📘 TESTING TECHNIQUES (Software Testing & QA)

✅ 1. What are Testing Techniques?

Definition: Testing techniques are methods used to design test cases that help find defects (bugs) in software effectively.

👉 In simple words: They tell us how to test a program properly.

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🎯 Why are Testing Techniques Important?

• Help find maximum bugs with minimum effort
• Ensure complete test coverage
• Improve software quality
• Save time and cost

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🔑 TYPES OF TESTING TECHNIQUES

Testing techniques are mainly divided into:

                 Testing Techniques
                        |
        ---------------------------------
        |               |               |
   Black Box      White Box       Grey Box
   Testing        Testing         Testing

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🟢 2. BLACK BOX TESTING (Functional Testing)

📌 Definition:

Black box testing is a technique where the tester does NOT know the internal code and tests only based on inputs and outputs.

👉 Focus: What the system does

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🔍 Key Idea:

• No knowledge of code
• Based on requirements/specifications

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🧪 Common Black Box Techniques

1. Equivalence Partitioning (EP)

📌 Definition:

Divides input data into valid and invalid groups (partitions).

🪜 Steps:

1. Identify input field
2. Divide into valid/invalid ranges
3. Select one value from each group

📊 Example:

Age field (valid: 18–60)

Partition	Type	Example
<18	Invalid	15
18–60	Valid	25
>60	Invalid	70

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2. Boundary Value Analysis (BVA)

📌 Definition:

Tests values at the edges (boundaries) of input ranges.

🪜 Steps:

1. Identify limits

2. Test:

   • Minimum
   • Minimum+1
   • Maximum-1
   • Maximum

📊 Example:

Range: 1–100 Test values: 0, 1, 2, 99, 100, 101

👉 🔥 Frequently Asked!

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3. Decision Table Testing

📌 Definition:

Used when output depends on multiple conditions.

📊 Example:

Condition	Rule 1	Rule 2
Valid login	Yes	No
Correct password	Yes	Yes
Output	Login success	Error

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4. State Transition Testing

📌 Definition:

Used when system behavior depends on states.

📊 Example:

ATM machine states:

Idle → Card Inserted → PIN Entered → Transaction → Exit

👉 Tests valid & invalid transitions.

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5. Use Case Testing

• Based on real user scenarios
• Tests complete workflows

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⭐ Advantages:

• No programming knowledge required
• User-focused testing

❌ Disadvantages:

• Cannot test internal logic
• Limited coverage

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🔵 3. WHITE BOX TESTING (Structural Testing)

📌 Definition:

Testing technique where the tester knows internal code/logic.

👉 Focus: How the system works

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🔍 Key Idea:

• Tests code structure
• Requires programming knowledge

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🧪 Common White Box Techniques

1. Statement Coverage

📌 Definition:

Ensure every line of code executes at least once

📊 Example:

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

👉 Test case must execute this line.

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2. Branch Coverage

📌 Definition:

Ensure each decision branch (true/false) is tested

📊 Example:

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

👉 Test both:

• x > 0
• x ≤ 0

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3. Path Coverage

📌 Definition:

Test all possible execution paths

👉 🔥 Very important for exams!

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4. Loop Testing

📌 Definition:

Test loops with:

• 0 iterations
• 1 iteration
• Many iterations

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5. Data Flow Testing

📌 Definition:

Focus on variables (data usage)

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⭐ Advantages:

• Finds hidden bugs
• Improves code quality

❌ Disadvantages:

• Requires coding knowledge
• Time-consuming

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🟡 4. GREY BOX TESTING

📌 Definition:

Combination of Black Box + White Box

👉 Tester has partial knowledge of code

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🔍 Key Idea:

• Tests both:

  • Functional behavior
  • Internal structure (limited)

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📊 Example:

• Testing a login system:

  • Input: username/password (black box)
  • Also checks database queries (white box)

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⭐ Advantages:

• Better coverage
• More effective than black box

❌ Disadvantages:

• Requires some technical knowledge

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📊 DIAGRAM: COMPARISON OVERVIEW

Black Box → No code knowledge → Input/Output testing
White Box → Full code knowledge → Logic testing
Grey Box  → Partial knowledge → Combined testing

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🔥 FREQUENTLY ASKED EXAM POINTS

✔ Definition of each technique ✔ Difference between Black Box & White Box ✔ Equivalence Partitioning vs Boundary Value Analysis ✔ Statement vs Branch Coverage ✔ Advantages & disadvantages ✔ Examples of each technique

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🧠 QUICK REVISION TABLE

Feature	Black Box Testing	White Box Testing	Grey Box Testing
Knowledge of Code	❌ No	✅ Yes	⚠️ Partial
Focus	Functionality	Code logic	Both
Based On	Requirements	Code structure	Design + Code
Performed By	Testers	Developers	Testers/Developers
Techniques	EP, BVA, Decision Table	Statement, Branch, Path	Combination
Advantage	Easy to perform	Deep testing	Balanced approach
Disadvantage	Limited coverage	Complex	Requires skill

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🎯 FINAL SUMMARY

• Testing techniques are methods to design test cases.

• There are 3 main types:

  • Black Box → test functionality
  • White Box → test internal logic
  • Grey Box → combination

• Important techniques:

  • EP & BVA (very common in exams)
  • Statement & Branch coverage

• Each technique has its own purpose and benefits

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