test: refactor tests for CLI

[aj3sh]

Description

Refactor tests for CLI:

• Mocked sys.args instead of mocking parse_args.

Related Issue

N/A

Type of Change

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• Bug fix
• New feature
• Enhancement
• Documentation update
• Refactor
• Other (please specify)

Checklist

• My pull request has a clear title and description.
• I have used semantic commit messages.
  Examples: "fix: Fixed foobar bug", "feat(accounts): Added foobar feature".
• I have added/updated the necessary documentation on README.md.
• I have added appropriate test cases (if applicable) to ensure the changes are functioning correctly.

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