What Is API Testing?
                     WHAT IS API TESTING?
WHAT IS API 
TESTING?
o API is an acronym for Application Programming 
Interface.
o In software application (app) development, API is the 
middle layer between the presentation (UI) and the 
database layer.
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EARLIER VALIDATION
o With API testing, once the logic is designed, tests 
can be built to validate the correctness in responses 
and data. 
o We don't have to wait for various teams to finish 
their work or for full applications to be developed — 
test cases are isolated and ready to build 
immediately.
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EASIER TEST 
MAINTENANCE
o UIs are constantly changing and moving around 
based on how they are accessed — browsers, 
devices, screen orientation, etc. 
o This creates a nightmare scenario where tests are 
incessantly rewritten to keep up with the actual code 
in production.
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FASTER TIME TO 
RESOLUTION
o When API tests fail, we know exactly where our 
system broke and where the defect can be found. 
o This helps reduce time triaging bugs between builds, 
integrations, and even different team members. 
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SPEED AND 
COVERAGE
o 300 UI tests may take 30 hours to run. 300 API tests 
could be run in 3 minutes. That means you’ll find 
more bugs in less time, while also being about to fix 
them immediately.
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TYPES OF API 
TESTING
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UNIT TESTING
o While the testing world can be filled with misnomers, 
the easiest way to think about a "unit test" and APIs 
is testing a single endpoint, with a single request, 
looking for a single response or set of responses. 
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CONTRACT TESTING
o Contract testing is a technique which validates that 
two separate systems (such as two microservices) 
are able to communicate. 
o The interactions exchanged between each service 
are captured and stored in a contract which is used 
to validate that both systems adhere to a common 
agreement.
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INTEGRATION 
TESTING
o Integration testing is the most often used form of API 
testing, as APIs are at the center of most 
integrations between internal or third-party services.
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END-TO-END TESTING
o End-to-end testing can help us validate the flow of 
data and information between a few different API 
connections.
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