API INTERVIEW QUESTIONS AND
ANSWERS WITH SOLUTIONS 2024
What is an API? - ANSWER An application programming interface (API) allows application developers to
bypass traditional web pages and interact directly with the underlying service through function calls. It's
s a software intermediary that enables two applications to communicate with each other. It comprises a
number of subroutine definitions, logs, and tools for creating application software.
In an API testing interview, you could be asked to give some API examples, here are the well-known
ones: Google Maps API, Amazon Advertising API, Twitter API, YouTube API, etc.
What are main differences between API and Web Service? - ANSWER All Web services are APIs but not
all APIs are Web services.
Web services might not contain all the specifications and cannot perform all the tasks that APIs would
perform.
A Web service uses only three styles of use: SOAP, REST and XML-RPC for communication whereas API
may be exposed to in multiple ways.
A Web service always needs a network to operate while APIs don't need a network for operation.
What are the Limits of API Usage? - ANSWER Many APIs have a certain limit set up by the provider. Thus,
try to estimate your usage and understand how that will impact the overall cost of the offering. Whether
this will be a problem depends in large part on how data is leveraged. Getting caught by a quota and
effectively cut-off because of budget limitations will render the service (and any system or process
depending on it) virtually useless.
What are some architectural styles for creating a Web API? - ANSWER This is one of the fundamental
Web API interview questions. Bellows are four common Web API architectural styles:
HTTP for client-server communication
XML/JSON as formatting language
Simple URI as the address for the services
Stateless communication
,Who can use a Web API? - ANSWER Web API can be consumed by any clients which support HTTP verbs
such as GET, PUT, DELETE, POST. Since Web API services do not require configuration, they can be easily
used by any client. In fact, even portable devices such as mobile devices can easily use Web API, which is
undoubtedly the biggest advantage of this technology.
What is API Testing? - ANSWER API testing is a kind of software testing which determines if the
developed APIs meet expectations regarding the functionality, reliability, performance, and security of
the application.
What are the advantages of API Testing? - ANSWER Test for Core Functionality: API testing provides
access to the application without a user interface. The core and code-level of functionalities of the
application will be tested and evaluated early before the GUI tests. This will help detect the minor issues
which can become bigger during the GUI testing.
Time Effective: API testing usually is less time consuming than functional GUI testing. The web elements
in GUI testing must be polled, which makes the testing process slower. Particularly, API test automation
requires less code so it can provide better and faster test coverage compared to GUI test automation.
These will result in the cost saving for the testing project.
Language-Independent: In API testing, data is exchanged using XML or JSON. These transfer modes are
completely language-independent, allowing users to select any code language when adopting
automation testing services for the project.
Easy Integration with GUI: API tests enable highly integrable tests, which is particularly useful if you want
to perform functional GUI tests after API testing. For instance, simple integration would allow new user
accounts to be created within the application before a GUI test started.
Some common protocols used in API testing? - ANSWER Many protocols are now available to be used in
API testing, such as JMS, REST, HTTP, UDDI and SOAP.
What is the test environment of API? - ANSWER Setting up the API's test environment is not an easy task,
so you should have a ready answer if your API testing interview is coming. The test environment of API is
a bit complete and requires the configuration of the database and server, depending on the software
requirements. No GUI (Graphical User Interface) is available in this test form.
When the installation process is complete, API is verified for the proper operation. Throughout the
process, the API called from the original environment is set up with different parameters to study the
test results.
, What are principles of an API test design? - ANSWER The five most important principles of an API test
design are:
Execution: Steps to apply API or the scenario, including logging
Verification: Oracles to evaluate the result of the execution
Reporting: Pass, failed or blocked
Clean up: Pre-test state
What are the common API testing types? - ANSWER While there are certainly specialty tests, and no list
can be asked to be comprehensive in this realm, most tests fit broadly into these following nine
categories that you should remember before attending in an API testing interview.
Validation Testing
Functional Testing
UI testing
Load testing
Runtime/ Error Detection
Security testing
Penetration testing
Fuzz testing
Interoperability and WS Compliance testing
What is the procedure to perform API testing? - ANSWER Choose the suite to add the API test case
Choose the test development mode
Demand the development of test cases for the required API methods
Configure the control parameters of the application and then test conditions
Configure method validation
Execute the API test
Check test reports and filter API test cases
Arrange all API test cases
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