iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
To get an AI coding assistant to write a failing test before fixing a bug, separate the work into phases: describe the observed and expected behavior, ask for one focused test with no production-code edits, run it and confirm it fails for the right reason, then allow the smallest fix. This is a practical form of test-driven development (TDD), not a guarantee that the fix is correct or that a free model will always follow instructions.
Why the failing test comes first
A test written before the fix makes the intended behavior explicit and gives you a way to check that the bug is reproduced. If the assistant edits production code first, a later test may simply encode what the new implementation already does rather than independently establish what it should do.
The familiar TDD cycle is red, green, refactor: write and run a test that fails, make the minimum change needed to pass, then improve the code while keeping the tests green. The Government Digital Service (GDS) TDD guidance describes starting with desired behavior and using feedback to guide small changes. Martin Fowler likewise identifies refactoring as part of the cycle, not optional cleanup to forget once the tests pass.
Recommended Free Tools
How to run the test-first workflow with an AI assistant
1. Describe the bug as observable behavior
Give the assistant what a user or calling component sees: the action or input, the actual result, and the expected result. Include relevant context such as the affected module, error conditions, interactions with other components, and the repository’s test command and conventions. Avoid prescribing an implementation unless it is essential; the test should express the behavior, not a preferred internal design.
#1 Best Overall
- 1. Emotional Interaction: This chatbot can recognise and respond to your emotions, offering a more personalised and human-like interaction
- 2. A wide variety of emojis: The bot comes with over 100 lively emojis, covering a range of emotions from happy and shy to mischievous, allowing you to switch between them freely depending on your current mood
- 3.Perfect Holiday Gift：A fun and interactive companion ideal for birthdays, holidays, and special occasions. Great for kids, friends, and anyone who enjoys smart gadgets
- 4. Compact and Convenient: Its compact dimensions make it an ideal companion for your desk or shelf, adding a touch of technological sophistication to any space
- 5. Intelligent Voice: Equipped with several leading AI large language models, including DeepSeek and Doubao, it supports intelligent voice dialogue and seamless switching between models, creating an intelligent desktop companion that understands the user and meets smart needs across all scenarios
For example, specify that a particular input currently produces an error but should return a defined result. Make the expected outcome concrete enough to assert. GDS recommends identifying desired behaviors across happy paths, errors, and interactions, then taking one behavior at a time.
2. Request one test, and prohibit production edits
Ask the assistant to add a single focused test using the project’s existing test framework and patterns. State plainly that it must not change production code in this phase. One test per increment helps keep the failure interpretable and the eventual fix bounded.
Useful project guidance includes how tests are named, where they belong, how fixtures or mocks are used, and the exact command to run them. Microsoft’s VS Code documentation for custom agents illustrates this separation: a red-phase agent writes failing tests without implementing the feature, and the workflow hands off to a distinct implementation phase. The documentation also recommends project-specific instructions so generated tests better match local conventions and scenarios.
3. Run the test and inspect the failure
Do not treat a generated test file as proof that the bug has been reproduced. Run the new test yourself, or verify the assistant’s reported command and output, and check that the test fails because the behavior is missing or wrong.
Rank #2
- Compact and Portable: The ATOM VOICE is designed with a small form factor, measuring only 24 * 24 * 17 mm. Its compact size makes it highly portable and convenient for on-the-go use.
- Voice Interaction and AI Capabilities: The built-in microphone and speaker allow for voice interaction, enabling voice control, story-telling, and other AI-based functions. The device can be programmed to access cloud platforms like AWS and Baidu, expanding its capabilities.
- Wireless Music Playback: Utilizing the BT capabilities of the ESP32, you can wirelessly play music from your mobile phone or tablet, providing a seamless and convenient audio experience.
- Versatile Connectivity: The ATOM VOICE supports 2.4G Wi-Fi IEEE 802.11b/g/n, allowing for easy and reliable wireless connectivity to the internet and other devices.
- RGB LED Status Display: The embedded RGB LED (SK6812) visually displays the connection status, providing a clear indication of the device's operational mode and status.
- Useful red: the test executes and reports that the actual result differs from the expected behavior.
- Not useful red: the test cannot compile, setup fails, a dependency is missing, or an unrelated test breaks first.
GDS says the test should fail “in the way you expect.” If the failure is caused by test code or environment setup, correct that problem before moving on; otherwise, the red phase has not established that the test captures the bug.
4. Allow the smallest implementation change
Once the failure is meaningful, ask the assistant to change production code only as much as needed to make the new test and relevant existing tests pass. Keep the test fixed during this phase unless you discover that its expectation was wrong; if so, explain the correction rather than quietly weakening the assertion.
Have the assistant run the stated tests and show the command and result. Microsoft’s VS Code example uses a handoff from the test-writing phase to an implementation phase that makes a minimal change and runs tests. The xUnit.net TDD guidance also emphasizes starting a behavioral change with a test that captures the intended behavior.
Free tools Windows power users keep installed
One-click scans. No signup required.
5. Refactor only after the behavior is green
After the new test and the relevant suite pass, ask for structural improvements separately: remove duplication, clarify names, or simplify the design without changing behavior. Then rerun the tests. Keeping refactoring distinct from the fix makes it easier to identify which change caused a regression.
Fowler’s overview of test-driven development, updated December 11, 2023, describes the red-green-refactor cycle and warns that neglecting refactoring can leave code in a messy state.
Prompt template for the red phase
Adapt this to the repository and the bug:
Observed behavior: [describe what happens, including the input or action].
Expected behavior: [describe the result that should be observable].
Using this repository's existing test conventions, add one focused test for
that behavior. Do not edit production code. Tell me the exact test command to
run and what failure would show that the bug is reproduced.After confirming the failure, start a separate green-phase request: implement the smallest production-code change that makes this test and the relevant existing tests pass. Do not modify the test unless its expectation is demonstrably incorrect; run the tests and report the command and result. A separate refactor request can follow once the tests are green.
This is a workflow prompt, not a compliance mechanism. Microsoft’s guidance shows how to structure separate agents and handoffs in VS Code; it does not establish that any particular model, free or paid, will obey every instruction or produce more reliable fixes.
Quick wins for a faster PC:
Clear out junk files and repair common Windows errorsFree Scan →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Repair Windows errors before they cause bigger problemsFix Now →When a strict test-first loop is a good fit
Use the full sequence when the behavior is clear, the bug can be reproduced locally, and the relevant test feedback arrives quickly. GDS identifies unit and component-integration tests as useful settings for TDD. A well-scoped test is particularly valuable when a bug could easily be “fixed” by changing the wrong behavior or when a regression must be guarded against.
It is a weaker fit when expected behavior is still ambiguous or the only relevant check is a slow acceptance test spanning multiple components that cannot run locally. GDS notes that long feedback loops make a tight TDD cycle less effective. In that case, first clarify the expected behavior or choose a faster local check that gives meaningful feedback; keep the changes incremental rather than pretending a slow test is a quick red-green loop.
Test-first is a choice of workflow, not a rule for every task. JetBrains’ IntelliJ IDEA TDD tutorial presents it as a development approach and demonstrates it with Java and JUnit 5. The useful decision is whether you can state a meaningful contract and get fast, interpretable feedback.
What to review before accepting the fix
- Does the assertion describe a meaningful contract? Prefer externally observable behavior over details that merely mirror the implementation.
- Was the red failure for the intended reason? A malformed test or broken setup does not reproduce the bug.
- Is the change appropriately small? Unrelated cleanup makes it harder to assess whether the bug fix caused a new problem.
- Did the assistant show actual test execution? A claimed test file or unverified assertion is not evidence that tests ran.
- Did the relevant suite pass after implementation and refactoring? Check the command and result rather than relying on a summary.
The central discipline is to make the expected behavior testable before implementation begins, then demand visible feedback at each phase. Kent Beck’s line, quoted in GDS guidance, captures the approach: “For each desired change, make the change easy (warning: this may be hard), then make the easy change.”
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
