ISTQB CTAL-TTA Exam - Topic 1 Question 42 Discussion

Actual exam question for ISTQB's CTAL-TTA exam

Question #: 42
Topic #: 1

A unit test should be isolated Which option correctly describes the meaning of 'isolated' as a characteristic of a unit test?

SELECT ONE OPTION

Whenever it is run under the same conditions, it should produce the same results.

AIt should only test the functionality related to it.

Bit should provide immediate feedback.

CIt should test only the code for which it was originally written

Show Suggested Answer

Suggested Answer: C

The term 'isolated' as a characteristic of a unit test means that it should test only the code for which it was originally written. This ensures that the unit test is focused, minimizes dependencies on other parts of the codebase, and errors can be traced back to specific units without ambiguity .

by Jerry at Nov 24, 2025, 12:37 AM

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Tresa

9 hours ago

B seems important too, but I guess isolation is the priority.

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Lavera

6 days ago

Wait, is it really just about testing related functionality?

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Matthew

11 days ago

I thought it was more about consistent results, not just functionality.

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Reita

16 days ago

Totally agree, isolation is key!

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Leana

21 days ago

A) It should only test the functionality related to it.

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Lenna

26 days ago

Haha, I bet the developers who write these tests have to be really careful not to let their coffee spill on the keyboard!

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Shayne

1 month ago

C) It should test only the code for which it was originally written. This is the key to isolation.

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Milly

1 month ago

That's right, a unit test should be focused on testing a specific, isolated piece of functionality.

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Paulina

1 month ago

A) It should only test the functionality related to it.

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Deeann

2 months ago

I thought isolation meant that a test should only focus on the code it was written for, which sounds like option C. But now I'm second-guessing myself.

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Elinore

2 months ago

I practiced a similar question where isolation was emphasized, and I think it was about testing specific functionalities. So, I would lean towards option A as well.

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Grover

2 months ago

I'm a bit unsure about this one. I feel like all the options touch on aspects of unit testing, but I think A is the most relevant to isolation.

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Clement

2 months ago

I remember discussing how isolation in unit tests means they shouldn't depend on other tests or external systems. So, I think option A makes sense.

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Eveline

2 months ago

I'm pretty sure 'isolated' means the test should be self-contained and not rely on any external factors. So it should consistently produce the same results when run under the same conditions. I think option A is the way to go.

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Tonette

2 months ago

Okay, I've got this. 'Isolated' means the unit test is only testing the code it was written for, and not any dependencies or other parts of the system. So option A is the correct answer here.

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Orville

3 months ago

Exactly, isolation is about testing one functionality at a time.

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Felice

3 months ago

But C feels too narrow. A covers more ground.

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Nikita

3 months ago

Hmm, I'm a bit confused on this one. I know a unit test should be isolated, but I'm not sure if that means it has to produce the same results every time, or if it just needs to focus on a specific piece of code. I'll have to think this through a bit more.

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Kiera

3 months ago

I think the key here is that the unit test should only be testing the specific functionality it was designed for, and not any other parts of the system. That's what 'isolated' means in this context.

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