State transition testing in Testing Fundamentals - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a state transition function that moves from 'locked' to 'unlocked'.

Testing Fundamentals

def transition(state, event):
    if state == 'locked' and event == 'coin':
        return [1]
    return state

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

A'locked'

B'open'

C'unlocked'

D'closed'

Attempts:

3 left

💡 Hint

Common Mistakes

Returning the same state instead of changing it.

The function should return 'unlocked' when the state is 'locked' and the event is 'coin'.

2fill in blank

medium

Complete the code to check if the current state is 'unlocked' before locking it again.

Testing Fundamentals

def transition(state, event):
    if state == [1] and event == 'push':
        return 'locked'
    return state

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

A'locked'

B'open'

C'closed'

D'unlocked'

Attempts:

3 left

💡 Hint

Common Mistakes

Checking for the wrong state before locking.

The state must be 'unlocked' to transition to 'locked' when the event is 'push'.

3fill in blank

hard

Fix the error in the transition function to handle an invalid event by returning the current state.

Testing Fundamentals

def transition(state, event):
    if state == 'locked' and event == 'coin':
        return 'unlocked'
    elif state == 'unlocked' and event == 'push':
        return 'locked'
    else:
        return [1]

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

ANone

Bstate

C'invalid'

D'error'

Attempts:

3 left

💡 Hint

Common Mistakes

Returning an error string instead of the current state.

When the event is invalid, the function should return the current state unchanged.

4fill in blank

hard

Fill both blanks to complete the state transition dictionary and the function that uses it.

Testing Fundamentals

transitions = {
    'locked': {'coin': [1],
    'unlocked': {'push': [2]
}

def transition(state, event):
    return transitions.get(state, {}).get(event, state)

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

A'unlocked'

B'locked'

C'open'

D'closed'

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping the states or using incorrect state names.

The dictionary maps 'locked' + 'coin' to 'unlocked' and 'unlocked' + 'push' to 'locked'.

5fill in blank

hard

Fill all three blanks to create a test case that verifies the transition from 'locked' to 'unlocked' on 'coin' event.

Testing Fundamentals

def test_locked_to_unlocked():
    initial_state = [1]
    event = [2]
    expected_state = [3]
    actual_state = transition(initial_state, event)
    assert actual_state == expected_state, f"Expected {expected_state}, got {actual_state}"

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

A'locked'

B'coin'

C'unlocked'

D'push'

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up event names or expected states.

The test sets initial state to 'locked', event to 'coin', and expects 'unlocked' after transition.

Practice

1. What is the main purpose of state transition testing in software testing?

easy

A. To check how the system behaves when moving from one state to another

B. To test the speed of the software under load

C. To verify the user interface design

D. To check the installation process of the software

Solution

1. Step 1: Understand the concept of state transition testing

   State transition testing focuses on how software changes from one state to another based on events or inputs.

2. Step 2: Match the purpose with the options

   To check how the system behaves when moving from one state to another correctly describes checking system behavior during state changes, which is the core of state transition testing.

3. Final Answer:

   To check how the system behaves when moving from one state to another -> Option A

4. Quick Check:

   State transition testing = check state changes [OK]

Hint: Focus on system behavior during state changes [OK]

Common Mistakes:

• Confusing state transition testing with performance testing
• Thinking it tests UI design
• Mixing it with installation testing

2. Which of the following is the correct way to represent a state transition in a test case?

easy

A. State A --(event)--> State B

B. State A + State B = Event

C. Event = State A and State B

D. State A * Event = State B

Solution

1. Step 1: Recall the notation for state transitions

   State transitions are usually shown as one state moving to another state triggered by an event, written as State A --(event)--> State B.

2. Step 2: Compare with given options

   State A --(event)--> State B matches the standard notation. Other options use incorrect symbols or formats.

3. Final Answer:

   State A --(event)--> State B -> Option A

4. Quick Check:

   Correct notation = State A --(event)--> State B [OK]

Hint: Look for arrow with event in parentheses [OK]

Common Mistakes:

• Using incorrect symbols like + or *
• Confusing event placement
• Mixing states and events in wrong order

3. Consider a system with states: Locked and Unlocked. The event InsertCoin moves it from Locked to Unlocked. What is the next state after InsertCoin if the system is currently Locked?

medium

A. Locked

B. Unlocked

C. Error

D. Unknown

Solution

1. Step 1: Identify current state and event

   The system is currently in the Locked state, and the event InsertCoin occurs.

2. Step 2: Apply the state transition rule

   According to the rule, InsertCoin moves the system from Locked to Unlocked state.

3. Final Answer:

   Unlocked -> Option B

4. Quick Check:

   Locked + InsertCoin = Unlocked [OK]

Hint: Follow event rules from current state [OK]

Common Mistakes:

• Assuming state stays the same after event
• Choosing error or unknown without reason
• Ignoring the given transition rule

4. A tester wrote a state transition test but missed the event that moves the system from Idle to Active. What is the likely problem in the test?

medium

A. The test will check UI elements incorrectly

B. The test will run faster

C. The test will cause a syntax error

D. The test will not cover all possible state changes

Solution

1. Step 1: Understand the missing event impact

   Missing the event means the test does not check the transition from Idle to Active state.

2. Step 2: Identify the consequence on test coverage

   Without this event, the test misses a possible state change, reducing coverage and possibly missing bugs.

3. Final Answer:

   The test will not cover all possible state changes -> Option D

4. Quick Check:

   Missing event = incomplete state coverage [OK]

Hint: Check all events for full coverage [OK]

Common Mistakes:

• Thinking missing event causes syntax error
• Assuming test speed changes
• Confusing state transitions with UI checks

5. You have a vending machine with states: Idle, HasMoney, and Dispensing. Events are InsertCoin, SelectItem, and DispenseItem. Which test case best checks the transition from HasMoney to Dispensing?

hard

A. Start in Idle, SelectItem, then InsertCoin

B. Start in Dispensing, InsertCoin, then SelectItem

C. Start in Idle, InsertCoin, then SelectItem

D. Start in HasMoney, DispenseItem, then InsertCoin

Solution

1. Step 1: Identify the transition from HasMoney to Dispensing

   The event that moves the machine from HasMoney to Dispensing is SelectItem.

2. Step 2: Find the test case that triggers this transition

   Start in Idle, InsertCoin, then SelectItem starts Idle, InsertCoin (moves to HasMoney), then SelectItem (moves to Dispensing), correctly testing the transition.

3. Final Answer:

   Start in Idle, InsertCoin, then SelectItem -> Option C

4. Quick Check:

   HasMoney + SelectItem = Dispensing [OK]

Hint: Trace events to reach target transition [OK]

Common Mistakes:

• Starting in wrong state
• Using events in wrong order
• Ignoring correct event for transition