Software Testing Fundamentals

Fundamentals of Software Testing

• Software Testing is evaluating a system or component through manual or automated methods.
• The goal is to verify that the system meets specified requirements.
• It also identifies differences between expected and actual results.

Errors, Faults, and Failures

• An Error occurs during the process of writing a program.
• A fault is a manifestation of one or more errors, also known as a bug or defect.
• A failure occurs when faulty code is executed during operation.

Testing Principles

• Testing should start during the requirements phase.
• Program testing can reveal the presence of errors but never prove their absence.
• The programmer should not be the tester.
• A test cycle is guided by a test plan.

Professional Testers

• Developers often cannot find their own defects due to lack of motivation, skills, or time.
• Testers aim to find errors, faults, and failures, and work with developers to fix them.
• Testers can assess software from a customer's or user's perspective.
• Testers possess specific skills, tools, and experience.

Levels/Phases of testing during Development

• Testing types are: Unit, Integration, Component, System, User Acceptance and Regression.

User-Based Testing

• Alpha testing occurs with actual end-users within the development environment.
• Beta testing occurs with end-users in their environment before a general release.
• Acceptance testing is formal testing to allow customers to determine whether to accept the system, this can be defined within a contract.

Other Types of Testing

• Regression testing detects problems in code caused by program changes.

Test Oracle & Test Bed

• A test oracle is a document or software to allow testers to determine whether a test passed or failed.
• A test bed is an environment with all the hardware/software to test a software component or system.
• The test bed includes simulators, emulators, memory checkers, hardware probes, and test tools.

Static Testing

• Static testing involves evaluating software without executing code.
• Reviews are used to find and eliminate errors or ambiguities in design, requirement, and test case documents.
• Reviews include walkthroughs and inspections.
• Static analysis uses tools to analyze code for structural defects that could lead to defects.

Test Cases

• In Test case data, a single test case includes both test data and the predicted output.
• Test cases should cover both valid/expected and invalid/unexpected input conditions.
• A test set is a collection of zero or more test cases.
• As an example of sorting, if the test data were "A 12 -29 32", the expected output is "-29 12 32".
• A test case includes: Test inputs, conditions, expected outputs, and related test procedures.

Sample Test Case

• The Actual output gets compared to the expected output.
• If the actual result matches the Expected Result: PASS.
• If the actual result is different to the Expected Result: FAIL.

Nature of Test Cases

• Each test should verify that a requirement is satisfied.
• Tests generate a minimum number of test cases to find the most amount of errors.
• A good test case has a high probability of finding any undiscovered error.
• Test cases should not be redundant.
• Select test cases that could cover various error types.

Self-Assessment Test

• A demonstration of a program reading three integers that makes up the sides of a triangle.
• The program needs to establish whether the triangle is: scalene, isosceles, equilateral, impossible, or "not a triangle".

Requirements Assessment

• Requirements should lead to two different programs:
• Requirement 1 should input two integers and output the maximum of them.
• Requirement 2 should input a sequence of integers and output them in sorted order.

Input Domain/Space

• The input domain or input space of P is the set of all possible inputs to a program P.
• For requirement 1, the input domain has pairs of integers in the range of -32,768 to 32,767.
• For requirement 2, it's not possible to find the input domain for the sort program.

Modified Input Domain

• Modified program should input a sequence of integers and output them sorted in ascending or descending order.
• An A is required for ascending order and a D is required for descending order.