syncmap: make quick-check output more readable

Add a test for Range with concurrent Loads and Stores.

The previous quick-check tests generated long, mostly-non-ASCII
strings that were hard to debug on failure; this change makes the keys
and values short and human-readable, which also tends to produce more
key collisions in the test as a side-effect.

updates golang/go#18177

Change-Id: Ie56a64ec9fe295435682b90c3e6466ed5b349bf9
Reviewed-by: Russ Cox <>
1 file changed