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في هذا الدرس

keep tests independent of each other.

الموضوعات المخطط لها

• Shared mutable data makes tests pass or fail depending on order.
• Options: roll back each test's transaction (@Transactional), clean tables in @BeforeEach, or use unique data per test.
• @Transactional on tests does not roll back when the code runs in another thread or via real HTTP.
• Prefer unique values (random email) so tests cannot collide.
• Never rely on rows left behind by other tests.