[Testing]: increase coverage to 80%

[jsjoeio]

Problem

We are unhappy with our current coverage (71% at the time of writing).

Solution

Write tests for code in the following files until we hit 80% coverage:

• entry.ts
• main.ts
• heart.ts
• http.ts
• util.ts

We don't know how many new tests but we do know that the following files previously listed are lacking in file coverage or close to hitting 100% based on Codecov stats.

The graph below shows files and lines missing code coverage based on running yarn test:unit in code-server:

[jsjoeio]

Closing in favor of #5149