std.test

std.test: what fb test runs and checks with. A @Test Function, one that takes nothing and gives nothing back, though it can throw, is a test, anywhere in a package, and so is one in its tests/ folder, which uses the package from outside. Builds leave tests out, and fb test runs them, in parallel, on the runtime's pool, but for those whose code uses what only the main thread can. Work a test starts on another thread is the test's, wherever it runs.

Its names are the compiler's own, which a file has with Import std.test, not From or As:

• Expect(condition) and Expect(condition, message): when the condition is False, the test fails, saying what it checked and where, and for a comparison, like Expect(a == b), each side's debug form, then goes on.
• ExpectThrows(x) and ExpectThrows<E>(x): what x throws, which it catches, as Try? would, as an Error? or an E?; when x throws nothing, or nothing that's an E, the test fails, and it gives Null.
• Fail() and Fail(message): the test fails, and goes on.
• Skip() and Skip(reason): the test is skipped, and ends there, as a Return would.

A panic, as a failed Assert's, fails its test, and fb test runs the ones it didn't finish again, and in a debug build, the ones that finished in that run too, whose leaks it didn't check.