Catch and fix a local regression with RWX

Break a calculation in the sample project, inspect its failed test in RWX, and validate the fix before pushing.

In this exercise, deliberately break one calculation in the sample project, inspect the failure in RWX, then restore it—all before committing or pushing. Use the public project and workflow from the quickstart.

Before you start

Complete the quickstart, including its passing run. Open your terminal in the rwx-quickstart clone and check the source file:

git diff -- src/index.js

This command should print nothing. Use the original example source for this exercise; preserve any changes you have already made before continuing. Your untracked .rwx/quickstart.yml can stay as it is. You need no local Node.js installation and no new repository access.

1. Make a change that fails a test

Open src/index.js. In calculateTotal, change:

total += item.price * item.quantity;

to:

total += item.price;

The calculation now adds each item’s price once, regardless of its quantity. Inspect the change:

git diff -- src/index.js

The diff should contain:

-    total += item.price * item.quantity;
+    total += item.price;

Keep the edit local. The RWX CLI sends local changes with a new run, so you can check this change before committing or pushing it.

2. Run the test task

rwx run .rwx/quickstart.yml --wait --title "Test a local change: failure" --target test

The --target test option includes the test task and its dependencies: code, node, and npm-install. The separate lint task is outside this run. The existing filter on npm-install lets RWX reuse dependency installation when only this source file changes.

The CLI should report:

Run result status: failed

That is the expected checkpoint: a cloud test has caught the local regression.

3. Inspect the assertion

Open the run URL printed by the CLI. Select Tests, then expand Output under Index functions > calculateTotal > should calculate total for valid items.

Look for 1 Failed, 19 Successful, and this assertion:

Expected: 35
Received: 15

The test uses two items: a price of 10 with quantity 2, and a price of 5 with quantity 3. The correct total is 10 * 2 + 5 * 3 = 35. The changed calculation returns 10 + 5 = 15.

4. Restore the calculation and start a new run

In src/index.js, restore the original line:

total += item.price * item.quantity;

Start a new run with the current local files:

rwx run .rwx/quickstart.yml --wait --title "Test a local change: fixed" --target test

The CLI should report Run result status: succeeded. Open the new run’s Tests tab and confirm 20 Successful.

Restoring the exact source from the quickstart can also make the test task a cache hit: RWX already has a successful result for those inputs. A new run checks the current input state and can reuse that result.

Use rwx run after editing your files. Retrying the earlier failed run uses that run’s original inputs; it does not upload the local fix.

5. Check your local source

git diff -- src/index.js

It should print nothing again. You have completed a local failure-and-fix loop in cloud CI without a commit or push.

If a step fails

What you see	What to do
The first run succeeds	Check that you saved total += item.price; in src/index.js and ran from the example clone
A setup task fails before tests start	Open the failed task’s output; confirm the quickstart still runs with its original configuration
The restored run still fails	Restore the quantity multiplication and start a new rwx run; check the new run URL
The restored test is Cached	Open Tests and confirm 20 Successful; the cache contains a successful result for the restored inputs

Continue with running commands in a cloud sandbox to reuse one environment across commands and bring cloud file edits back to your machine.