Module 07 — Practice: migration without red tests

Time: 210 minutes · Artifact: labs/07-refactor/

Task 1. Dependency map (25 min)

Pick a function/class you want to replace. Build a map:

grep -rn "old_name" --include=*.py .

Fill in a table:

Acceptance: the map is complete (cross-check with grep once more), risks are ranked.

Task 2. Migration plan (25 min)

Write a 5–7 step plan, where each step:

• touches ≤ 2 files;
• ends with ./scripts/check.sh;
• has its own commit.

Acceptance: the plan was approved by you before starting work (record it in the report).

Task 3. Step-by-step migration (90 min)

Execute the steps according to the plan. After each one:

./scripts/check.sh
git add -A && git commit -m "step N: <what was done>"

Rules for the agent:

We work one plan step at a time. After the step, stop and show the diff.
Don't touch files outside <path>. Don't change public signatures.

Acceptance: at least 3 steps, each with green tests and a commit. In the report — git log --oneline and git diff --stat for the whole migration.

Task 4. Rollback test (25 min)

Break one step on purpose (tell the agent: "try doing step 4 together with step 5 right away"). Look at how many files were touched and how many tests failed. Roll back:

git reset --hard HEAD~1

Acceptance: in the report — a comparison of "one at a time" vs "all at once": number of files, number of failures, time spent untangling.

Task 5. Removing dead code (45 min)

After the migration:

The old code is no longer used. Find all references to <old_name>,
delete them and the code itself. If something still uses it — stop and show me the list.

Acceptance: tests green, grep for the old name is empty, diff reviewed.

Submission criteria

• The dependency map is complete.
• A plan with 5+ steps, approved before work.
• ≥ 3 steps with green tests and commits.
• The "all at once" experiment + rollback.
• Dead code removed, repository green.