Software Testing

Software Testing
Inam Ul Haq
OOA/D, BSIT
Inam.bth@gmail.com
Guest Lecture
OOA/D, BSIT-5th, Univesity of
Education Okara
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Observations about Testing
 “Testing is the process of executing a
program with the intention of finding
errors.” – Myers
 “Testing can show the presence of bugs
but never their absence.” - Dijkstra
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Good Testing Practices
 A good test case is one that has a high
probability of detecting an undiscovered
defect, not one that shows that the
program works correctly
 It is impossible to test your own program
 A necessary part of every test case is a
description of the expected result
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Good Testing Practices (cont’d)
 Avoid nonreproducible or on-the-fly testing
 Write test cases for valid as well as invalid input
conditions.
 Thoroughly inspect the results of each test case
 As the number of detected defects in a piece of
software increases, the probability of the
existence of more undetected defects also
increases
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Good Testing Practices (cont’d)
 Assign your best people to testing
 Ensure that testability is a key objective
in your software design
 Never alter the program to make testing
easier
 Testing, like almost every other activity,
must start with objectives
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Levels of Testing
 Unit Testing
 Integration Testing
 Validation Testing
 Regression Testing
 Alpha Testing
 Beta Testing
 Acceptance Testing
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Unit Testing
 Algorithms and logic
 Data structures (global and local)
 Interfaces
 Independent paths
 Boundary conditions
 Error handling
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Why Integration Testing Is Necessary
 One module can have an adverse effect
on another
 Subfunctions, when combined, may not
produce the desired major function
 Individually acceptable imprecision in
calculations may be magnified to
unacceptable levels
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Why Integration Testing Is Necessary (cont’d)
 Interfacing errors not detected in unit
testing may appear
 Timing problems (in real-time systems)
are not detectable by unit testing
 Resource contention problems are not
detectable by unit testing
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9

Validation Testing
 Determine if the software meets all of the
requirements defined in the SRS
 Having written requirements is essential
 Regression testing is performed to determine if
the software still meets all of its requirements in
light of changes and modifications to the
software
 Regression testing involves selectively
repeating existing validation tests, not
developing new tests
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Alpha and Beta Testing
 It’s best to provide customers with an
outline of the things that you would like
them to focus on and specific test
scenarios for them to execute.
 Provide with customers who are actively
involved with a commitment to fix defects
that they discover.
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Acceptance Testing
 Similar to validation testing except that
customers are present or directly
involved.
 Usually the tests are developed by the
customer
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Test Methods
 White box or glass box testing
 Black box testing
 Top-down and bottom-up for performing
incremental integration
 ALAC (Act-like-a-customer)
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Test Types
 Functional tests
 Algorithmic tests
 Positive tests
 Negative tests
 Usability tests
 Boundary tests
 Startup/shutdown tests
 Platform tests
 Load/stress tests
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Test Planning
 The Test Plan – defines the scope of the
work to be performed
 The Test Procedure – a container
document that holds all of the individual
tests (test scripts) that are to be
executed
 The Test Report – documents what
occurred when the test scripts were run
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Test Plan
 Questions to be answered:
 How many tests are needed?
 How long will it take to develop those tests?
 How long will it take to execute those tests?
 Topics to be addressed:
 Test estimation
 Test development and informal validation
 Validation readiness review and formal validation
 Test completion criteria
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Entrance Criteria for Formal
Validation Testing
 Software development is completed (a
precise definition of “completed” is required.
 The test plan has been reviewed, approved
and is under document control.
 A requirements inspection has been
performed on the SRS.
 Design inspections have been performed on
the SDDs (Software Design Descriptions).
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Validation Testing (cont’d)
 Code inspections have been performed on all
“critical modules”.
 All test scripts are completed and the
software validation test procedure document
has been reviewed, approved, and placed
under document control.
 Selected test scripts have been reviewed,
approved and placed under document
control.
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Validation Testing (cont’d)
 All test scripts have been executed at least
once.
 CM tools are in place and all source code is
under configuration control.
 Software problem reporting procedures are in
place.
 Validation testing completion criteria have
been developed, reviewed, and approved.
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Exit Criteria for Validation
Testing
 All test scripts have been executed.
 All SPRs have been satisfactorily resolved.
(Resolution could include bugs being fixed,
deferred to a later release, determined not to
be bugs, etc.) All parties must agree to the
resolution. This criterion could be further
defined to state that all high-priority bugs
must be fixed while lower-priority bugs can be
handled on a case-by-case basis.
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Exit Criteria for Validation
Testing (cont’d)
 All changes made as a result of SPRs have
been tested.
 All documentation associated with the
software (such as SRS, SDD, test
documents) have been updated to reflect
changes made during validation testing.
 The test report has been reviewed and
approved.
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Test Estimation
 Number of test cases required is based on:
 Testing all functions and features in the SRS
 Including an appropriate number of ALAC (Act
Like A Customer) tests including:
 Do it wrong
 Use wrong or illegal combination of inputs
 Don’t do enough
 Do nothing
 Do too much
 Achieving some test coverage goal
 Achieving a software reliability goal
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Considerations in
Test Estimation
 Test Complexity – It is better to have many
small tests than few large tests.
 Different Platforms – Does testing need to be
modified for different platforms, operating
systems, etc.
 Automated or Manual Tests – Will automated
tests be developed? Automated tests take more
time to create but do not require human
intervention to run.
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Estimating Tests Required
SRS
Reference
Estimated
Number of
Tests
Required
Notes
4.1.1 3 2 positive and 1 negative test
4.1.2 2 2 automated tests
4.1.3 4 4 manual tests
4.1.4 5 1 boundary condition, 2 error
conditions, 2 usability tests
…
Total 165
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Estimated Test Development
Time
Estimated Number of Tests: 165
Average Test Development Time: 3.5
(person-hours/test)
Estimated Test Development Time:
577.5
(person-hours)
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Estimated Test Execution
Time
Estimated Number of Tests: 165
Average Test Execution Time: 1.5
(person-hours/test)
Estimated Test Execution Time: 247.5
(person-hours)
Estimated Regression Testing (50%): 123.75
(person-hours)
Total Estimated Test Execution Time: 371.25
(person-hours)
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Test Procedure
 Collection of test scripts
 An integral part of each test script is the
expected results
 The Test Procedure document should
contain an unexecuted, clean copy of
every test so that the tests may be more
easily reused
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Test Report
 Completed copy of each test script with evidence
that it was executed (i.e., dated with the
signature of the person who ran the test)
 Copy of each SPR showing resolution
 List of open or unresolved SPRs
 Identification of SPRs found in each baseline
along with total number of SPRs in each baseline
 Regression tests executed for each software
baseline
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Validation Test Plan
IEEE – Standard 1012-1998
1. Overview
a. Organization
b. Tasks and Schedules
c. Responsibilities
d. Tools, Techniques, Methods
2. Processes
a. Management
b. Acquisition
c. Supply
d. Development
e. Operation
f. Maintenance
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Validation Test Plan
IEEE – Standard 1012-1998 (cont’d)
3. Reporting Requirements
4. Administrative Requirements
5. Documentation Requirements
6. Resource Requirements
7. Completion Criteria
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Practical Web Testing
 Capture whole page including web address
 Write briefly and clearly
 Point only main issues (bugs)
 Point one screen shot per issue
 Make final reporting document for bugs
 http://jmp.sh/meF4kMP check test case demo
and make your own, choose a topic and go.
 Non-graded assignment, make, save and share on
official Facebook page and ComputingForum
Education Okara
31

Software Testing

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