In usual configuration there are two files, tsconfig.app.json and tsconfig.spec.jcon and while developing it is handy to see errors/warning both for spec and app at the same time.
However, it is possible to specify only one file in IDE.
Current workaround is to create tscofig.ide.spec that extends tsconfig.app.json and overrides exclude, so spec files are compiled too. It works ok.
However, app.json and spec.json can be have different conflicting values and it is not always possible to derive a common configuration for both spec and app, either we compile with spec settings or with app settings (or something in between by patching in ide).
IDE should allow specifying multiple TS configuration files and compiling with them in parallel.