Integration testing

• Integrate two or more module.i.e. communicate between the modules.

• Follow a white box testing (Testing the code)

Integration Testing - Overview

System DesignModule Spec

Module Test Doc

Test P lanning

IntegrationTest P lan

Tim

e

Sw Developm entDocum ents

TestActivities

TestDocum ents

Integration TestingOverview

Test Execution

Integrated Modules IntegrationTest Report

Test Case DesignTest Environm ent

InstallationIntegration

Test Specification

Integration Testing

• The Big-bang Approach.• Incremental Approach.

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Integration Testing StrategiesTest methodologies may vary but two basic testing

strategies applied:• Test the software in its entirety

– “Big Bang Testing”• Test the software in modules - Unit Tests,

Integration Tests, Systems Tests – “Incremental testing”

• Two strategies for incremental testing– Bottom - up testing (test harness).– Top - down testing (stubs).

• Sandwich Testing

Top-Down Integration Testing• Main program used as a test driver and stubs are substitutes for

components directly subordinate to it.• Subordinate stubs are replaced one at a time with real

components (following the depth-first or breadth-first approach).• Tests are conducted as each component is integrated.• On completion of each set of tests and other stub is replaced with

a real component.• Regression testing may be used to ensure that new errors not

introduced.

Top Down Integration

• Stub is a piece of code emulating a called function

top module is tested with stubs

stubs are replaced one at a time, "depth first"

as new modules are integrated, some subset of tests is re-run

A

B

C

D E

F G

Top down – Advantages & Disadvantages

• Top-down integration supports fault isolation;• Major design flaws show up early. Modules of a

product can be divided into two groups: – The logic modules and operational modules.– By coding and testing the logic modules before the

operational modules, top-down integration will exploit any major design faults early in the development process

• The main disadvantage of top-down integration is that potentially reusable modules may not be adequately tested.

Bottom-Up Integration Testing• Low level components are combined in clusters that

perform a specific software function.• A driver (control program) is written to coordinate test

case input and output.• The cluster is tested.• Drivers are removed and clusters are combined moving

upward in the program structure.

Bottom-Up Integration

• a driver is a piece of code emulating a calling function

drivers are replaced one at a time, "depth first"

worker modules are grouped into builds and integrated

A

B

C

D E

F G

cluster

Bottom-up – Advantages & Disadvantages

• The operational modules are thoroughly tested when using a bottom-up strategy. It also provides fault-isolation, as does top-down integration.

• Major design faults will be left undetected until late in the development, since the logic module are integrated last.

• This may result in large costs in redesigning and recoding substantial portions of the project.

Sandwich Testing• Combine the two so as to capitalize upon

their strengths and minimize their weaknesses

• neither top-down nor bottom-up inplemenetation/integration is suitable for all the modules, the solution is to partition them

Sandwich TestingTop modules aretested with stubs

Worker modules are grouped into builds and integrated

A

B

C

D E

F G

cluster

Top-Down Integration

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top module is tested with stubs

stubs are replaced one at a time, "depth first"

as new modules are integrated, some subset of tests is re-run

A

B

C

D E

F G

Bottom-Up Integration

14

drivers are replaced one at a time, "depth first"

worker modules are grouped into builds and integrated

A

B

C

D E

F G

cluster

System Testing

• Confirms that the system as a whole delivers the functionality originally required.

• Follows the black box testing.

System Testing - Goals

• Incorrect or missing feature• Performance errors• Security errors• User interface errors• Configuration and compatibility• Compliance to required standards

System Testing - Overview

ProductRequirem ents

System Design

Test P lanning

SystemTest P lan

Tim

e

Sw Developm entDocum ents

TestActivities

TestDocum ents

System TestingOverview

Test Execution

Integrated System SystemTest Report

Test Case DesignTest Environm ent

InstallationSystem

Test Specification

System Testing - Overview

• System Tests:– Define test procedures and instructions– Review test plans– Execute test plans– Record results

System Testing - Strategy

• Developing System Tests– stress tests– security tests– recovery tests– performance tests

System Testing

• System Functional Test– Test entire system against the functional requirements.

• System Performance Test– Test the non-functional requirements of the system. For

example,– Response times, load testing etc.

• System Acceptance Test– Set of tests that the software must pass before it is

accepted by the client.

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Regression Testing

• Change do not always effect the entire program.

• Change in one part of system can effect other part.

• After each change– Entire test suite of a system must be run again.

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Need for an automatic test suite execution.

Test Activities

• Boils down to selecting and executing test cases. Test case consists of……– Set of test inputs, of if the program is non-

terminating, a sequence of test inputs.– Expected results when the inputs are executed;

and – Execution conditions or execution environment in

which the inputs are to be executed.

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These steps generally remain same from unit testing to system testing.

Test Case Selection

• Coverage criterion;– Equivalence Partitioning– Boundary-Value Analysis– Coverage-Based Testing

• Control-flow• Data-flow

• Expected behavior of every test input to be generated. (Test Oracles)

• Testing environment.

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Test Oracles

• Determines whether or not the program has passed or failed the test case.

• A test oracle is – A program– A process– A body of data

• In many cases - directly form the requirements. • For example, a test case assessing performance -

performance threshold.

24Difficult to automate or to assess their quality

Test Evaluation

• Compare the actual behavior with the expected behavior.

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Generally can be automated to an extend !!!!

Test Reporting

• Report the outcome of the testing.– Developers– Project Mangers etc.

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Generally can be automated to an extend !!!!

Testing Techniques

• White Box• Black Box• Incremental• Thread