### What problem does this PR solve?
Test cases about dataset
### Type of change
- [x] Other (please describe): test cases
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Signed-off-by: jinhai <haijin.chn@gmail.com>
### What problem does this PR solve?
1. Remove unused code.
2. Move some codes from settings to constants
### Type of change
- [x] Refactoring
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Signed-off-by: jinhai <haijin.chn@gmail.com>