📘 WHITE BOX TESTING TECHNIQUES

✅ 1. What is White Box Testing?

Definition: White Box Testing is a technique where the tester has full knowledge of the internal code, structure, and logic of the program.

👉 Simple meaning: You test how the program works internally (code logic).

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🎯 Key Features

• Requires programming knowledge

• Tests internal structure

• Also called:

  • Structural Testing
  • Glass Box Testing
  • Clear Box Testing

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📦 Basic Working

Input → Code Logic → Output
         ↑
     Tested here

👉 Focus is on code execution paths

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🔑 MAIN WHITE BOX TESTING TECHNIQUES

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🔵 1. STATEMENT COVERAGE

📌 Definition:

Ensures that every line (statement) of code is executed at least once.

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🪜 Steps:

1. Identify all statements in code
2. Design test cases to execute each statement
3. Measure coverage

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📊 Example:

if (x > 0)
   print("Positive");

👉 Test case:

• x = 5 → executes the statement

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📐 Formula:

Statement Coverage = (Executed Statements / Total Statements) × 100%

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🎯 Key Point:

• Minimum level of testing
• Does NOT guarantee full logic testing

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🟢 2. BRANCH COVERAGE (Decision Coverage)

📌 Definition:

Ensures that each decision (true/false branch) is executed.

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📊 Example:

if (x > 0)
   print("Positive");
else
   print("Negative");

👉 Test cases:

• x = 5 → TRUE branch
• x = -2 → FALSE branch

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📐 Formula:

Branch Coverage = (Executed Branches / Total Branches) × 100%

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🎯 Key Point:

• More powerful than statement coverage
• Covers all decision outcomes

👉 🔥 Frequently asked!

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🟡 3. PATH COVERAGE

📌 Definition:

Ensures that all possible execution paths in the program are tested.

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📊 Example:

if (x > 0)
   print("Positive");
if (y > 0)
   print("Y Positive");

👉 Possible paths:

1. x>0, y>0
2. x>0, y≤0
3. x≤0, y>0
4. x≤0, y≤0

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🎯 Key Point:

• Provides maximum coverage
• Difficult for large programs

👉 🔥 Very important for exams!

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🟣 4. LOOP TESTING

📌 Definition:

Tests the correctness of loops (for, while, do-while).

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🪜 Test Cases for Loop:

• 0 iterations
• 1 iteration
• 2 iterations
• Maximum iterations

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📊 Example:

for(i=0; i<n; i++)
   print(i);

👉 Test with:

• n = 0
• n = 1
• n = many

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🎯 Key Point:

• Helps detect infinite loops
• Ensures loop correctness

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🟠 5. DATA FLOW TESTING

📌 Definition:

Focuses on how variables are defined, used, and modified in the program.

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🔍 Key Concepts:

• Definition (value assigned)
• Use (value used)
• Kill (value removed)

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📊 Example:

int x = 5;   // define
print(x);    // use

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🎯 Key Point:

• Finds errors like:

  • Unused variables
  • Undefined variables

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🔴 6. CONDITION COVERAGE

📌 Definition:

Tests each individual condition in a decision.

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📊 Example:

if (x > 0 && y > 0)

👉 Conditions:

• x > 0
• y > 0

Test cases:

• Both true
• One false
• Both false

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🎯 Key Point:

• More detailed than branch coverage

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🧠 COVERAGE HIERARCHY (Important!)

Statement < Branch < Condition < Path

👉 Path coverage is strongest.

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⚖️ ADVANTAGES & DISADVANTAGES

✅ Advantages:

• Finds hidden errors
• Improves code quality
• Ensures logic correctness

❌ Disadvantages:

• Requires programming knowledge
• Time-consuming
• Not suitable for large systems fully

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🔥 FREQUENTLY ASKED EXAM POINTS

✔ Define White Box Testing ✔ Statement vs Branch Coverage ✔ Path Coverage explanation ✔ Loop testing cases ✔ Coverage formulas ✔ Coverage hierarchy

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📊 QUICK REVISION TABLE

Technique	What it Tests	Key Idea
Statement Coverage	All lines	Each statement executed
Branch Coverage	Decisions	True/False paths
Path Coverage	All paths	Complete execution
Loop Testing	Loops	Iterations
Data Flow Testing	Variables	Define & use
Condition Coverage	Conditions	Each condition

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🎯 FINAL SUMMARY

• White Box Testing focuses on internal code logic

• Requires programming knowledge

• Key techniques:

  • Statement Coverage
  • Branch Coverage
  • Path Coverage
  • Loop Testing
  • Data Flow Testing
  • Condition Coverage

• Branch & Path coverage are most important for exams

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