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Theory and Practice of Software Testing

Chapter 14 PresmanSoftware Testing Tactics

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Testing objectives [MYE79]

Testing is a process of executing a program with the goal of finding an error.

A good test is one that has a high probability of finding an error

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Good Testing

1. Has a high probability of finding an error

2. Is Not redudant3. Should be “best f breed”4. Should be neither too simple nor

too complex

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Testing Techniques Test information flow Test case design White box testing

Basis path testing Black box Testing

Equivalence Partitioning Boundary Value Analysis

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Test Information flow

testing

evaluation

Reliability model

debug

Software configuration

test configuration

testresults

errors

Error rate data

Expected results Predicted reliability

corrections

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Sometime called Glass-box testing A test case design philosophy that

uses the control program structure to derive test case

Knowledge of the program is used to identify additional test cases

White-Box testing

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White-Box testing

Objective is to exercise all program statements (not all path combinations) Every instruction Every decision

A set of paths that meets these criteria is said to provide cover or complete cover

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White-box testing

Componentcode

Testoutputs

Test data

DerivesTests

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Basis Path Testing One of white box testing technique The objective of basis path testing is to

derive a logical complexity measure of procedural design and defining a basis set of execution paths

Test case derived to exercise the basis set to execute every statement in the program at least one time during testing

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Basis Path testing Uses flow graph or program graph that

shows nodes representing program decisions and vertex representing the flow of control

Statements with conditions are therefore nodes in the flow graph Node is any point in the program where the

control either joins, or forks or both Nodes are joined by edges or links

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Contoh Program

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Predicate Node

Node that contain a conditiona Can be compound with logical

operator : “and” / “or”

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Independent Path (IP)

Independent Path is any path through the program that introduces at least one new set processing statement or a new condition

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A set of independent path

1-2-10-11-13 1-2-10-12-13 1-2-3-10-11-13 1-2-3-4-5-8-9-2-… 1-2-3-4-5-6-8-9-2-… 1-2-3-4-5-6-7-8-9-2…

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Process to deriving Test Cases

1. Map the design or code to the corresponding flow graph

2. Compute the cyclomatic complexity of the resultant flow graph

3. Identify a basis set of independent paths4. Prepare test cases that will force

execution of each path in the basis set

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Metric that provides a quantitative measure of logical complexity of a program

Define the number of independent path in the basis set of a program

The number of tests cases used to test all control statements equals the cyclomatic complexity

Cyclomatic Complexity : V(G)

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Compute Cyclomatic Complexity

1. V(G) = R2. V(G)= P +13. V(G) = E –N +2 Where :

R is the number of regions of the flow graph

P is the number of logical expressions (or predicates node)

E is the number of flow graph edges N is the number of flow graph nodes

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Path 1 test case

Specification of Inputs Value (k) = valid input, where k < i Value (i) = -999 where 2 i 100

Specification of Output (expected results): correct average based on k values and

correct totals should be computed Note:

This test case must be test as part of path 4, 5, and 6 tests

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Path 2 test case

Inputs Value (1) = -999

Expected results: Average = -999; other total at initial

values

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Path 3 test case

Inputs Attempt to process 101 or more

values The first 100 values should be valid

Expected results: correct average based on k values

and correct totals should be computed

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Path 4 test case

Inputs Value (i) = valid input, i < 100 Value (k) < minimum where k<i

Expected results: correct average based on k values

and correct totals should be computed

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Path 5 test case

Inputs Value (i) = valid input where i< 100 Value (i)> maximum where k i

Expected results: correct average based on n values

and correct totals should be computed

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Path 6 test case

Inputs Value (i) = valid input where i< 100

Expected results: correct average based on n values

and correct totals should be computed

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Main tactics on path selection

A sufficient number of paths to achieve coverage

Selection of short, functionally sensible paths

Minimizing the number of changes from path to path (one decision changing at a time)

Favor more but simpler paths over fewer but complicated paths

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Effectiveness path testing

Approximately between 60-70% of all bugs can be caught in unit testing using basis path testing

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Main Limitations of Basis path testing

Can not be used to show totally wrong or missing functions

Interface errors may not be caught Database errors may not be caught Not all initialization errors are caught by

path testing

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Graph Metrices

A tabular representation of flow graph with link weight addition to provide information about control flow

A square matrix whose size ( row & column) is equal to the number of node on flow graph

Existing connection ( 1 & 0)

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Link Weight

Probability an edge will be executed

Processing time expended, Memory required, Resources required,during traversal of a link

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Control Structure Testing

1. Condition Testing a test case design method that exercise the logical conditions contained in a program module

2. Data Flow Testinga method to select a test path of a program according to the location of definitions and uses of variable in the program

3. Loop Testinga white box testing technique that focuses exclusively on the validity of loop construct

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Loop Testing

4 different classes of loop : Simple loop Nested loop Concatenated loop Unstructured loop

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Simple Loop test criteriaThe following set of test can be applied to a

simple loop of size max1. Skip the loop entirely2. One pass through the loop3. Two passes through the loop before existing4. M passes through the loop where M < max5. max-1, max, max+1 passes through the loop

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Nested Loop test criteria

1. Start at the inner loop. Set all other loop to a minimum value

2. Conduct simple loop testing for the innermost loop

3. Work outward, repeat for all loops. Keeping all other outer loops at minimum value & other nested loops to “typical value”

4. Continue until all loops tested

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Concatenated Loops

If independent loops, use simple loop testing

If dependent, treat as nested loops

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Unstructured Loops

Don’t test - redesign