Tests the checker against its own test suite.
Compiles the checker, creates test files, runs all tests, and cleans up.
This is a cancellation point - fails fast on first error.
Returns Promise<void>
Throws
If checker tests fail
Throws
If checker compilation fails
Throws
If test file parsing fails
Example
// From actions.ts testWhat command awaittestCheckerItself();
Tests the checker against its own test suite. Compiles the checker, creates test files, runs all tests, and cleans up. This is a cancellation point - fails fast on first error.