Integration testing
Satish Mishra
mishra@informatik.hu-berlin.de
This session
! Integration testing
! Component / Module testing
! Stub and driver
! Examples
! Different approaches to integration testing
! Bottom-up
! Top-down
! Big-bang
! Sandwich
! Exercise
! Discussions
Satish Mishra Integration Testing 2
What is integration testing
! Testing in which software components, hardware
components, or both together are combined and tested
to evaluate interactions between them
! Integration testing usually go through several realword
business scenarios to see whether the system can
successfully complete workflow tasks
! Integration plan specifies the order of combining the
modules into partial systems
Satish Mishra Integration Testing 3
Figure 1-2
Transactions in Electronic Markets
Satish Mishra Integration Testing 4
Component / Module testing
! A unit is the smallest testable piece of software. A unit
is defined as a database trigger, stored procedure,
function, report, form, batch load program or PL/SQL
program.
! Unit testing is the testing that is performed to validate
that the unit does satisfy its functional specification
and/or that its implementation structure does match
the intended design structure.
! Module /Component consists of units integrated into a
module that performs a specific business function
Satish Mishra Integration Testing 5
Testing Activities
Subsystem Requirements
Unit System
Code Test Analysis
Design Document
Tested Document User
Subsystem
Subsystem Manual
Unit
Code Test
Tested Integration
Subsystem Functional
Test Test
Integrated Functioning
Subsystems System
Tested Subsystem
Subsystem Unit
Code Test
Satish Mishra Integration Testing 6
Drivers and Stubs
! Driver: A program that calls the interface procedures
of the module being tested and reports the results
! A driver simulates a module that calls the module currently being
tested
! Stub: A program that has the same interface
procedures as a module that is being called by the
module being tested but is simpler.
! A stub simulates a module called by the module currently being
tested
Satish Mishra Integration Testing 7
Drivers and Stubs
Module
Driver Stub
procedure Under Test procedure
call call
Satish Mishra Integration Testing 8
Example 1:
! We now consider an example in which we need to
develop a "calculator" that converts between different
units (e.g., feet to inches).
! We will implement in java !!
! Class UnitConverter
! Method convert
! Method getMultiplier
! Class Driver
! Method main
Satish Mishra Integration Testing 9
public class UnitConverter
{
public UnitConverter() // Not writing comments since we don’t have place..
{
}
public double convert(double value, String from, String to)
{
Soln.. double result;
result = value * getMultiplier(from, to);
return result;
}
public double getMultiplier(String from, String to)
{
double multiplier;
multiplier = 1.0;
if (from.equals("inches")) {
if (to.equals("feet")) multiplier = 1.0/12.0;
else if (to.equals("yards")) multiplier = 1.0/12.0/3.0;
else if (to.equals("miles")) multiplier = 1.0/12.0/3.0/1760.0;
} else if (from.equals("feet")) {
if (to.equals("inches")) multiplier = 12.0;
else if (to.equals("yards")) multiplier = 1.0/3.0;
else if (to.equals("miles")) multiplier = 1.0/3.0/1760.0;
} else if (from.equals("yards")) {
if (to.equals("inches")) multiplier = 3.0*12.0;
else if (to.equals("feet")) multiplier = 3.0;
else if (to.equals("miles")) multiplier = 1.0/1760.0;
} else if (from.equals("miles")) {
if (to.equals("inches")) multiplier = 12.0*3.0*1760.0;
else if (to.equals("yards")) multiplier = 1760.0;
else if (to.equals("feet")) multiplier = 3.0*1760.0;
}
return multiplier;
}
}
Satish Mishra Integration Testing 10
public class Driver
{
Soln.. public static void main(String[] args)
{
double converted, original;
int i, j;
String from, to;
String[] units = {"inches","feet","yards","miles"};
UnitConverter calculator;
calculator = new UnitConverter();
original = 10.0;
for (i=0; i < units.length; i++) {
for (j=0; j < units.length; j++) {
from = units[i]; // This could be outside the inner loop
to = units[j];
converted = calculator.convert(original, from, to);
System.out.println(original+" "+from+" = "+converted+" "+to);
}
}
}
}
Satish Mishra Integration Testing 11
How to test this system ??
Embedded Controller
Analysis
and
Control Com Port
Software Heart support device
Patients
Database
.
Satish Mishra Integration Testing 12
Integration testing approaches
! Different approaches to integration testing
! Bottom-up
! Top-down
! Big-bang
! Sandwich
Satish Mishra Integration Testing 13
Artifacts and Roles for Integration Testing
Test Component Integration System
engineer engineer tester tester
. . . . . . . . . . . . . . . . . . responsible for . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Test
Use-case
model Test Test
evaluation r
plan procedure Test Defect
Test case component management
Satish Mishra Integration Testing 14
What we have here…
! Developers do everything they can to make the
software work.
! Testers do everything they can to make the software
fail.
Satish Mishra Integration Testing 15
Bottom-Up Integration
! Only terminal modules are tested in isolation
! Modules at lower levels are tested using the previously
tested higher level modules
! This is done repeatedly until all subsystems are included in
the testing
! Requires a module driver for each module to feed the
test case input to the interface of the module being
tested
! However, stubs are not needed since we are starting with the
terminal modules and use already tested modules when testing
modules in the lower levels
! Disadvantage: Tests the most important subsystem last
Satish Mishra Integration Testing 16
Bottom-up Integration
A B
C H
E F G I
Satish Mishra Integration Testing 17
Top-down Integration
! Only modules tested in isolation are the modules which
are at the highest level
! After a module is tested, the modules directly called by
that module are merged with the already tested
module and the combination is tested
! Do this until all subsystems are incorporated into the test
! Requires stub modules to simulate the functions of the
missing modules that may be called
! However, drivers are not needed since we are starting with the
modules which is not used by any other module and use already
tested modules when testing modules in the higher levels
Satish Mishra Integration Testing 18
Top-down Integration
A B
C
H
E F G I
Satish Mishra Integration Testing 19
Sandwich Testing Strategy
! Combines top-down strategy with bottom-up strategy
! The system is view as having three layers
! A target layer in the middle
! A layer above the target
! A layer below the target
! Testing converges at the target layer
! How do you select the target layer if there are more than 3
layers?
! Heuristic: Try to minimize the number of stubs and drivers
! Top and Bottom Layer Tests can be done in parallel
! Does not test the individual subsystems thoroughly before
integration
Satish Mishra Integration Testing 20
Other Approaches to Integration
! Big Bang Integration
! Every module is unit tested in isolation
! After all of the modules are tested they are all integrated
together at once and tested
Satish Mishra Integration Testing 21
Implementation Approaches
Advantages and Disadvantages
! Big bang advantages ! Big bang disadvantages
! None ! Difficult to debug
! Much throwaway code
! Critical and peripheral modules not
distinguished
! User does not see product until
very late in the development cycle
Satish Mishra Integration Testing 22
Implementation Approaches
Advantages and Disadvantages
! Top-down advantages ! Top-down disadvantages
! Separately debugged modules ! Stubs must be written
! System test by integrating ! Low-level, critical modules built last
previously debugged modules ! Testing upper-level modules is
! Stubs are easier to code than difficult
drivers
! User interfaces are top-level
modules
Satish Mishra Integration Testing 23
Implementation Approaches
Advantages and Disadvantages
! Bottom-up advantages ! Bottom-up disadvantages
! Separately debugged modules ! Drivers must be written
! System test by integrating ! Upper-level, critical modules are
previously debugged modules built last
! Testing upper-level modules is ! Drivers are more difficult to write
easier than stubs
! User interfaces are top-level
modules
Satish Mishra Integration Testing 24
Summary of testing
! Verify operation at normal parameter values
(a black box test based on the unit’s requirements)
! Verify operation at limit parameter values
(black box)
! Verify operation outside parameter values
(black box)
! Ensure that all instructions execute
(statement coverage)
! Check all paths, including both sides of all branches
(decision coverage)
Satish Mishra Integration Testing 25
Summary of testing
! Check the use of all called objects
! Verify the handling of all data structures
! Verify the handling of all files
! Check normal termination of all loops
(part of a correctness proof)
! Check abnormal termination of all loops
Satish Mishra Integration Testing 26
Summary of testing
! Check normal termination of all recursions
! Check abnormal termination of all recursions
! Verify the handling of all error conditions
! Check timing and synchronization
! Verify all hardware dependencies
Statements of (Watts Humphrey)
Satish Mishra Integration Testing 27
Exercise 2.0
! Write the integration test cases for the above system with
the consideration of integration approach .
Satish Mishra Integration Testing 28
Description
! As per the diagram requirement is clear and we should
be able to design the system with our knowledge of
software engineering.
! Consider object / Module oriented design and write the
integration test cases for the system.
Satish Mishra Integration Testing 29
Satish Mishra Integration Testing 30
