AAA & Test Naming

AAA and tests that read like specs

Every good test has three blocks, visibly separated:

// Arrange — build the world
var cart = new Cart();
cart.add(new Item("pen", 200));

// Act — one behavior
int total = cart.totalCents();

// Assert — one expectation
assertEquals(200, total);

Discipline that scales:

• One behavior per test — two asserts of the same behavior are fine; two behaviors are not
• Name = scenario + expectation: total_includes_quantity_multiplier, not testTotal
• No logic in tests (no loops, no ifs) — if you need logic, you're re-implementing the subject under test
• Tests are the first reader of your API: if arranging is painful, the API needs a builder or factory

A failing test message should tell you what broke without opening a debugger — that's why checkEq(actual, expected, "what") takes a label.