5 - Test Case Design Techniques

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Understanding Test Scenarios and Test Cases

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Teacher
Teacher

Today, we're focusing on the differences between test scenarios and test cases. Can someone tell me what a test scenario is?

Student 1
Student 1

Isn't it like a high-level idea of what we want to test?

Teacher
Teacher

Exactly! Test scenarios provide a broad view. Now, what about test cases? How are they different?

Student 2
Student 2

Aren't they more detailed instructions on how to test something?

Teacher
Teacher

Right again! Test cases are specific step-by-step instructions for testing. Can anyone give an example?

Student 3
Student 3

For instance, 'Verify login functionality' could be a scenario, and 'input valid credentials' would be a test case.

Teacher
Teacher

Great examples! Remember, scenarios are for planning, while test cases are for execution. Let’s summarize these points.

Boundary Value Analysis (BVA)

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Teacher
Teacher

Next, let’s talk about Boundary Value Analysis. Who can explain what this technique is?

Student 4
Student 4

Is it a way to test the edges of input range values where errors usually occur?

Teacher
Teacher

Right! We typically test values at the minimum and maximum edges. Can anyone give me an input range example for testing?

Student 1
Student 1

How about an age range of 18 to 60?

Teacher
Teacher

Perfect! So what minimum values would you test?

Student 2
Student 2

We would test 18, 17 for just below, and then 60, 61 for just above.

Teacher
Teacher

Exactly right! Always remember: test at the boundaries and just inside or outside those limits. Let’s summarize those key points.

Equivalence Partitioning (EP)

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Teacher
Teacher

Now let’s move on to Equivalence Partitioning. Who can explain what EP is all about?

Student 3
Student 3

I think it’s dividing the input data into classes that are treated the same.

Teacher
Teacher

Exactly! Each class represents a set of inputs that are expected to produce the same output. Can someone give me an example?

Student 4
Student 4

If ages are valid from 18 to 60, then 25 is valid, but 10 or 70 would be invalid.

Teacher
Teacher

Great example! Remember, to minimize testing, you only need to test one representative value from each class. Can someone summarize why this saves time?

Student 1
Student 1

Because we don't need to test every possible value, just one from each equivalent class.

Teacher
Teacher

Absolutely correct! A crucial point to remember. Let’s wrap up EP with those insights.

Decision Table Testing

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Teacher
Teacher

Next up is Decision Table Testing. How does this method help testers?

Student 2
Student 2

It organizes complex conditions and outcomes into a table which is easier to analyze.

Teacher
Teacher

Exactly! Can anyone give an example to illustrate this?

Student 3
Student 3

In a loan approval scenario, we could have different income and credit scores that dictate outcomes like approve, review, or reject.

Teacher
Teacher

Well done! Each row in the table helps visualize unique combinations of inputs. How about summarizing its benefits?

Student 4
Student 4

It helps check all combinations systematically, making it less likely to miss specific scenarios.

Teacher
Teacher

Correct! Let’s wrap up this session focusing on clarity and thoroughness.

State Transition Testing

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Teacher
Teacher

Finally, let’s discuss State Transition Testing. Who can tell me what it is?

Student 1
Student 1

It tests how a system transitions between different states based on events.

Teacher
Teacher

Right! This is essential for systems with states like login, logout, etc. Can anyone give an example?

Student 2
Student 2

In an ATM system, you’d test states like ‘Card Inserted’ and what happens when the PIN is entered.

Teacher
Teacher

Exactly! We must ensure the system correctly handles all valid and invalid transitions. Can someone summarize why this testing is crucial?

Student 4
Student 4

It verifies that the system behaves correctly throughout its lifecycle.

Teacher
Teacher

Perfect! Let’s wrap up by summarizing the importance of transition testing.

Introduction & Overview

Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.

Quick Overview

This section explores various test case design techniques that enhance testing efficiency and effectiveness.

Standard

The section differentiates between test scenarios and test cases, and presents key design techniques including Boundary Value Analysis, Equivalence Partitioning, Decision Table Testing, and State Transition Testing that aim to optimize test coverage and reduce effort.

Detailed

Test Case Design Techniques

This section delves into crucial test case design techniques that are essential for achieving optimal test coverage with minimal testing effort. It begins by clarifying the distinction between test scenarios and test cases, emphasizing how each serves a different purpose in the testing process.

Key Techniques Covered:
1. Boundary Value Analysis (BVA) – A technique focused on testing the edges of input ranges where defects are frequently discovered. BVA emphasizes testing values at the minimum and maximum boundaries, as well as just outside these boundaries.

  1. Equivalence Partitioning (EP) – This method segments input data into valid and invalid classes, effectively reducing the number of test cases needed while maintaining thorough testing coverage.
  2. Decision Table Testing – This tabular approach is used for scenarios where multiple conditions affect outcomes, helping testers to evaluate all possible combinations of inputs and their corresponding actions.
  3. State Transition Testing – Often applied in systems with various states, this testing technique examines how a system transitions from one state to another based on specific inputs or actions.

The section concludes with practical tips for effective test case design, reinforcing the philosophy that quality test design goes beyond achieving coverage — it emphasizes the selection of appropriate tests with minimal effort.

Audio Book

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Test Scenarios vs Test Cases

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Test Scenarios vs Test Cases

Definition: A high-level idea of what to test vs. A step-by-step set of instructions to test a feature.

Detail: Broad; covers multiple test conditions vs. Detailed; focuses on one specific path.

Usage: Useful in brainstorming vs. Used for execution, tracking, and reporting.

Detailed Explanation

Test scenarios are broad concepts or ideas about what needs to be tested within a system. For example, 'Verify login functionality' can be a test scenario. In contrast, a test case provides specific instructions on how to execute the test, such as the exact steps to input valid or invalid credentials. Test cases are detailed and focus on particular paths through the software. They are crucial for actual testing and tracking progress.

Examples & Analogies

Think of a test scenario like a 'recipe idea' for a dish, while test cases are the detailed step-by-step instructions for actually cooking that dish. The scenario gives you an idea of what you want to create, while the test case tells you exactly how to do it.

Boundary Value Analysis (BVA)

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Boundary Value Analysis (BVA)

Definition: A technique that tests the edges or boundaries of input ranges, where most defects tend to occur.

Where to Use: When input is taken in a range (e.g., age, price, quantity).

Example:
Field: Age (Allowed: 18–60)
| Test Case | Expected Result |
|------------------|-----------------|
| Lower boundary | Accepted |
| Just below lower | Rejected |
| Upper boundary | Accepted |
| Just above upper | Rejected |

Rule: Always test min, max, just below, just above, and the values in between.

Detailed Explanation

Boundary Value Analysis focuses on testing the limits of input values. For instance, if a system accepts ages between 18 and 60, we want to test not only 18 and 60 but also values just below (17) and just above (61) these limits. The rules imply that since defects often occur at the edges of input ranges, careful testing in these areas is crucial.

Examples & Analogies

Imagine you’re checking the height for a roller coaster ride. The minimum height is 48 inches. You would want to measure 48 inches (just right), 47 inches (too short), and even the maximum limit the coaster allows, like 72 inches, alongside 73 inches (too tall) to ensure safety regulations are met.

Equivalence Partitioning (EP)

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Equivalence Partitioning (EP)

Definition: Divides input data into equivalent classes, where one test from each class represents the whole group.

Where to Use: When input values can be grouped logically (valid/invalid classes).

Example:
Field: Age (Allowed: 18–60)
| Partition Type | Example Input | Expected Result |
|----------------|---------------|-----------------|
| Valid | 25 | Accepted |
| Invalid Low | 10 | Rejected |
| Invalid High | 70 | Rejected |

Tip: Save time by testing just one value from each class instead of every value.

Detailed Explanation

Equivalence Partitioning helps in reducing the number of test cases. Instead of testing every individual input value, it groups them into classes where all values in a class are expected to behave the same way. For example, if the allowed age is 18-60, testing one value from the valid range (like 25) suffices, while any invalid inputs would only need one test case each (like 10 and 70) to show they are rejected.

Examples & Analogies

Think about attending a movie based on age restrictions. Instead of checking every age, you just need to test a single valid age and a couple of invalid ages (like someone who's 10 and someone who's 70) to see if the system correctly identifies the allowed age range.

Decision Table Testing

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Decision Table Testing

Definition: A tabular method to handle complex business rules involving combinations of conditions and actions.

Where to Use: When there are multiple conditions and decision-based outputs (e.g., eligibility, pricing).

Example:
Scenario: Loan Approval
| Condition | Income > 30K | Credit Score > 700 | Action |
|------------------|---------------|--------------------|-------------|
| Yes | Yes | Approve Loan |
| Yes | No | Review |
| No | Yes | Review |
| No | No | Reject Loan |

Tip: Each row in the table represents a unique combination of inputs and outcomes.

Detailed Explanation

Decision Table Testing is effective when multiple criteria lead to varying outcomes. By organizing these interactions in a table, testers can visually represent different conditions and their respective actions. For instance, if a loan is dependent on both income and credit score, we can quickly see under what circumstances a loan is approved, reviewed, or rejected based on various combinations of these factors.

Examples & Analogies

Consider a simple recipe where you're deciding what to serve based on guest preferences and dietary restrictions. You could create a decision table that outlines the different combinations of preferences (vegan, gluten-free) and decide what dishes to serve based on that. This way, you can simplify menu planning significantly.

State Transition Testing

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State Transition Testing

Definition: Used to test system behavior for different states and transitions based on events or inputs.

Where to Use: When the system has multiple states (e.g., login, logout, lock) and transitions based on actions.

Example:
ATM Login Flow
| Current State | Input | Next State |
|---------------|----------------|----------------|
| Card Inserted | Correct PIN | Access Menu |
| Card Inserted | Wrong PIN (x3) | Card Blocked |
| Card Blocked | N/A | Logout |
| Access Menu | Logout | Card Ejected |

Tip: Helps ensure the system handles valid and invalid transitions correctly.

Detailed Explanation

State Transition Testing involves examining how a system behaves when it switches from one state to another based on inputs. For example, in an ATM system, entering the correct PIN moves the user from 'Card Inserted' to 'Access Menu', while entering the wrong PIN multiple times leads to the 'Card Blocked' state. This testing confirms that the system behaves correctly at each state and transition.

Examples & Analogies

Think about a smart door lock system. The lock can be in several states: locked, unlocked, or jammed. Depending on whether the right key is used or if the lock is manually manipulated, the lock moves to different states. Testing this ensures that the mechanism behaves correctly under various conditions, just as you’d check to make sure a door lock opens and closes properly based on the right keys and actions.

Summary of Techniques

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Summary of Techniques

Technique Best For Example Scenario
Boundary Value Analysis Edge conditions and numeric ranges Age limits, input ranges
Equivalence Partitioning Grouping valid/invalid inputs Form fields, password strength
Decision Table Testing Complex rule-based logic Loan approval, discount rules
State Transition Testing Systems with different states ATM, login/logout, cart flow

Detailed Explanation

This summary table encapsulates the core techniques we've discussed, highlighting where each is best applied. For example, Boundary Value Analysis works well for numeric ranges, such as age limits, whereas Equivalence Partitioning is ideal for scenarios involving valid and invalid inputs like form fields. Decision Tables help manage complex rules, and State Transition Testing is essential for systems that experience various states.

Examples & Analogies

Consider a grocery store. Different sections (like dairy, produce, bakery) represent various test techniques. Just as you wouldn’t use the same method to check for frost in the freezer section as you would to evaluate the bread freshness, each testing technique serves a unique purpose tailored to specific scenarios.

Tips for Test Designers

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Tips for Test Designers

  • Always combine EP and BVA when working with input fields.
  • Use Decision Tables to catch hidden combinations.
  • Use State Transition Diagrams for workflow-heavy applications.
  • Keep test cases traceable to requirements.

Detailed Explanation

These practical tips provide guidance for test designers to improve the effectiveness of their testing process. For example, combining Equivalence Partitioning and Boundary Value Analysis harnesses their strengths, making testing more efficient. Additionally, using Decision Tables can help uncover complex interactions that might not be immediately apparent. Keeping test cases aligned with requirements ensures that tests remain relevant and targeted.

Examples & Analogies

Consider a top chef using a checklist to ensure that ingredients are both high quality and in the ideal state before cooking. Each tip acts like a tool in their toolkit, making the testing process smoother and more thorough, ensuring that nothing essential is overlooked, much like ensuring each dish served is perfect.

Definitions & Key Concepts

Learn essential terms and foundational ideas that form the basis of the topic.

Key Concepts

  • Test Scenarios: High-level views of what to test, useful in planning.

  • Test Cases: Detailed steps for executing tests, crucial for tracking.

  • Boundary Value Analysis: Focus on edge testing for defect detection.

  • Equivalence Partitioning: Grouping inputs to minimize testing.

  • Decision Table Testing: Organizing complex conditions for clarity.

  • State Transition Testing: Examining behavior through different system states.

Examples & Real-Life Applications

See how the concepts apply in real-world scenarios to understand their practical implications.

Examples

  • Testing an age input field by applying BVA: Valid age of 18, below 18 (17), above 60 (61).

  • Using EP to test a password input by checking one case each from valid (e.g., 'StrongPassword1') and invalid classes (e.g., '123') to check acceptance rules.

Memory Aids

Use mnemonics, acronyms, or visual cues to help remember key information more easily.

🎵 Rhymes Time

  • BVA tests the edges, find the flaws, / Just outside, where logic withdraws.

📖 Fascinating Stories

  • Imagine a castle (the system) with gates (states). If you try to enter without a key (wrong PIN), you get rejected, reinforcing the need for State Transition Testing.

🧠 Other Memory Gems

  • EP: Group inputs like 'V' for Valid and 'I' for Invalid, ensuring you only test once from each class.

🎯 Super Acronyms

BVA

  • Boundary Values Are the key to uncovering errors.

Flash Cards

Review key concepts with flashcards.

Glossary of Terms

Review the Definitions for terms.

  • Term: Test Scenario

    Definition:

    A high-level concept of what to test, often representing a feature or a requirement.

  • Term: Test Case

    Definition:

    A detailed step-by-step set of instructions designed to verify particular aspects of a feature.

  • Term: Boundary Value Analysis (BVA)

    Definition:

    A testing technique that focuses on the edges or boundaries of input ranges to find defects.

  • Term: Equivalence Partitioning (EP)

    Definition:

    A method of dividing input data into valid and invalid equivalence classes to reduce the number of tests necessary.

  • Term: Decision Table Testing

    Definition:

    A tabular approach used to evaluate combinations of inputs and their corresponding actions.

  • Term: State Transition Testing

    Definition:

    A technique for testing the behavior of the system based on different states and transitions.