Test and Documentation Enhancement

[zhiwei2017]

Enhancements:

1. remove irrelevant badge
2. add badge for sonarcloud
3. fix issues in tests found by sonarcloud

[codecov-commenter]

Codecov Report

Merging #65 into dev will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##               dev       #65   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            1         1           
  Lines          167       167           
=========================================
  Hits           167       167           

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[sonarcloud]

Kudos, SonarCloud Quality Gate passed!

0 Bugs
0 Vulnerabilities (and 0 Security Hotspots to review)
0 Code Smells

No Coverage information
No Duplication information