fake_core is a library designed to expose some of the same symbols as @angular/core, without
requiring compilation of the whole of @angular/core. This enables unit tests for the compiler to
be written without incurring long rebuilds for every change.
@angular/coreis compiled with@angular/compiler-cli, and therefore has an implicit dependency on it. Therefore core must be rebuilt if the compiler changes.- Tests for the compiler which intend to build code that depends on
@angular/coremust have a data dependency on@angular/core. Therefore core must be built to run the compiler tests, and thus rebuilt if the compiler changes.
This rebuild cycle is expensive and slow. fake_core avoids this by exposing a subset of the
@angular/core API, which enables applications to be built by the ngtsc compiler without
needing a full version of core present at compile time.