As per described on JRA-31882, I've performed the same tests using dash ('-') instead of underscore ('_'), and the results were the same when using "test-1234".

However, upon testing a bit further, it seems JIRA is not being able to find results when searching using wildcard and dash twice in a row, if the first two parts only contain letters (e.g.: "TEST-ABCD-JI*").

Steps to reproduce:

1. Create an issue with the summary "TEST-ABCD-JIRA" and one "TEST-ABC1D-JIRA";
2. Open the JQL;
3. Search for

   Summary ~ "TEST-ABCD-JI*"

   and

   Summary ~ "TEST-ABC1D-JI*"

Expected Results:

When searching for Summary ~ "TEST-ABCD-JI*", JIRA would find the issue with summary "TEST-ABCD-JIRA"; and when searching for "TEST-ABC1D-JI*" JIRA would find "TEST-ABC1D-JIRA".

Actual Results:

When searching for Summary ~ "TEST-ABCD-JI*", JIRA does not find the issue with summary "TEST-ABCD-JIRA"; but when searching for "TEST-ABC1D-JI*" JIRA finds "TEST-ABC1D-JIRA".

Notes:
This was tested in JIRA 5.2.11 using 'Other' as the Indexing Language.
There are two problems described in this report. Inconsistent behavior with contains operator when searching using the dash character (which may be covered in JRA-31882 if updated), and the search not finding results if having multiple dashes and only characters.