Control Flow Testing


Control Flow Testing in SDLC

In this article, I am going to discuss Control Flow Testing in SDLC. Please read our previous article where we discussed Data Flow Testing. At the end of this article, you will understand the following important pointers which are related to Control Flow Testing in SDLC.

  1. What is Control Flow Testing in SDLC?
  2. What is the use of Control Flow Testing?
  3. Different Stages in Control Flow Testing in SDLC
  4. Control Flow Testing Notation
  5. What are the Advantages of Control Flow Testing?
  6. What are the Disadvantages of Control Flow Testing?
What is Control Flow Testing in SDLC?

Software testing methodology known as “Control Flow Testing” aims to verify the accuracy and efficiency of a program’s control flow. The sequence and order in which the program’s statements and instructions are carried out during runtime is referred to as the control flow. Control flow testing’s goal is to make sure that all potential program pathways, branches, and decisions are tested in order to find any potential flaws or problems. It seeks to test various control structures, including conditionals, branches, and loops, to see if the program acts as predicted under various circumstances. Since developers have a better understanding of the design, code, and implementation, they frequently utilize this type of testing technique to check their own implementation and code. The goal of this testing strategy is to validate the code’s logic and ensure that it satisfies user expectations. Its primary use is for connecting smaller programs and parts of larger programs.

What is the use of Control Flow Testing?

Software testing methodology known as “control flow testing” focuses on evaluating the accuracy and efficiency of the control flow within a program. Making sure that all potential paths and decision points inside a program are run and assessed, entails building test cases. Control flow testing has several important applications, such as:

  1. Measurement of Coverage: Control flow testing aids in determining how well test cases cover a program’s control flow. It guarantees that during testing, all control statements—including loops, conditionals, and branches—are used. Developers and testers can evaluate the thoroughness of their testing efforts by assessing the coverage.
  2. Error Detection: Control flow testing seeks to find mistakes, problems, and defects associated with a program’s control flow. It increases the likelihood of finding problems such as erroneous branching, dead code, infinite loops, and inaccessible code parts by traversing several control routes. This enhances the software’s overall resilience and dependability.
  3. Path Validation: Control flow testing confirms that each conceivable path inside a program has been run and assessed. This process is known as path validation. It guarantees that the desired behavior is produced in a variety of circumstances. It assists in identifying situations when the program might act unexpectedly or create inaccurate results by exercising several control routes.
  4. Decision Coverage: High decision coverage is a goal for control flow testing that entails exercising both the true and false branches of conditional statements. Control flow testing aids in finding problems linked to improper conditions, missing or redundant branches, and undesired control flow behavior by developing test cases that cover all potential decision possibilities.
  5. Test Suite creation: The creation of thorough test suites is aided by control flow testing. It assists testers in locating key routes, prioritizing the execution of test cases, and identifying the bare minimum number of test cases necessary to reach specified coverage levels. A program’s control flow can be taken into account by testers to help them design test suites that maximize the chance of identifying bugs.
  6. Integration Testing: Control flow testing is useful during the integration testing stage when several components or modules are brought together. It checks the proper operation of control flows and interactions between various program components. Control flow testing aids in locating integration problems and dependencies by testing various control paths and assessing how the integrated system behaves.
Different Stages in Control Flow Testing in SDLC

The steps in the control flow testing procedure are as follows:


Different Stages in Control Flow Testing in SDLC

  1. Control Flow Graph Creation: From the provided source code, we can manually draw the graph or use tools to do so.
  2. Coverage Target: Over the control flow graph, which consists of nodes, edges, pathways, branching, etc., a coverage target is defined.
  3. Test Case Creation: Control flow diagrams are used to build test cases that cover the specified coverage target.
  4. Test Case Execution: Additional test cases are run after the generation of test cases that cover the coverage target.
  5. Analysis of Results: Determine whether the program is error-free or whether it has certain flaws by analyzing the outcome.
Control Flow Testing Notation

To specify every conceivable execution path, a control flow graph is constructed using nodes, edges, junction nodes, and decision nodes. For control flow testing, four nodes are utilized. As follows:


Nodes in the control flow graph are crucial for building a path of procedures. The order of the operations or statements, as well as their succession, are represented by the nodes. With the assistance of the testing team, it is possible to determine the order of the instructions. The nodes in the control flow graph stand in for the collection of program statements. In a graph, there are entry and exit nodes, which are two of the five main types of nodes. This is a diagram of a control flow graph.

Control Flow Testing Notation

We can observe that the graph’s entry node or starting node is shown in this diagram. Following the assignment of the nth value, the decision node will be tasked with determining whether or not the value of n is higher than or less than 21. The procedure will execute as eligible if the value of n is higher than or equal to 21, and as not eligible if the value of n is less than 21. The process will finally come to a close at the junction node, which is the last node.


A direction arrow indicating which nodes are related to which other nodes is called an edge in a control flow graph. The edge is in charge of joining the starting node with the ending node. It is clear from the following diagram where and in which direction the arrows are leading as they connect the nodes.

Decision Node:

The control flow graph’s decision node is one of the most significant types of node because it shows which node the process will go to next based on conditional values. It is a conditional statement that generates two or more switch or if statements, among other types of control statements. In the aforementioned illustration, the decision node handles the process that will proceed next based on the value of n. The eligible process will run if the value of n is higher than or equal to 21, otherwise, if the value is less than 21, the non-eligible process will run.

Junction Node:

A junction node in a control flow graph is where at least three nodes come together.

What are the Advantages of Control Flow Testing?

Control flow testing, a potent method used in software testing, makes sure that all feasible program routes are carried out and assessed. These are its main benefits, in brief:

  1. Coverage that is thorough: Control flow testing seeks to put every branch and decision point in the code to the test, increasing the likelihood of finding bugs.
  2. Error detection: Control flow testing exposes potential mistakes, such as improper conditions, missing or redundant code, and unexpected behaviors, by methodically navigating various control paths.
  3. Test case optimization aids in locating duplicate or pointless test cases, hence lowering total testing costs without sacrificing test coverage.
  4. Early bug discovery: Control flow testing can identify problems early in the development cycle, allowing for prompt bug correction and averting more serious difficulties later.
  5. Raised possibility of delivering a higher-quality software product: By thoroughly testing a program’s control flow, the likelihood of dependability and user satisfaction are raised.
What are the Disadvantages of Control Flow Testing?

Although effective in some circumstances, control flow testing has a number of drawbacks that must be taken into account.

  1. Control flow testing may not cover all feasible paths and combinations inside a program, which could result in errors that go unnoticed.
  2. Time-consuming: Control flow tests’ design and execution might take a while, especially for complicated systems with plenty of conditional statements and loops.
  3. Limited Fault Detection: Control flow testing frequently ignores particular input values or external dependencies that can influence program behavior in favor of concentrating largely on the structure of the code.
  4. Lack of Real-world settings: Control flow testing may not accurately mimic real-world settings, which makes it challenging to spot defects that result from intricate interactions between many systems or components.
  5. Control flow tests can become out-of-date and require frequent revisions as the code evolves, which makes them expensive to maintain.

In the next article, I am going to discuss Branch Coverage Testing. Here, in this article, I try to explain Control Flow Testing in SDLC. I hope you enjoy this SDLC Control Flow Testing article.


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