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Staying current and preparing for interviews: questions

Questions on staying current and preparing for interviews: warm-ups, then what each harder question tests and how a good answer starts.

6 questions: 1 warm-up and 5 with model answers · Levels: Fresher to senior

Warm-up questions

Short questions with short answers, each answered in full.

Fresher to mid

Which Dart version introduced records and patterns, and what does a package have to do to use them?

Answered in the lesson What changed from Dart 3.0 to 3.13

Questions with model answers

What each question tests, the first step of a good answer and the follow-ups to expect.

Mid to senior

A package with 80 files and sdk '>=2.19.0 <3.0.0' must reach the current language version within a week. Give the order of the steps, say what runs automatically and what needs a person, and how you know each step is safe to merge.
What it tests

Planning an upgrade in small steps, knowing that the language version follows the lower bound after pub get, and separating mechanical changes from changes of meaning.

First step

Run the package and its tests exactly as they are and record the result. Then raise the lower bound to 3.0, run pub get, and count the analyzer errors before you change any code.
Follow-ups
- Why do you run dart pub get after every change to the SDK constraint?
- Which changes will dart fix not make for you?
- Where does the formatting change go, and why?
From the lesson What changed from Dart 3.0 to 3.13
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In the answer:
- Model answer
- Follow-up answers
- Common mistakes
- Rubric
- Variants
- about 3 minutes
Mid to senior

You inherit a wiki that says switch needs break, dart migrate upgrades a package to null safety, and macros arrive soon. How do you check each claim against the current SDK, and what do you write in its place?
What it tests

Checking documentation against the installed SDK and the official changelog and blog, instead of repeating it, and writing corrections that name the version.

First step

Turn each claim into a command or a file you can run on the current SDK, and keep the output. Where a claim is about a plan, such as macros, look for the Dart team's own statement instead.
Follow-ups
- Which claim can be checked by running code and which by reading a source?
- How do you word a correction so that it stays true for the next release?
- How would you stop the same claims coming back?
From the lesson What changed from Dart 3.0 to 3.13
Model answer, Pro.
In the answer:
- Model answer
- Follow-up answers
- Common mistakes
- Rubric
- Variants
- about 3 minutes
Fresher to mid

An interviewer shows eight lines with a Future constructor, a scheduleMicrotask call, an async body with one await, and a Future.delayed with zero duration, and asks for the print order. You have ninety seconds. How do you answer?
What it tests

Stating the order of synchronous code, microtasks and events, applying it to an async function, and offering a run as evidence.

First step

Mark each line as synchronous, microtask or event before you say anything. An async body is synchronous up to its first await, and the code after the await is a microtask.
Follow-ups
- What changes if the await is on a Future.delayed of 10 milliseconds?
- Where does the output of a microtask that schedules another microtask appear?
- How would you check your answer if you had a laptop?
From the lesson Dart interview preparation
Model answer, Pro.
In the answer:
- Model answer
- Follow-up answers
- Common mistakes
- Rubric
- Variants
- about 3 minutes
Fresher to senior

A colleague says: "A final list is immutable, and const lists are slower because they are checked at run time." Correct both statements, and show each correction with a small program.
What it tests

Telling variable immutability from object immutability, knowing canonical constants, and replacing opinion with a run.

First step

Split the claim into two. For each half, write the shortest program whose output would settle it, and say what you expect to see before you run it.
Follow-ups
- What does identical tell you about two const literals?
- Is a list inside a const object mutable?
- When is const a design choice rather than a performance one?
From the lesson Dart interview preparation
Model answer, Pro.
In the answer:
- Model answer
- Follow-up answers
- Common mistakes
- Rubric
- Variants
- about 2 minutes
Mid to senior

You get a 45-minute coding task in Dart: retry an async call with a timeout. Walk through how you spend the time and what you say aloud at each stage.
What it tests

Planning a short coding session, writing tests first, asking about edge cases, communicating while coding, and closing with a summary of cost and next steps.

First step

Restate the task and name two edge cases before you write anything: zero attempts, and an attempt that never completes. Then write the signature and one failing test.
Follow-ups
- Which edge cases would you handle, and which would you only mention?
- How do you test the timeout without waiting a real second?
- What do you say in the last five minutes?
From the lesson Dart interview preparation
Model answer, Pro.
In the answer:
- Model answer
- Follow-up answers
- Common mistakes
- Rubric
- Variants
- about 3 minutes

All Dart (3.13) interview questions · The Dart (3.13) track

Warm-up questions

Which Dart version introduced records and patterns, and what does a package have to do to use them?

Questions with model answers

A package with 80 files and sdk '>=2.19.0 <3.0.0' must reach the current language version within a week. Give the order of the steps, say what runs automatically and what needs a person, and how you know each step is safe to merge.

You inherit a wiki that says switch needs break, dart migrate upgrades a package to null safety, and macros arrive soon. How do you check each claim against the current SDK, and what do you write in its place?

An interviewer shows eight lines with a Future constructor, a scheduleMicrotask call, an async body with one await, and a Future.delayed with zero duration, and asks for the print order. You have ninety seconds. How do you answer?

A colleague says: "A final list is immutable, and const lists are slower because they are checked at run time." Correct both statements, and show each correction with a small program.

You get a 45-minute coding task in Dart: retry an async call with a timeout. Walk through how you spend the time and what you say aloud at each stage.