1. Neringa Sipavičienė IFM-2/4
Software testability
Neringa Sipavičienė IFM-2/4
The time you save in testing is the time you gain for testing.

2. What is testability?
Testability - The capability of the software product to enable modified software to be tested. [ISO 9126].
Software testability is the degree to which a software artifact (i.e. a software system, software module, requirements or design document) supports testing in a given test context.
SOFTWARE TESTABILITY is an external attribute of the software that evaluates the complexity and the effort required for software testing.
Software testability

3. Abstract
A software component's testability or application's testability is regarded as a measure of the difficulty incurred when testing a component or application.
If testing is considered as not being difficult, then the testability of the software is considered as being high.
If testing is considered as being a difficult process to perform, testability is considered as being lower.
The reason for seeking testability ratings is to determine early in the software development life cycle how many testing resources will be needed in order to complete the testing process.
Software testability

4. Software Testability
Software testability is a key aspect to allow the detection of difficult to uncover defects in software. Software testability supports the testing process and facilitates the creation of better quality software.
Testing and testability are complimentary: testing can reveal faults (testability cannot) but testability can suggest locations where faults can hide from testing (something testing cannot do alone).
Software testability must be designed into the software as it is developed. Therefore, it is an attribute of the software that requires close development cooperation with test.
Software testability

5. Heuristics of software testability
Controllability - The better we can control it, the more the testing can be automated and optimized.
Visibility - What you see is what can be tested.
Availability - To test it, we have to get at it.
Simplicity - The simpler it is, the less there is to test.
Stability - The fewer the changes, the fewer the disruptions to testing.
Information - The more information we have, the smarter we will test.
James Bach
Software testability

6. Testability of Requirements
Requirements need to fulfill the following criteria in order to be testable:
Consistent;
Complete;
Unambiguous;
Quantitative (a requirement like "fast response time" can not be verified);
Verifiable in practice (a test is feasible not only in theory but also in practice with limited resources).
Software testability

7. Testability myths Myth: Testability is expensive.
Testability doesn't have to be expensive. A small investment throughout the project phase can give us a major improvement in fault detection.
Myth: Testability can be a plug-in.
Testability is a way of ensuring quality. Just like quality cannot be added in a product as a separate ingredient, testability follows the same trend. It has to be gradually built into the product over time.
Myth: Low budget applications cannot afford testability.
Low budget applications will normally have large volumes of sales with large number of user licenses. This will increase the cost of maintenance if the application is not maintainable. Thus a modest investment right at the start can save a lot of hassles and maintenance costs after the sale and implementation of the software.
Software testability

8. Questions What is testability? Why is software testability important?
Name 3 heuristics of software testability?
What criteria requirements need to fullfil in order to be testable?
What are testability myths?
Software testability

9. Thank you!
Software testability

10. references ISTQB Glossary
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Software testability