snapshot of https://github.com/marmelab/atomic-crm.git (main, 2026-09-18; blobs > 131072B omitted)

.claude/rules/testing.md

@@ -0,0 +1,79 @@
+---
+paths: []
+---
+
+# Testing
+
+## Minimum coverage: 80%
+
+New code paths without tests are a blocking issue in code review. But coverage is a
+FLOOR, not a target: never write a test just to reach the number (that is what produces
+filler tests). Pertinence outranks the percentage.
+
+## Pertinence: test behavior, not implementation
+
+- Assert user-observable behavior / rendered output (Testing Library principle: "the more
+  your tests resemble the way the software is used, the more confidence they give"). Never
+  assert internal state, props, private methods, or merely that a mock was called.
+- Weight toward integration for this React app (the Testing Trophy): a component with its
+  real collaborators over many shallow unit tests. Never test the framework or a third-party
+  library.
+- Delete a test ONLY for lack of intrinsic value (cannot name a realistic bug it would catch,
+  tautological, implementation-detail, snapshot-only, redundant with a better test), NEVER
+  because "the code works now" or to cap the count: a passing test exists to guard FUTURE
+  regressions. Shrink the suite by CONSOLIDATING redundancy, not by deleting coverage.
+- Forbidden (blocking in review): asserting a mock returns its configured value; a snapshot
+  as the primary assertion; reading component state / props / internals; a test written only
+  to raise the coverage number.
+
+## TDD orientation: acceptance-test-driven
+
+- Derive each test from the ticket's `acceptance_criteria`; every test should map to a
+  criterion or a user-visible behavior. A test with no traceable criterion is filler.
+- Enforce the OUTCOME (behavior tests present and green), not literal red-green ordering
+  (unverifiable when one agent writes both the test and the code).
+
+## Test structure — AAA pattern
+
+Prefer Arrange-Act-Assert for all tests:
+
+    test('calculates similarity correctly', () => {
+      // Arrange
+      const input = buildInput()
+
+      // Act
+      const result = compute(input)
+
+      // Assert
+      expect(result).toBe(expected)
+    })
+
+## Test naming
+
+Use descriptive names that explain the behavior under test:
+
+- returns empty array when no items match the query
+- throws error when required field is missing
+- falls back to default value when API is unavailable
+
+Avoid: test1, testFoo, should work.
+
+## Test isolation
+
+Each test must be independent — no shared mutable state.
+No test should depend on the execution order of other tests.
+Reset mocks and fixtures in beforeEach, not globally.
+
+## E2E shape (Playwright)
+
+    import { test, expect } from '@playwright/test'
+
+    test('ticket list loads', async ({ page }) => {
+      await page.goto('/tickets')
+      await expect(page.locator('h1')).toBeVisible()
+    })
+
+Never use timeout-based assertions (waitForTimeout).
+Always prefer deterministic waits: waitForResponse, waitForSelector,
+expect(locator).toBeVisible(). Flaky tests must be quarantined with
+test.fixme() and a tracking reference before merge.