Add test

[phungquanghuy]

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What kind of change does this PR introduce? (check at least one)

• [ ] Bugfix
• [ ] Feature
• [ ] Code style update
• [ ] Refactor
• [ ] Build-related changes
• [x] Other, please describe: Add test case for TowSumTest.java

The description of the PR:

Other information:

[phungquanghuy]

Wrong