Testing io/fs Implementations

io/fs is getting closer and closer. The functionality is great, but how do we test it? There is a function in testing/fstest that can do just that.

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package fstest

// TestFS tests a file system implementation.
// It walks the entire tree of files in fsys,
// opening and checking that each file behaves correctly.
// It also checks that the file system contains at least the expected files.
// As a special case, if no expected files are listed, fsys must be empty.
// Otherwise, fsys must only contain at least the listed files: it can also contain others.
//
// If TestFS finds any misbehaviors, it returns an error reporting all of them.
// The error text spans multiple lines, one per detected misbehavior.
//
// Typical usage inside a test is:
//
//	if err := fstest.TestFS(myFS, "file/that/should/be/present"); err != nil {
//		t.Fatal(err)
//	}
//
func TestFS(fsys fs.FS, expected ...string) error

io/fs 越来越近了功能很好但我们怎么才能测试它呢？testing/fstest 中有一个函数可以做到这件事情。

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package fstest

// TestFS tests a file system implementation.
// It walks the entire tree of files in fsys,
// opening and checking that each file behaves correctly.
// It also checks that the file system contains at least the expected files.
// As a special case, if no expected files are listed, fsys must be empty.
// Otherwise, fsys must only contain at least the listed files: it can also contain others.
//
// If TestFS finds any misbehaviors, it returns an error reporting all of them.
// The error text spans multiple lines, one per detected misbehavior.
//
// Typical usage inside a test is:
//
//	if err := fstest.TestFS(myFS, "file/that/should/be/present"); err != nil {
//		t.Fatal(err)
//	}
//
func TestFS(fsys fs.FS, expected ...string) error