Test-driven development (TDD) in Software Engineering - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to describe the first step of TDD.

Software Engineering

In TDD, the first step is to write a [1] before writing any actual code.

Drag options to blanks, or click blank then click option'

Atest

Bfunction

Cdocumentation

Dcomment

Attempts:

3 left

💡 Hint

Common Mistakes

Writing the function before the test

Writing documentation first instead of a test

The first step in Test-driven development is to write a test that defines a desired improvement or new function.

2fill in blank

medium

Complete the sentence to explain the TDD cycle.

Software Engineering

The TDD cycle is often described as Red, [1], Refactor.

Drag options to blanks, or click blank then click option'

ARun

BRewrite

CReview

DGreen

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing 'Green' with 'Run' or 'Review'

Thinking the cycle is Red, Run, Refactor

In TDD, 'Red' means the test fails, 'Green' means the test passes, and then you Refactor the code.

3fill in blank

hard

Fix the error in the TDD description.

Software Engineering

In TDD, you write the code first, then write tests to check it. This is called [1].

Drag options to blanks, or click blank then click option'

ATest-driven development

BBehavior-driven development

CTest-last development

DCode-first development

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing TDD with writing tests after code

Mixing up different development approaches

Writing code first and tests later is called Test-last development, which is the opposite of TDD.

4fill in blank

hard

Fill both blanks to complete the TDD workflow.

Software Engineering

First, write a failing [1]. Then, write just enough [2] to pass it.

Drag options to blanks, or click blank then click option'

Atest

Bcode

Cdocumentation

Dscript

Attempts:

3 left

💡 Hint

Common Mistakes

Writing code before the test

Confusing documentation with tests

The TDD workflow starts by writing a failing test, then writing just enough code to pass that test.

5fill in blank

hard

Fill all three blanks to describe the benefits of TDD.

Software Engineering

TDD helps improve [1], reduces [2], and encourages [3] design.

Drag options to blanks, or click blank then click option'

Acode quality

Bbugs

Cbetter

Dfaster

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'faster' instead of 'better' for design

Mixing up benefits with unrelated terms

TDD improves code quality, reduces bugs, and encourages better design practices.

Practice

1. What is the main purpose of Test-driven development (TDD)?

easy

A. To write tests before writing the actual code

B. To write code first and then tests later

C. To avoid writing any tests

D. To write documentation before coding

Solution

1. Step 1: Understand TDD process

   TDD means writing tests before the actual code to guide development.

2. Step 2: Identify the main goal

   The main goal is to ensure code correctness by writing tests first.

3. Final Answer:

   To write tests before writing the actual code -> Option A

4. Quick Check:

   TDD = Write tests first [OK]

Hint: Remember: TDD starts with tests, not code [OK]

Common Mistakes:

• Thinking code is written before tests
• Confusing TDD with writing documentation
• Believing tests are optional in TDD

2. Which of the following is the correct order of steps in the TDD cycle?

easy

A. Write code, write test, refactor

B. Write test, write code, refactor

C. Refactor, write code, write test

D. Write test, refactor, write code

Solution

1. Step 1: Recall TDD cycle steps

   The TDD cycle is: write a failing test, write code to pass it, then refactor.

2. Step 2: Match the correct sequence

   Write test, write code, refactor matches this order exactly.

3. Final Answer:

   Write test, write code, refactor -> Option B

4. Quick Check:

   TDD cycle = Test -> Code -> Refactor [OK]

Hint: TDD always starts with a failing test [OK]

Common Mistakes:

• Writing code before tests
• Refactoring before writing code
• Mixing the order of steps

3. Consider this TDD scenario:
1. Write a test that expects function add(2, 3) to return 5.
2. Implement add function as def add(a, b): return a - b
3. Run the test.
What will be the test result?

medium

A. Syntax error in function definition

B. Test passes successfully

C. Test fails because the function returns wrong result

D. Test is skipped automatically

Solution

1. Step 1: Analyze the function implementation

   The function subtracts b from a instead of adding them.

2. Step 2: Compare expected and actual results

   Calling add(2, 3) returns -1, but test expects 5, so test fails.

3. Final Answer:

   Test fails because the function returns wrong result -> Option C

4. Quick Check:

   Wrong function logic = Test fails [OK]

Hint: Check if function logic matches test expectation [OK]

Common Mistakes:

• Assuming test passes despite wrong logic
• Confusing syntax error with logic error
• Thinking tests skip automatically

4. You wrote a test first but it never fails even before implementing the code. What is the likely problem?

medium

A. Test is not written correctly to check the feature

B. Code is already perfect and needs no changes

C. Test framework is broken and skips tests

D. You forgot to run the test

Solution

1. Step 1: Understand TDD failing test requirement

   In TDD, the first test should fail because code is not implemented yet.

2. Step 2: Identify why test never fails

   If test never fails, it likely does not check the feature properly or has wrong assertions.

3. Final Answer:

   Test is not written correctly to check the feature -> Option A

4. Quick Check:

   Failing test means correct test setup [OK]

Hint: First test must fail to guide development [OK]

Common Mistakes:

• Assuming code is perfect without implementation
• Blaming test framework without checking test code
• Forgetting to run tests

5. You want to use TDD to develop a function that returns only even numbers from a list. Which sequence of steps best follows TDD principles?

hard

A. Write code and tests simultaneously, then refactor

B. Write code to filter evens, then write tests to check it

C. Write tests after finishing all code

D. Write a test for filtering evens, write code to pass test, then refactor code

Solution

1. Step 1: Recall TDD workflow

   TDD requires writing a failing test first, then code to pass it, then refactoring.

2. Step 2: Match steps to TDD

   Write a test for filtering evens, write code to pass test, then refactor code follows this exact sequence for developing the function.

3. Final Answer:

   Write a test for filtering evens, write code to pass test, then refactor code -> Option D

4. Quick Check:

   TDD = Test -> Code -> Refactor [OK]

Hint: Always start with a test that fails for new feature [OK]

Common Mistakes:

• Writing code before tests
• Writing tests after code completion
• Mixing test and code writing steps