Understanding Control Flow Testing | What Is Control Flow Testing ?

Introduction:

Control float checking out is a structural trying out strategy inside software program trying out, leveraging a application's manipulate glide as a version. It falls below the category of white field testing, requiring an information of the software program's structure, design, code, and implementation by the checking out crew. Developers frequently appoint this technique to evaluate their personal code, as they possess intimate expertise of the design and implementation info. The number one intention of control drift trying out is to validate the good judgment of the code, ensuring it aligns with user requirements. This method is particularly useful for examining both individual application segments and their interactions inside larger applications.

The Control flow testing is one of the types of software testing technique that is mainly related to the logical paths. It entails development of test cases which enshrine paths of the control flow graph of the particular software. Control flow testing is aimed at testing all the paths in the code that are possible to be taken, meaning that this kind of approach is used in order to increase the chance of finding defects that are associated with the program’s flow.

1. Control Flow Graph (CFG):

Chart that maps out all the possible paths that may be followed through the program every time the program is run.
Nodes are statements or instructions that are also called activities.
Edges show the control flow of a statement to another which defines the direction in a program.

2. Path Testing:

Choosing concrete branches out of the qualified control flow graph to guarantee the examination of each portion of the program.
Two types which are the basic paths and combination of basic paths.

3. Coverage Criteria:

Statement Coverage: Used to guarantee that every statement in the program is run in the least possible time.
Branch Coverage: Checks the flow with an emphasis on guaranteeing that each branch (decision point) is taken at least once.
Path Coverage: Implies that all the arcs of the program’s control flow graph have been traversed.

Control Flow Testing Process:

The manage float checking out method incorporates numerous key steps:

Create the Control Flow Graph:

Determine all the nodes and all the edges in the given program.
Draw out all the possible directions which might be followed in the program.

Determine the Test Paths:

Choose a number of paths that will exercise all the nodes and edges of the CFG of the control flow graph.
Ensure that you cover the program’s code with the maximum number of test cases with the least number of test cases.

Design Test Cases:

Practical test cases that would execute the chosen paths should be created.
Make sure that the test cases are sufficiently ‘heavy ‘ enough so that the flaws will be revealed.

Execute Test Cases:

Execute the test cases and consider the results got.
Subtotal the actual result values and the expected result values to reveal any differences.

Analyze Results:

Based on the results of the test cases, check for any defects.
Make any further changes you need to to the code and recreate the tests as needed.

Control Flow Graph:

A control float graph gives a graphical representation of the program's control waft or computation all through execution. Widely used in static analysis and compiler packages, manipulate waft graphs accurately depict the flow within a software unit. Frances E. Allen originally developed the concept of the manage flow graph.

A Control Flow Graph or CFG of a program represents all possible paths that the program may take during executing of the program. It has a benefit in the determination of the flow of control in the program and is important in types of testing like control flow testing.

This paper explores the following elements of a control flow graph:

Nodes: Serve to represent statements or instructions as a single entity in the program.
Edges: To show the transfer of control from one statement to another.
Entry Node: The program’s base and the main area of its activity.
Exit Node: The last point of a program.

Advantages of a Control flow graph :

Visualization: Useful in illustrating the sequence that control follows in a program.
Path Identification: Helps in finding out all the feasible directions across the program.
Testing: Aids in the development of test cases that targets different paths making the testing methods better.
Thus, the concept of the control flow graph will allow developers and testers deep and comprehensive analysis of the program’s logical structure and its successful testing, which will enhance the overall quality of the code and reliability of the software.

Cyclomatic Complexity:

Cyclomatic complexity serves as a quantitative measure of the variety of linearly impartial paths within a program. It is a essential software metric used to gauge application complexity and is computed the usage of the program's manage drift graph.

The formula for cyclomatic complexity is: M = E - N 2P

Objectives of Control Flow Testing:

Control drift checking out objectives to gain several goals:

Path Coverage: Ensuring that every viable course through the program is executed at the least once all through checking out.
Branch Coverage: Evaluating every decision factor (branch) inside the application as authentic or false in the course of trying out.
Decision Coverage: Verifying that each one ability results are protected by means of executing each decision point at the least once.
Loop Testing: Assessing the program's conduct in diverse loop eventualities, together with more than one, zero, and unmarried iterations.
Error-Handling Path Testing: Evaluating the program's mistakes and exception managing pathways.
Multiple Condition Testing: Testing both simple and complicated circumstance combos within decision points.
Boundary Value Examination: Assessing the software's conduct whilst input ranges are pushed to their limits.
Integration Testing: Examining interactions between distinctive software program modules or components.
Cyclomatic Complexity Reduction: Identifying and lowering the program's cyclomatic complexity.

Advantages and Disadvantages:

Advantages:

Detects almost half of the defects diagnosed at some stage in unit testing.
Identifies about one-0.33 of the defects within the whole software.
Can be accomplished manually or automated, permitting flexibility in control go with the flow graph introduction.
Increased Code Quality: As all paths are tested, control flow testing aids in detecting all the defects concerning the program’s control logic and structures.
Improved Test Coverage: Guarantees that all segment of the code is tested thus improving the chances of a code’s entire functionality being checked.
Detection of Logical Errors: Supports in discovering some sorts of mistakes that won’t be found by other testing approaches.

Disadvantages:

Difficulty in identifying lacking paths, specifically if the program and model are evolved by using the same person.
Unlikely to discover spurious features.
Complexity: As for large programs, determination of the control flow graph and its analysis may take as well as be Enormously time consuming.
Path Explosion: The number of possible paths can really expand from one room to the next, and it becomes very challenging to test each path in exhaustive detail and thus get to 100% path coverage.
Maintenance: One has to consider that updating the control flow graph with minor modifications in the code is likely to be a nuisance.

Example Program and Its Control Flow Graph:

void exampleFunction(int a, int b) {
    if (a > 0) {
        if (b > 0) {
            printf("a and b are positive.\n");
        } else {
            printf("a is positive, b is non-positive.\n");
        }
    } else {
        printf("a is non-positive.\n");
    }
}

Here's a diagram representing the control flow graph for the above program:

Node 1 (if a > 0): This is the recommended flow of the program; this is the first decision point in the program.

If the condition is true it goes to Node 2.
If the condition is false, gets to Node 5.

Node 2 (if b > 0): This is the second decision point of the program.

If condition is ‘true’, the control shifts to node 3.
If the condition is false then, the control moves to Node 4.

Node 3 (printf "a and b are positive. \n"): This is a statement node if condition A and condition B is true then a message is printed. It then goes to the Exit node where control is let to pass.
Node 4 (printf "a is positive, b is non-positive. \n"): It is a statement node that prints a message if the first condition is true but the second condition is false. Next the control is transferred to the Exit node.
Node 5 (printf "a is non-positive. \n"): This is a statement node where a message is printed if the condition; First condition is false. Then, control transits to the Exit node of the decision model.
Exit Node: The finality of the program is usually in this point.

Here's the reference video for you to watch and better understand the topic:

Conclusion :

Control flow testing is actually a very effective technique where the main check is on the logical flow of the program. This is basically due to the fact that when all its paths are tested systematically, it assists in identifying defects that may not be easily detected. Nonetheless, based on the analyses of the issues mentioned above, control flow testing is worthwhile to be implemented because of the advantages of amplifying code quality and carrying out comprehensive tests.

Control flow testing is a significant approach of software testing that majorly focuses on testing execution paths within the program. With the help of CFG, all the possible paths that the tested program can take are depicted, and the nodes represent single statements, while the edges are the transitions of control flow between the nodes. The advantage of this method is the same as in the previous one: the possibility of obtaining a dense coverage of paths, which means that all the possible program’s paths will be examined. Using Graphviz, PlantUML, JSON, and YAML as those instruments and formats helps in constructing and displaying CFGs which makes the application of CFT much more approachable and efficient. When control flow testing ideas are incorporated into a software development process, issues to do with logical and structural aspects of the code can be noted and corrected for, therefore improving the capacity and reliability of the software.