Python for software engineers interviews

Work in the tool while you explain your decisions.

Choose a role and level. Each interview has a new task, follow-up questions and a report that checks your work and your explanation.

Take the assessment Choose an interview

Speak or type. Sign in to save your results across devices.

Timed assessment

12 practical questions
90 minutes
Mid level

Questions are drawn from a bank of 36. Your report includes a skill breakdown and lessons to practice next.

Start assessment

Practice interviews

Junior tasks cover the fundamentals. Mid and senior tasks add debugging, changing requirements and review decisions.

Position

10 interviews

Software engineer
Junior
20 min

Cove independent manifest

Copy each manifest row. Add delta to the first value of each nonempty copied row, then return original rows followed by copied rows. The originals must keep their values. Empty rows remain present.

Start interview

Skills and rubricnested-copy-boundary

The outer list owns references to rows. Copying each row keeps the original values unchanged when the copied first item changes.
For [[0],[0]] with delta -2, the output is [[0],[0],[-2],[-2]]. Empty rows must remain empty.
Runs a concrete example and describes its expected result before declaring success.

Backend engineer
Junior
20 min

Cove deferred adjustments

Build one callback per offset, then invoke them after the loop with base. Return each base plus its own offset in input order. Bind values when callbacks are created.

Start interview

Skills and rubricclosure-binding-time

A default argument captures each loop value at callback creation. Calling all callbacks later then preserves the distinct offsets.
With offsets [0] and base -3, the single result is -3. An empty callback list produces an empty result.
Runs a concrete example and describes its expected result before declaring success.

Test automation engineer
Junior
20 min

Cove packet batches

Write a generator inside the function that yields sums of consecutive batches of size values. Return the yielded sums as a list. Keep a final partial batch. size is at least 1.

Start interview

Skills and rubricstream-chunk-finalization

The generator tracks a batch item count because a zero total can still represent a nonempty batch. Each full batch resets both counters; a remaining count causes the generator to yield the tail.
Three zero values with size 2 produce [0,0]. A zero total is still a nonempty batch.
Runs a concrete example and describes its expected result before declaring success.

Software engineer
Mid
28 min

Cove resource audit

Use a context manager to record open, work and close, prefixing each event with label and a colon. If fail is true, raise ValueError during work and catch it outside the with block, appending label:handled. Return the trace. Cleanup must precede handled.

Start interview

Skills and rubriccontext-cleanup-on-failure

The context manager owns cleanup in finally. Exception handling outside with sees a resource that has already closed.
A failed operation returns [open,work,close,handled], while success omits handled.
Explains the runtime and storage limits: O(1) time and space per operation.

Backend engineer
Mid
28 min

Cove dispatch records

Create frozen dataclass dispatch records from equal-length names and priorities. Return names by ascending priority, preserving original order for ties. Duplicate names represent separate records.

Start interview

Skills and rubricstable-priority-order

A frozen dataclass records the fields. A key on priority alone relies on stable sorting to preserve tie order.
Names B,A with priorities 5,5 must stay B,A. Duplicate names must not disappear.
Explains the runtime and storage limits: O(n log n) time and O(n) records.

Test automation engineer
Mid
28 min

Cove retry counts

Count retry codes after stripping whitespace and casefolding. Skip empty normalized codes. Return a dictionary of counts. Repeated codes represent repeated retries.

Start interview

Skills and rubricfrequency-with-normalization

Counter accumulates each normalized event. Filtering blanks before counting keeps the empty key out of the result.
Straße and STRASSE share strasse with count 2. A batch of blanks returns an empty dictionary.
Explains the runtime and storage limits: O(n) expected time and O(k) distinct normalized codes.

Software engineer
Mid
28 min

Cove largest parcels

Use heapq to return the count largest parcel weights in descending order, retaining duplicates. A nonpositive count returns an empty list; a count above the input length returns every weight.

Start interview

Skills and rubricbounded-top-k

nlargest selects at most count entries and returns descending values. A small bounded heap avoids sorting a long input for a small count.
For weights [-5,0,-1] and count 9, return [0,-1,-5]. A count of zero selects nothing.
Explains the runtime and storage limits: O(n log k) time for small k and O(k) selected entries.

Backend engineer
Senior
35 min

Cove UTC handoffs

Parse ISO timestamps that include an explicit UTC offset. Return each instant in UTC with seconds precision and +00:00, in original order. Do not sort or discard repeats. Every input is valid and offset-aware.

Start interview

Skills and rubricaware-time-normalization

Aware datetime values identify instants. astimezone converts the same instant to UTC; replacing tzinfo only changes its label.
Defends the design using the changed constraint: Some records now omit offsets. Explain why guessing the server timezone is unsafe and propose a validation policy.
Relates O(n) time and O(n) returned timestamps to the input contract and names a test that would falsify the reasoning.

Test automation engineer
Senior
35 min

Cove paginated feed

Each pages item is JSON with items (an integer list) and next (a page index or null). Start at index 0, append items in page order and follow next. Return [-1] on a repeated page index. Empty pages input returns []. All referenced indices are valid. This is a local mocked transport.

Start interview

Skills and rubricmock-pagination-cycle

A visited-index set prevents cycles while the cursor controls traversal. Only the payload transport is mocked; pagination logic runs as Python.
Defends the design using the changed constraint: The API now retries a page after a transient error. Explain how retrying a request differs from encountering a cursor twice after successful processing.
Relates O(p + n) time for p pages and n items, with O(p) visited cursor state to the input contract and names a test that would falsify the reasoning.

Software engineer
Senior
35 min

Cove async receipts

Write an async entry function. Start one coroutine per value, yield control with asyncio.sleep(0), and return each value squared in original order after all tasks finish. Keep duplicate tasks. The workspace awaits your entry function.

Start interview

Skills and rubricasync-order-and-await

gather awaits all submitted coroutines and returns results in submission order. Each coroutine yields control at sleep before calculating its result.
Defends the design using the changed constraint: The source may contain a million values. Explain why creating every task at once is unsafe and propose a bounded worker queue.
Relates O(n) tasks and returned values; scheduling all work at once also needs O(n) memory to the input contract and names a test that would falsify the reasoning.

Choose your character

Python for software engineers interviews

Timed assessment

Practice interviews

Cove independent manifest

Cove deferred adjustments

Cove packet batches

Cove resource audit

Cove dispatch records

Cove retry counts

Cove largest parcels

Cove UTC handoffs

Cove paginated feed

Cove async receipts

Interview Hub access

Your Work Gym account