Axon·Software Engineer·Technical Phone Screen·Intermediate

Intermediate

Apr 2026

Summary

Phone screen for a software engineer role at Axon, one round of system design. The question came from the interviewer's actual project rather than a standard bank, which made it feel a bit more unpredictable than usual.

Questions Asked (1)

Design a system that can manage and execute various types of tests. Define how tests are represented, scheduled, and run.

System DesignTechnical Trade-offsAdaptability & Ambiguity

Author's notes

Went in with a job scheduler mental model and kind of just ran with it.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the scope and requirements of the test management system, such as the types of tests, scale, and execution environment. Then propose a high-level architecture that separates test representation, scheduling, and execution, and dive into each component with trade-offs. Finally, discuss how the system handles failures, scalability, and extensibility.

Pro tip: Emphasize idempotency and isolation in test execution to avoid flaky tests and ensure reliable results, and mention how you would handle test dependencies and parallelism.

1. Clarify Requirements

Ask questions to understand the types of tests (unit, integration, e2e), expected scale (number of tests, frequency), and constraints (time, resources). This shows you can handle ambiguity and scope the problem.

2. Define Test Representation

Propose a schema or data model for tests, including metadata like ID, type, dependencies, parameters, and expected outcomes. Consider using a declarative format (e.g., YAML/JSON) for flexibility.

3. Design Scheduling

Outline a scheduling component that queues and dispatches tests based on priorities, dependencies, and available resources. Discuss strategies like FIFO, priority queues, or dependency graphs.

4. Design Execution

Describe how tests are run in isolated environments (e.g., containers, VMs), with mechanisms for reporting results, handling failures, and retries. Mention scalability via worker pools and autoscaling.

5. Discuss Trade-offs and Extensibility

Highlight trade-offs between simplicity and scalability, and how the system can be extended for new test types or integrations. Address monitoring, logging, and alerting.

Key Points to Mention

Use of a message queue (e.g., Kafka, RabbitMQ) for decoupling scheduling and execution.
Containerization (e.g., Docker, Kubernetes) for isolation and reproducibility.
Dependency management between tests (e.g., DAGs) to enable parallel execution where possible.
Idempotency and retry mechanisms to handle transient failures.
Scalability considerations: horizontal scaling of workers, sharding of test queues.
Observability: logging, metrics, and tracing for debugging and performance monitoring.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.