7186f9c016
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 provided. 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 static method, `FileSystem.getFileSystem()`. This is also used by a number of static methods on `AbsoluteFsPath` and `PathSegment`, 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 static 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 `FileSystem.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. * `addTestFilesToFileSystem()` - use this to add files and their contents to the mock file system for testing. * `loadTestFilesFromDisk()` - 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/core` into the mock file-system. All ngcc and ngtsc source and tests now use this virtual file-system setup. PR Close #30921
43 lines
2.0 KiB
Markdown
43 lines
2.0 KiB
Markdown
# Virtual file-system layer
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To improve cross platform support, all file access (and path manipulation)
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is now done through a well known interface (`FileSystem`).
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For testing a number of `MockFileSystem` implementations are supplied.
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These provide an in-memory file-system which emulates operating systems
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like OS/X, Unix and Windows.
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The current file system is always available via the helper method,
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`getFileSystem()`. This is also used by a number of helper
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methods to avoid having to pass `FileSystem` objects around all the time.
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The result of this is that one must be careful to ensure that the file-system
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has been initialized before using any of these helper methods.
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To prevent this happening accidentally the current file system always starts out
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as an instance of `InvalidFileSystem`, which will throw an error if any of its
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methods are called.
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You can set the current file-system by calling `setFileSystem()`.
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During testing you can call the helper function `initMockFileSystem(os)`
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which takes a string name of the OS to emulate, and will also monkey-patch
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aspects of the TypeScript library to ensure that TS is also using the
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current file-system.
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Finally there is the `NgtscCompilerHost` to be used for any TypeScript
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compilation, which uses a given file-system.
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All tests that interact with the file-system should be tested against each
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of the mock file-systems. A series of helpers have been provided to support
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such tests:
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* `runInEachFileSystem()` - wrap your tests in this helper to run all the
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wrapped tests in each of the mock file-systems, it calls `initMockFileSystem()`
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for each OS to emulate.
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* `loadTestFiles()` - use this to add files and their contents
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to the mock file system for testing.
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* `loadStandardTestFiles()` - use this to load a mirror image of files on
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disk into the in-memory mock file-system.
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* `loadFakeCore()` - use this to load a fake version of `@angular/core`
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into the mock file-system.
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All ngcc and ngtsc source and tests now use this virtual file-system setup.
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