51720745dd
This commit adds the ability to change directories using the compiler's internal filesystem abstraction. This is a prerequisite for writing tests which are sensitive to the current working directory. In addition to supporting the `chdir()` operation, this commit also fixes `getDefaultLibLocation()` for mock filesystems to not assume `node_modules` is in the current directory, but to resolve it similarly to how Node does by progressively looking higher in the directory tree. PR Close #33828
Virtual file-system layer
To improve cross platform support, all file access (and path manipulation)
is now done through a well known interface (FileSystem).
For testing a number of MockFileSystem implementations are supplied.
These provide an in-memory file-system which emulates operating systems
like OS/X, Unix and Windows.
The current file system is always available via the helper method,
getFileSystem(). This is also used by a number of helper
methods to avoid having to pass FileSystem objects around all the time.
The result of this is that one must be careful to ensure that the file-system
has been initialized before using any of these helper methods.
To prevent this happening accidentally the current file system always starts out
as an instance of InvalidFileSystem, which will throw an error if any of its
methods are called.
You can set the current file-system by calling setFileSystem().
During testing you can call the helper function initMockFileSystem(os)
which takes a string name of the OS to emulate, and will also monkey-patch
aspects of the TypeScript library to ensure that TS is also using the
current file-system.
Finally there is the NgtscCompilerHost to be used for any TypeScript
compilation, which uses a given file-system.
All tests that interact with the file-system should be tested against each of the mock file-systems. A series of helpers have been provided to support such tests:
runInEachFileSystem()- wrap your tests in this helper to run all the wrapped tests in each of the mock file-systems, it callsinitMockFileSystem()for each OS to emulate.loadTestFiles()- use this to add files and their contents to the mock file system for testing.loadStandardTestFiles()- use this to load a mirror image of files on disk into the in-memory mock file-system.loadFakeCore()- use this to load a fake version of@angular/coreinto the mock file-system.
All ngcc and ngtsc source and tests now use this virtual file-system setup.