appear if the firm ABC changes its name to "ABD" and the user inputs the same old URL that has not yet been changed to the new company name. The code that pops up on the screen is the status code. Like error “404”.
There are a total of 63 status codes, but they are divided into 5 categories, and codes from each category are used for a different domain. The five categories are:-
The capacity factor of a package or other data transmission unit is referred to as a payload in computing. The phrase, which has military roots, is frequently used in relation to malicious code that can be executed and cause harm. Data payload and malware payload are two different types of payloads that are used to attack and corrupt IT networks and systems, respectively. Data payload refers to the movement of data through a network.
Programmers use the term "payload" to distinguish between the information that is necessary for a piece of data and the information that is used to support it. Secured input data is supplied to the API as the payload/body in order to process the request. In the REST API, the payload is often built in JSON format.
API stands for application programming interface, it acts as a connecting link between a computer and its programs. It is a type of software interface that allows applications to access the data and interact with operating systems, software components and microservices. In simple terms, an API is responsible for sending the user's response to the system and bringing back the system's response to the user. APIs are used in web development both backend and frontend.
From this picture, we can understand how an API works. We can see how the API is accessing data from the database and making the communication between operating systems, computer programs and software components possible.
API has been used in various technical projects by very prominent technological organizations. Some examples are Google Maps API, YouTube API, Amazon advertising API, etc. In the Google maps API project, navigation data from satellites was stored in the Google maps database and it was sent to the application with the help of an API. In the YouTube API, data from YouTube surveys and history was stored in the YouTube database and was then shared with the application with the help of API and was later used to curate YouTube videos and advertisements recommendations. Similarly in Amazon advertising API, data from customer history and orders were stored in the Amazon database and was provided to the software via API and was later used to curate tailor-made advertisements and product recommendations for each customer. In each project, the customer data collected by various surveys and research were stored in the database and were then provided to the software. The smooth communication that we witnessed in all the programs was due to the API.
Indeed, people often get confused between API and web services, these two terms even overlap many times, but API and web services are two very different terms. An API acts as an interface between computer and computer programs, it is responsible for accessing data on various databases and sending it as a response to the computer applications, software, operating systems, and microservices. Whereas, a web service is a software system and is responsible for the machine-to-machine interaction that takes place on a network. In simple terms, web service is a resource that is available on the internet. People get confused between an API and a web service because all web services are an API, but not all APIs are web services.
The major point of differences between an API and a web service are: -
Note: We will study in detail REST in the advanced interview questions and will cover REST assured API testing interview questions and REST API automation interview questions.
No, it is not true that there are limited options for API testing. API testing methods are wide and varying. A few methods to test an API are: -
Protocols indeed are an integral part of every digital system, Protocols are the set of rules that define how applications interact with each other. Protocols are a significant part of any API system since Protocols are responsible for interaction and communication. Protocols play a significant role in API testing as well.
The various protocols used in API are: -
It is indeed true that API testing is a lengthy and rigorous process, there are many ways by which we test an API. We test an API because it is essential to do so and there are many advantages of testing an API.
A few advantages of API testing are: -
There are 5 significant principles involved in the API test design and they are as follows:-
Yes, there is a procedure that we need to follow when we are performing API testing. It involves some fundamental steps, which are:-
When we are performing API testing, there are a couple of things that we check. We check those things by raising a request to the API with the known data, and we analyze the validation response in this manner.
The basic things that we check during testing an API are: -
API testing indeed has major advantages, but this does not mean it is bereft of any challenges. We face many challenges while API testing, few of them are: -
Various testing methods come under API testing, a few of them are: -
To understand the difference between the two, we first need to understand what these two terms are individually. Structured data can be shared in a decentralized, distributed environment thanks to the broad messaging infrastructure defined by the SOAP standard communication protocol system, which employs XML technologies. In other words, SOAP enables the use of different technologies and computer languages for communication between applications running on various operating systems. On the other hand, REST is an architectural approach rather than a protocol. It stands for Representational State Transfer, as was already mentioned. This means that when a client uses a REST API to access a resource, the server sends back the resource's current state in a common format. In other terms, REST APIs respond to requests for resources by returning all pertinent data in a way that customers can easily understand.
SOAP stands for simple object access protocol
REST stands for representational state transfer
SOAP is a protocol
REST is an architectural pattern
SOAP uses WS and SSL (Secure socket layer) for security purposes.
REST uses SSL(Secure socket layer) and HTTPS for security purposes.
SOAP uses and supports only HTTP and XML
REST uses and supports multiple data formats like, HTML, XML, JSON, plain text, etc., but JSON is the most preferred data format.
POSTMAN API testing interview questions should be done with utmost care and priority since questions from this topic are asked very frequently in various interviews.
An HTTP Client-based program called Postman is mostly used to test APIs. The GUI (Graphical User Interface) can be used to test HTTP queries, and the outcomes can be examined. Providing a platform for designing, implementing, testing, and documenting APIs, also makes it easier for team members to collaborate on API development.
For testing purposes, using Postman eliminates the need to create any HTTP client network code. Instead, we create collections of test cases and let Postman communicate with the API.
A collection is a set of data objects that must be worked on collectively in a controlled manner and have some shared value to the problem being solved. In computer programming, a collection is a gathering of a variable number of data items (potentially zero). The data items will typically be of the same type or, in languages that permit inheritance, derived from a type that has a common ancestor. Although there is frequently a traditional option, a collection is a concept that applies to abstract data types and does not dictate a specific implementation as a physical data structure. The term “collection” in API is related to POSTMAN. In Postman, a collection is a bunch of API requests that have previously been saved and can be organized into folders. A collection can have any number of folders. The client's demands are better organized and documented when they are placed in folders and collections.
Each API request can be saved and organized into a collection, which can then be shared among the team members in the Postman workspace.
Such questions are very common in API testing POSTMAN interview questions, practicing them would be favourable for users appearing for interviews.
Monitoring is a method for maintaining tabs on the functionality and health of APIs. We can keep track of API performance and development thanks to Postman's built-in monitoring features. The operation of the collection runners is the main focus of Postman's monitors. They execute each request in the collection and examine the test script values. The test scripts are used by the monitors to verify and keep track of the responses. Depending on our setting options, the reports produced are sent to the developers via emails or alerts in Slack, Hipchat, and other platforms.
An implicit or explicit caching mechanism is a technique for temporarily storing data and retrieving it from a high-performance data store. By making a copy of the requested asset and retrieving the cached copy later rather than the original, caching mechanisms enhance performance. Cache memory is allocated its own partition in RAM. Cache memory determines whether the requested data is already available in it before requesting it from storage on behalf of a software program. The application will read this data from the cache if it is present there. The software application will ask for the source if the necessary data isn't present in the cache memory. The same information is kept in cache memory for later use after reading it.
A framework is exactly what it sounds like. A framework,as the name suggests contains code, structure, processes, classes, and functions that have previously been established in the API. Any programming language, including PHP and Python, can make use of the framework in API. Any software created with the aid of a framework must adhere to its restrictions it lays down. An operating system may support a framework. The Android framework will be used if you're creating an Android application. As an alternative, some operating systems need particular frameworks to function, such as a Microsoft.Net framework for the Windows system.
A framework may include code libraries and APIs from which an app can draw data. A library is a collection of codes that are used to streamline or organize tasks. A particular language's constants, classes, functions, and procedures help programmers write less code. You will search the library for information. The framework serves as the backbone on which the library or libraries are supported. They both specify an API that programmers can utilize. We might conceive of a library as a specific application function, a framework as the foundation of the program, and an API as the connector to connect things in order to put them all together. A normal developmental process often begins with a framework and uses the API to complete functions described in libraries.
The act of stimulating user input is referred to as input injection. Windows applications can route input anywhere, including beyond the client area, by using input injection to simulate input from a number of input devices. Even to the applications running with Administrator privileges. For Windows apps and solutions that need to offer functionality such as accessibility, testing, ad hoc, automated, and remote access and support capabilities, input injection is helpful. There are several approaches to imitate user input, including:
We work without relying on Postman servers due to the workspace Scratch Pad, which is supplied by Postman. It enables us to use some of Postman's features even while you are not online. The capabilities include adding requests, adding collections, and adding requests. These are kept locally, and once you log in, the work is saved in the workspace. It is a tool that has made API testing and automatio easier than ever. Very few tools can be used offline for API testing and API automation. The offline working feature helps the users to get away with the biggest problem of server crashing. Even when postman server crash, we can easily use the ScratchPad API tool.
One of the fundamental tenets of REST design is statelessness. The server does not save any records of prior communications in stateless communication. In other words, neither the client nor the server are aware of the other's condition. Each interaction between a request and a response is unique, and each request contains all the information a server needs to deliver a successful answer.
Because the server does not need to expend space or resources to store data from previous requests in order to handle requests in the future, statelessness makes client-server interactions simpler. Every HTTP request occurs in total isolation due to statelessness. When a client sends an HTTP GET request, it contains all the data the server needs to process it. The information from a client's prior queries is never used by the server. If any of this information is crucial, the client will include it in the current request.
POST and PUT are comparable but not identical. PUT replaces a resource at a specified URI with another resource, whereas POST creates a resource on the server. When you use PUT at a URI when another resource already exists, PUT will replace that resource. PUT creates a resource if there is none at the given URI. PUT is also idempotent, which implies that using it more once will only produce one resource. This is so because every call substitutes the current resource (or creates a new one if there is nothing to replace). POST lacks idempotence. Additionally, this indicates that PUT responses cannot be cached, in contrast to POST responses.
"Create, Read, Update, Delete" is the acronym for CRUD. These are the four fundamental operations that a REST API can execute on databases. Each action is matched with a specific HTTP request method:
Every piece of server-side content that may be accessed is known as a resource in REST architecture in API. An object with a type, associated data, a connection to other resources on the server, and a set of methods that may be used with it is referred to as a resource. An executable code file, a picture or video, a data file, an HTML or text file, or other types of API files are examples of resources. A uniform resource identifier, or URI, is used to identify resources. Clients use the URIs of resources in HTTP requests to access them.
A unified resource identifier is referred to as a URI. A URI in REST is a string that designates a web server's resource. Each resource has a distinct URI that, when used in an HTTP request, enables clients to target it and do actions on it. Addressing is the process of directing traffic to a resource using its URI. People often get confused between URI, URL, and URN. How can we distinguish between URIs, URLs, and URNs?
The usage rules for APIs typically include things like copyright, storage, and display standards. APIs are only created using business logic and this varies from business to business.
The entire application will probably suffer from the new API version. Implementing a change is frequently elevated to risk due to the numerous dependent components and uncertain executions. Hence changes are brought in very carefully.
APIs are all about data, and since constructive testing includes many factors, it requires additional data. For API testers, it can be difficult to manage such a large amount of data and make sure that it can still be used.
Statelessness can be both an advantage as well as a disadvantage of REST API,it mostly depends on the function or process that a user has to carry out. But if we talk generally, Statelessness can be a benefit of REST API for some, but it can also be a drawback. The state of an API is not preserved through REST API. In other words, the server doesn't save a history of previous communications. If maintaining a state is required, the client is responsible for doing so. Developers must exercise caution and only use APIs from reliable, authentic providers as REST has less stringent security controls than SOAP. REST is therefore a bad choice for transmitting private data between servers and clients.
Engineers and analysts can create testing tools and automated tests for.NET and Win32 programs using the Test API, a suite of test and utility APIs. The test building blocks kinds, information constructs, and calculations are provided by the test API in a simple, layered, componentized, and archived stack. Test API is often used because:
There are three layers in Test API:
Before sending the modifications to the production environment, shrewd businesses test API for convenience. Testing in both staging and development environments is important to verify that the software program complies with requirements. The following are some rewards of testing APIs:
Since REST APIs don't use as rigorous security safeguards as SOAP APIs, sensitive data shouldn't be sent or retrieved using them. However, trustworthy REST APIs continue to integrate security controls for safe and dependable data transmissions.
Digestion Authorization is related to POSTMAN API, this concept is a part of API testing using POSTMAN interview questions. As a choice for authorization, Postman offers the Digest Authorization technique. The server replies with a number that can only be used once, a realm value, and a 401 unauthorized response code once the client sends the request to the API. The login, password, and the information we previously obtained from the server are all included in an encrypted data array that we get. To authenticate the request, the server creates an encrypted data string from this data and compares it to what was sent. By navigating to the Authorization tab and choosing "Digest Auth" from the drop-down menu, you can accomplish this. The Postman window shows the fields for both phases of the authentication request.
API requests should be made in chronological order that matches the functionality. For instance, before placing an order, the product must first be placed in the shopping basket. Logging onto the website, searching for the product, choosing it, adding it to the cart, and placing an order are the steps in the call chain. Any inconsistency in the order of API calls causes the system's functionality to change because the output of one API is the input for the next one. When multithreaded programs are involved, this complexity increases. Each time a feature changes, validate these sequences. The set of instructions needed to transfer a command to a subroutine or process includes supplying parameters and storing the return address. If it is necessary to call processes written in a variety of languages from the calling program, consistency of calling sequences is essential.
The data that is transferred between these systems serves as the medium for communication between API & systems. The parameters have been given this data, and it is essential to verify the parameters using the data. The operation of API systems depends critically on the evaluation of the parameters. You must build every configuration with conceivable parameter combinations and evaluate various scenarios. Consider the type of data the parameter uses, if it fits within the assigned length/range, whether it passes another validation, etc. while validating these parameters. A good test case coverage can be achieved using boundary value combinations, equivalent partitions, pair-wise testing tools, and constraint-based elimination strategies. Additionally, you can use continuous API Monitoring Systems, which will provide speedy confirmation of system faults.
The test documents' API syntax and grammar are defined by the schema, which acts as a template for these elements. So we can check to see if a document is valid when a schema is appropriately applied to an input document. When using a mock server, documentation, tests, or monitors to validate the response parameters, you must set up the appropriate schema. We must update the schema if there is a change to the API document, such as the addition of new features or the upgrading of current ones. Throughout the testing phase, keep doing this.
Both API testing and Unit testing are testing methods, but both of them are strikingly different from each other.
API testing is concerned with the final output of the system which is under test.
Unit testing is concerned with the functionality of the module of the system which is under test.
API testing is executed solely after the build of the system is fully ready.
Unit testing is accomplished when the unit test code or test script is written by the developers.
API testing portrays the system as a whole as it is the user interface and it interacts with the end-user.
Unit testing tries to portray each module in isolation and checks if each module is functioning properly as a single entity.
It is factual that both API testing and UI (User Interface ) testing deal with multiple interfaces but these two are strictly distinct from each other.
API testing enables the communication between two or more separate software systems. Whereas, in UI testing we test the graphical interface and see how users interact with it.
If we were to explain it to a person from a non-technical background we can explain API testing as the communication or exchange of data that takes place between two different software. And UI testing is when a user interacts with the graphical part of any interface, like when we see various fonts, graphics, etc. whenever we open a website.
In today's time, the most suitable form of automation testing is API testing, and it has replaced GUI testing a long time ago. Developers all across the world prefer API testing over any other form of automation testing. It is considered to be the most suitable form of automation testing because:-
REST stands for Representational State Transfer. It is an architectural style that is used for developing web services, it is known to exploit the all-presence or ubiquity of HTTP. The main focus of REST is on the resource, it can be accessed through any shared interface. REST server provides access to resources and the REST client makes them obtainable.
REST architecture refers to any sort of content as a " resource". The content comprises anything, it can be text, graphics, dynamic information, etc. REST uses distinct representations to define any resource. XML and JSON are the most popular ones.
There are 5gettingy components in any HTTP request: -
Some of the most commonly used methods of HTTP requests that are supported by REST are: -
SOAP stands for Simple Object Access Protocol. It is defined as an XML based protocol. It is used in designing and developing web services and it is known to enable the communication between applications. Since it is both platform and language independent, it can communicate between applications designed and developed on different platforms using different programming languages.
Various facilities are provided by SOAP protocol like:-
Postman is an HTTP client-based software and is widely used in API testing. It is known to support the testing of HTTP requests by simultaneously utilizing the GUI ( Graphical user interface). It provides a platform for designing, developing, testing, and documentation APIs and it is used by developers for the development of APIs.
Note:- API testing postman interview questions are asked very frequently by job interviewers.