Note: npm run test still prints clean and neat output. Generally you should run npm run ci in your CI tool. Keep the ouptut clean and neat for npm run test is good for running test cases in your local machine.
Why and How
TeamCity is a advanced CI tool that can display and analyze the coverage and tests for you. You can check out the details of test coverage and test cases for each build. Futher you can see the trend of them if you concern the codebase quality.
To do that you have to tell TeamCity how to detect those information from build log. There are reporters call teamcity reporters that print cov. and test cases information in a certain partern that TeamCity knows. It looks like: