Contract Testing: Pact and the Pact Broker - Executable Tutorial Proposal

contributions/executable-tutorial/ganju-yasmines/README.md

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+# Assignment Proposal
+
+## Title
+
+Contract Testing: Pact and the Pact Broker
+
+## Names and KTH ID
+
+- Alexandru Gânju (ganju@kth.se)
+- Yasmine Schüllerqvist (yasmines@kth.se)
+
+## Deadline
+
+- Task 1
+
+## Category
+
+- Executable tutorial
+
+## Description
+
+We will create an executable Killercoda tutorial on contract testing between microservices
+with Pact. Everything runs in Docker (two Python services, the Pact Broker and its database),
+with a Git hook standing in for CI, so no accounts are needed.
+
+A user service renames a JSON field: its own tests pass, but the order service that depends
+on it breaks. The learner writes a consumer contract with Pact (using type matchers so the
+provider can still evolve), verifies the real provider against it using provider states, and
+publishes the results to the Pact Broker. They then verify two consumer versions against three
+provider versions and explore the resulting compatibility matrix. Starting from what is
+recorded as deployed in production, they use `can-i-deploy` to discover that the rename can
+only be released safely in three steps (expand, migrate, contract), with a Git pre-push hook
+blocking unsafe deployments. Each step has an automated check, and the tutorial ends with a
+reflection on when contract testing is worth it and its limits.
+
+**Intended learning outcomes.** The learner can explain why separate test suites miss
+breaking API changes, write and verify a Pact contract, read the compatibility matrix, and
+use `can-i-deploy` to decide a safe deployment order.
+
+**Relevance**
+Contract testing lets teams deploy services independently: API
+compatibility is checked in seconds in CI instead of in slow end-to-end environments, and
+`can-i-deploy` acts as an automated deployment gate.
+