Please write more details.

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Normally for software development, for each task, testers create test case before test execution. once test executed, update the test case with actual result . if there are some bugs they can also create bug report that can be linked to new issues. I feel that this particular part of SDLC is missing in Redmine. there may be difference for the format of test case template but if you can implement a customization process for the same will be an added advantage.
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Manoj,

I think you should look at Test-Case Management software:
[[ThirdPartyTools#Test-Case-Management|ThirdPartyTools - Test-Case-Management]]

Those software packages allow you to create testcases, and then link them to Redmine issues.
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