API definition and API Testing
Application Programming Interface(API)
is defined as a collection of software procedure and functions. This
API can be used by other software..
What is API Testing?
API testing is highly used for testing
those systems which contains collection of API. For example that
system may be Application software, system software or libraries. This testing is very
different from GUI based testing. In spite of GUI testing does not
come under API testing but even though we need to set up initial
phase environment and also we need to
call API with set of parameters and then analyzing the output. There
is some complexity in setting up initial environment due to absence of GUI. For API testing you
have to be sure that all are set up and systems are ready to be
tested. Later it is divided in Application setup and test
environment. setting up the environment
involve some work like database configuration, server running and
regarding test environment. on another side make sure that object is properly initialized before
calling their non static members of that class and it comes under
application setup. Under initial setup also we need to create some conditions under which API will is
called. Perhaps API is called directly or it should be called in
responded of some exception.
Test Cases Involved in API Testing:
Test cased are generated based on
output.
1)based on Return value of input
condition
This test is based on input we give and
we validate the output on the basis of input. Writing test case for
some some king of API like int add(int a, int b) is very easy. You pass multiple combinations
for a and b and validate the output.
2)Trigger some other
API/event/interrupt
The result of API if fires some event
or produce some interrupt, then they should be tracked. Test suite
supposed to call related API and declarations is based on interrupts and listener
3)Does not return anything
We need to check the behavior of
software of system if nothing is returned.
For example:- If we have to delete list
element and then we require to validate absence of list element and
its size in the list.
4)Update data structure
This category is related to that
category which nothing returns, On update of data structure offcourse
will effect system that need to be validated.
5)Modify certain resources
If API call effects some resources like
changing registry, killing process, updating database then it should
be validated.
API Testing vs. Unit Testing: What’s
the difference?
1)API testing is different from unit
testing and owned by QE team and development team. Unit testing known
as white box testing and API testing is known as black box testing.
2)Similarity between these two is both
target code-level so using same type of tool for both type of
activity. There are several tools which are open source for API testing for example HttpUnit,
Webinject, XMLUNIT, etc.
3)API test involves methods of 2EE
APIs, JAVA, DOTNET etc and also test these API for Application
servers.
4)development team owns the unit
testing and the developers are supposed to create unit test for each
code module for example stored procedures, functions, classes, etc and also confirm that these module
pass its own unit test before code is build. On the other and API
testing are owned by QE team and its staff. API test is normally run after build is confirmed
to be ready and the common thing is authors of test is not given
access to source code, they build black box testing in respect to API.
5)Another difference between these two
testing type is test case design. Unit test is designed for
verification of each unit under isolation behaves as it is supposed. If we talk about scope of these
testing then unit testing does not consider system level functions of
various units. while API test, specially designed for considering the whole functionality of
the software system as it is going to be used by end user so API
testing is more extensive in comparison to unit test and supposed to take sorts of scenarios
which API will be used for and typically include transactions between
many modules with in application.
API Testing Approach
An approach for testing Product
which an API contains.
Step I) API testing required some
coding and normally is beyond the scope of what developer is expected
for doing. This activity should be owned by Testing team.
Step II) Some traditional testing is
also applied to API testing like equivalence classes, boundary
analysis etc. Thus whatever you are not good in coding but still you can design API test.
Step III) As we know it is impossible
to test whole scenarios so mostly focus on important scenarios and
apply some techniques for example soap opera testing and also try forced error testing by using
multiple data types and different size. Challenge of API testing is
divided in to below given categories
a)Call sequencing
b)Parameter combination
b)Parameter combination
c)Parameter Selection
API Framework
This framework is self-explanatory.
Config file is used for holding the configurable parts and there
values for test run. Automated test cases must represent in "parse - table" format within config
file. This script must be effectively configurable. When API testing,
it is not essential to test each API so the config file have some
sections whose all API are made
activated for that specific run. Test cases are picked up based on
it. Although it is very tedious to include
test case parameters in config file but it must be designed in this
way that test case is left static with the facility to 'activate' and 'deactivate' them
Definitions:
Soap Opera Testing:
This test is exaggerated and made to
complicate scenarios in such a way that television soap operas are
made to exaggerate and to complicate real life
Forced Error Testing:
It is same as mutation testing. Its the
way of inducing changes/errors for the application to explore how
application is supposed to be working. FET (forced-error- test) contains negative cases which is
designed to force a program unit into error condition. All the error
messages should be generated by this program in the form a list. This list is very important and
is baseline for development test cases.
Software Functions and Procedures:
Procedures and functions are the base
of program. They facilitate the structure to build a program into
small logical units which become easy to manage and it can manage various activities needed by
program
Functions
There are basically two types of
functions:
Built-in
this type function are already provided
with the system and they are supposed to do some operations like
printing, writing, opening and closing files, converting variables etc.
Application/user-specific
As per requirement of the program you
can create procedures and functions by using built-in system
procedures, functions and variables.
Procedures
Procedures are supposed to do series of
tasks. Normally they combine other functions and procedures within a
program. Main difference between procedure and function is procedure does not return value. It is
executed and control come back to calling subroutine or procedures.
In Visual Basic it is called "Subroutines" and "Sub"
in short. "Function" is used
like procedures in JavaScript it return null or no value to whatever
they called by.
FOLLOWING ARE THE TIPS AND QUEST. / ANS. ON THE API AND API TESTING:
What is API and API Testing?
API: Stands
for Application Programming Interface.
An API actives the communication in between two different -2
software application system. Application implementing an API contains methods /
sub-routines, which can be called by another application software. Then Finally
API’s are functions which are used in one application and can be executed by
another application.
API Testing: Testing the interface of application
programming of any system software.
Simple requirement of API Testing is, API function need to call from the
Calling application. It required database, server, application setup and all
necessary test environment.
API test cases perform to check the functionality of the
application related to business logic. This is totally different to GUI
Testing. Test engineer doesn’t test the look and feel of application software
in this testing.
 |
| API and API Testing |
Test Cases for API environment and set – up: Set up
of API environment is complicated as there is not any interface to test. According
to software requirement, database and server should be configured. Execution of
API function is used to check whether that API is working or not.
API output can be:
i.
Any type of record (data)
ii.
Pass or Fail – Status
iii.
Call to another / next API function.
Output always compared with expected outcome. API test cases
created on the base of input data.
Example: API function adding two numbers:-
i.
Long add(int r, int s)
Here numbers will be provided as input and output should be
submission of these provided two integers. And this output should match and
verified with expected result.
i.e. add (6789, 1235)
Let’s check following API Functions-
i.
Delete()
ii.
Lock()
iii.
Unlock()
Above functions will return the values such as True (If
pass) and False (If Failed) in output. These functions can be used anywhere
and also can call from anywhere.
Calling to another API / Event: Here our application
will call one API function and that API function will call another one
function.
EXAMPLE: Delete function in database will call by our
application then another one function REFRESH the database will be called
automatically.
API Testing Approach:
i.
API program functionality needs to
understand so that clearly decided the scope of testing.
ii.
Boundary value analysis, error guessing
and equivalence classes techniques need to applied and creating the test cases
for API.
iii.
Input data or record need to properly
planned and defined correctly, Mean input value should be valid.
iv.
Now execute the test cases and check the
output with expected output.
Difference Between API and Unit Testing:
 |
| Difference between Unit and API Testing |
Automation of API Testing:
Following automation tool can be used for API Testing-
i.
NUnit for .Net
ii.
JUnit for Java
Best Practices of API Testing:
i.
Planning and organize the test cases
properly and appropriately
ii.
All parameters should be explained
properly in the test case
iii.
Call sequencing and Prioritize API
functions
iv.
Testing should be proper
API Testing Challenges:
i.
GUI is not available to test any
application
ii.
Validating and Verifying the output
iii.
Parameters categorization and selection
iv.
Proper Exception Handling
v.
Test Engineer should have knowledge of
code
Learn API software testing in 10 minutes, what are API and
API Testing, definition, test cases, best practices, real world scenarios,
challenges, approach, example and process of api testing, Automation of API
Testing, Difference Between API and Unit Testing
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