Add 'withTemporaryDirectory' (#2708)

Motivation:

NIOFileSystem can create the path of a temporary directory but doesn't
offer any API to create and then remove a directory.

Modifications:

- Add `withTemporaryDirectory`

Result:

- Users can get scoped access to a temporary directory which is
  subsequently removed for them
- Resolves #2664

Sources/NIOFileSystem/Docs.docc/Extensions/FileSystemProtocol.md

@@ -43,3 +43,4 @@ closing it to avoid leaking resources.
 
 - ``currentWorkingDirectory``
 - ``temporaryDirectory``
+- ``withTemporaryDirectory(prefix:options:execute:)``

Sources/NIOFileSystem/FileSystemProtocol.swift

@@ -476,6 +476,42 @@ extension FileSystemProtocol {
  permissions: .defaultsForDirectory
  )
  }
+
+ /// Create a temporary directory and removes it once the function returns.
+ ///
+ /// You can use `prefix` to specify the directory in which the temporary directory should
+ /// be created. If `prefix` is `nil` then the value of ``temporaryDirectory`` is used as
+ /// the prefix.
+ ///
+ /// The temporary directory, and all of its contents, is removed once `execute` returns.
+ ///
+ /// - Parameters:
+ /// - prefix: The prefix to use for the path of the temporary directory.
+ /// - options: Options used to create the directory.
+ /// - execute: A closure which provides access to the directory and its path.
+ /// - Returns: The result of `execute`.
+ public func withTemporaryDirectory<ReturnType>(
+ prefix: FilePath? = nil,
+ options: OpenOptions.Directory = OpenOptions.Directory(),
+ execute: (_ directory: DirectoryFileHandle, _ path: FilePath) async throws -> ReturnType
+ ) async throws -> ReturnType {
+ let template: FilePath
+
+ if let prefix = prefix {
+ template = prefix.appending("XXXXXXXX")
+ } else {
+ template = try await self.temporaryDirectory.appending("XXXXXXXX")
+ }
+
+ let directory = try await self.createTemporaryDirectory(template: template)
+ return try await withUncancellableTearDown {
+ try await withDirectoryHandle(atPath: directory, options: options) { handle in
+ try await execute(handle, directory)
+ }
+ } tearDown: { _ in
+ try await self.removeItem(at: directory, recursively: true)
+ }
+ }
 }
 
 #endif

Tests/NIOFileSystemIntegrationTests/FileSystemTests.swift

@@ -1055,6 +1055,55 @@ final class FileSystemTests: XCTestCase {
  XCTAssertEqual(names.sorted(), expected.sorted())
  }
  }
+
+ func testWithTemporaryDirectory() async throws {
+ let fs = FileSystem.shared
+
+ let createdPath = try await fs.withTemporaryDirectory { directory, path in
+ let root = try await fs.temporaryDirectory
+ XCTAssert(path.starts(with: root))
+ return path
+ }
+
+ // Directory shouldn't exist any more.
+ let info = try await fs.info(forFileAt: createdPath)
+ XCTAssertNil(info)
+ }
+
+ func testWithTemporaryDirectoryPrefix() async throws {
+ let fs = FileSystem.shared
+ let prefix = try await fs.currentWorkingDirectory
+
+ let createdPath = try await fs.withTemporaryDirectory(prefix: prefix) { directory, path in
+ XCTAssert(path.starts(with: prefix))
+ return path
+ }
+
+ // Directory shouldn't exist any more.
+ let info = try await fs.info(forFileAt: createdPath)
+ XCTAssertNil(info)
+ }
+
+ func testWithTemporaryDirectoryRemovesContents() async throws {
+ let fs = FileSystem.shared
+ let createdPath = try await fs.withTemporaryDirectory { directory, path in
+ for name in ["foo", "bar", "baz"] {
+ try await directory.withFileHandle(forWritingAt: FilePath(name)) { fh in
+ _ = try await fh.write(contentsOf: [1, 2, 3], toAbsoluteOffset: 0)
+ }
+ }
+
+ let entries = try await directory.listContents().reduce(into: []) { $0.append($1) }
+ let names = entries.map { $0.name.string }
+ XCTAssertEqual(names.sorted(), ["bar", "baz", "foo"])
+
+ return path
+ }
+
+ // Directory shouldn't exist any more.
+ let info = try await fs.info(forFileAt: createdPath)
+ XCTAssertNil(info)
+ }
 }
 
 @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)