A control flow graph (CFG) is a representation, using graph theory, of all paths that might be traversed through a program during its execution. It is used in white-box testing to ensure that all parts of the code are tested.
To use a CFG for white-box testing, follow these steps:
Construct the CFG: Identify all the decision points in your code (like if-else statements, loops, switch cases, etc.) and construct a graph where each node represents a line of code or a block of code, and edges represent the flow of execution between these blocks.
Identify Paths: Determine all possible paths through the CFG. A path is a sequence of nodes (code blocks) from the start node to the end node, following the edges that represent execution flow.
Design Test Cases: For each path identified, design a test case that will traverse that path. This means providing inputs to the program that will cause the execution to follow that specific path.
Execute Test Cases: Run the designed test cases against the program to ensure that all paths behave as expected.
Analyze Results: Check the results of each test case to ensure that the program behaves correctly on all identified paths.
Example: Consider a simple program fragment with an if-else statement:
if x > 0:
print("Positive")
else:
print("Non-positive")
The CFG for this fragment would have two nodes representing the if and else blocks and edges connecting them based on the condition x > 0.
Test cases would be designed to cover both paths:
x = 1 should print "Positive".x = -1 should print "Non-positive".Cloud Service Recommendation: When dealing with large and complex systems, manually creating and maintaining CFGs can be challenging. Tencent Cloud's Cloud Studio provides a powerful development environment with integrated tools that can assist in code analysis, including the generation and visualization of control flow graphs, making white-box testing more efficient.