If you have a coverage map you created yourself or got from some other
source, you can add it using this method. You probably don't need this. Use
addFromFile to create and store the coverage map for you.
This method takes a file path to a schema, generates a coverage map for it,
and stores it for later use. It returns the identifier for the schema
(usually the value of $id).
Retrieve a coverage map that was previously added through addFromFile or
addCoverageMap.
Get the file path for the schema that is identified by the given URI.
The
CoverageMapServicecreates istanbul coverage maps for your schemas and stores them for use by theTestCoverageEvaluationPlugin. A coverage map stores the file positions of all the keywords, schemas, and branches in a schema.