| name | pharo-tdd |
| description | Drive a Genie change test-first through the genie MCP tools, working entirely from the live image (no files). Use when adding behavior or fixing a bug in the image — anything where a test should lead. |
Pharo TDD loop (live image, via the genie MCP tools)
All work goes through the genie MCP tools — there are no files. Read with the
read tools, change only via define_class / define_method / eval. Confirm
every change by reading it back. Never assume a class/selector exists — look it
up first.
Loop
-
Locate. Find the class and its test class:
list_classes (package) → list_methods → get_method_source.
Find the matching ...Test (TestCase subclass). If none exists, create it
via define_class (superclass TestCase).
-
Red. Write or adjust ONE failing test with define_method (protocol
tests). Run it: run_test with class_name. Expect failure. If it
passes immediately, the test isn't exercising the new behavior — fix the
test before writing code.
-
Green. Implement the smallest method that could pass, via
define_method. Run run_test again → expect green. Read the method back
with get_method_source to confirm what's installed.
-
Regression check. Run run_test for the whole package_name. A green
class test with a red package is not done.
-
Refactor. Clean up while green, re-running run_test after each step.
(For larger cleanups, switch to the pharo-refactor skill.)
-
Done. Persist with save_image gated on tests — pass test_package so
it runs them and saves the image only if green. Summarize what changed
(class >> selector list).
Debugging a red test
Genie returns full stack traces: failing block source, receiver, and its
variables. Read them. Reproduce the failure with a minimal eval first, fix
the smallest thing the trace implicates, then re-run the test. Don't guess.
Rules
- One test, one reason to fail, at a time.
- Modern class API only (
ShiftClassInstaller / define_class), never the
deprecated subclass:instanceVariableNames:classVariableNames:package:.
- Tests are methods too — install them with
define_method, protocol tests.