Expand description
Test failure value.
Err fails the test (design-doc §0.6): Result for checks, panics for
testbench bugs (§7.3 failure taxonomy).
This lived in rustdv-runner until step 4. Component::run returns it
(D46/D47), and rustdv-methodology sits below the runner, so the type had to
move down. rustdv-runner re-exports it, and ::rustdv::TestError
resolves exactly as before.
The kind carries a machine-readable cause so a test can declare
#[rustdv::test(expect_error = "config_not_found")] and pass only if it
fails that way (D68). Without it the runner sees a flat string and
expect_fail accepts any failure at all — including a panic from
somewhere unrelated. pyuvm gets this from exception types
(expect_error=UVMConfigItemNotFound); rustdv errors are values, so the
cause travels as a field.