A report no longer throws, so a noexcept mock survives an aborting run.
A call that has nothing to return still leaves the test case, which ends
the process in a noexcept function; the documentation says so.

RunContext clears the result capture when it goes, so a mock of static
lifetime finds none and writes to standard error.

Decision owns its source line, since Verify can free the expectation
while a call is on its way. Moving a result out takes the lock. Vector
matchers refer to their vector, so they are rejected at compile time
like composed ones. A null text expectation accepts only null, and
integers compare by value, so 256 no longer accepts an unsigned char.

A static mutex needs an exit-time destructor, which Clang's warnings
refuse, and a mock of static lifetime can outlive it. The test seam is
held the same way, and a test covers a mock method with nothing after
its parameters, which needs an empty variadic argument to stay valid
under -Wpedantic.

Step 3 of the roadmap. MockFunction checks the calls of one function
against its expectations; CATCH3_MOCK_METHOD declares one for a virtual
member, and CATCH3_MOCK_FUNCTION and ScopedSeam serve free functions
behind a seam.

Expectations take values, Catch matchers, Any or Where; count calls with
Times, Between, AtLeast, AtMost, AnyTimes and Never; answer with Returns,
Does or Throws; and order calls across mocks with Sequence. A failure
goes through AssertionHandler at the line of the expectation, so every
report of the runner shows it. Met expectations count as passed
assertions. A test case that is already being left does not get unmet
expectations on top of its own failure.

Composed matchers refer to temporaries, so they are rejected at compile
time rather than left dangling. A call that fails returns a
value-initialized result, or leaves the test case when no such result
exists.

The failure paths are tested through the runner fixture, reading the
messages from its JSON report.