... e.g.
```
  // Allocate a chunk; it must succeed. Test the chunk.
  void alloc_chunk_expect_success(Metachunk** p_return_value, chunklevel_t preferred_level, chunklevel_t max_level, size_t min_committed_size) {
    checked_alloc_chunk_0(p_return_value, preferred_level, max_level, min_committed_size);
    ASSERT_NOT_NULL(*p_return_value);
  }
```

which demonstrates a misunderstanding on my part of how ASSERT_xxx works :-/

ASSERT_xxx *abort the current function*, so doing it inside a sub function just aborts the sub function, but will continue the test.