TSCover is a Typescript compiler that produces instrumented javascript used to collect code coverage information. Code coverage is saved in the form of LCOV files, JSON files or as an HTML report.

• Works as a drop-in replacement for tsc. All tsc options work as expected.
• Instruments .ts files during compilation. Does not require .map files.
• Reports coverage as lcov.info, json files or as an html report.
• Supports statement, branch and file coverage.

TSCover requires typescript library so first step is to make sure that typescript is installed globally. After that install tscover as the global library:

npm install -g typescript
npm install -g tscover

You can run tscover the same way that you would run tsc, all tsc options will work as expected. Or you can use tsconfig.json to specify compiler options:

tscover program.ts
tscover -p project/tsconfig.json

Run the program as you normally would and upon exit it will produce a coverage folder with lcov, json and html files in it.

Normally tscover produces compiled javascript files only. However if you would like to see instrumented typescript files too pass --tscover-instrument flag:

tscover --tscover-instrument -p project/tsconfig.json

This will instruct the compiler to produce .ts.cover files that can be used for troubleshooting.