White-box testing techniques in Software Engineering - Step-by-Step Execution

Concept Flow - White-box testing techniques

Start: Understand Code

↓

Select Technique

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Statement

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Execute

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Find Bugs

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Fix Code

White-box testing starts by understanding the code, then choosing techniques like statement, branch, or path testing to check code parts and find bugs.

Execution Sample

Software Engineering

if (x > 0) {
  y = 1;
} else {
  y = -1;
}

This code checks if x is positive and assigns y accordingly; white-box testing will check both branches.

Analysis Table

Step	Condition (x > 0)	Branch Taken	Action	Output
1	x = 5 > 0	True branch	y = 1	y = 1
2	x = -3 > 0	False branch	y = -1	y = -1
3	x = 0 > 0	False branch	y = -1	y = -1
4	All branches tested?	Yes	Testing complete	No bugs found or bugs identified

💡 All branches have been tested to ensure code behaves correctly in each case.

State Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
x	undefined	5	-3	0	varies per test
y	undefined	1	-1	-1	depends on x

Key Insights - 3 Insights

Why do we need to test both true and false branches?

Because each branch can behave differently, testing both ensures no hidden bugs in either path, as shown in execution_table steps 1 and 2.

What if a path is very long or complex?

Path testing tries to cover all possible paths, but for complex code, testers focus on important or risky paths to manage effort, as full path coverage can be impractical.

Is statement testing enough to find all bugs?

No, statement testing checks if each line runs but may miss bugs in decision logic; branch testing adds checking all decision outcomes, improving coverage.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of y after step 2?

A 1

B -1

C 0

D undefined

💡 Hint

Check the 'Output' column in row for step 2 in execution_table.

At which step does the condition x > 0 evaluate to false for the first time?

A Step 2

B Step 1

C Step 3

D Step 4

💡 Hint

Look at the 'Condition (x > 0)' column in execution_table rows.

If we only test the true branch, what is missing according to the execution_table?

A Testing all statements

B Testing variable initialization

C Testing false branch and possible bugs there

D Testing output formatting

💡 Hint

Refer to the 'Branch Taken' column and see which branch is not tested if only true branch is checked.

Concept Snapshot

White-box testing techniques:
- Statement testing: run every line
- Branch testing: test each decision outcome
- Path testing: cover all possible paths
Goal: find bugs by checking internal code logic
Requires code knowledge and careful test design

Full Transcript

White-box testing techniques involve understanding the internal code and testing it thoroughly. The main methods include statement testing, which ensures every line of code runs; branch testing, which checks every decision's true and false outcomes; and path testing, which tries to cover all possible routes through the code. For example, a simple if-else statement is tested by running cases where the condition is true and false. This helps find bugs that might only appear in certain branches. Testing all branches is important because each can behave differently. Path testing can be complex for large code, so testers focus on critical paths. Statement testing alone may miss bugs in decision logic, so branch testing improves coverage. By following these techniques, testers can find and fix bugs early, improving software quality.