From 2626a3c18dc8a790dc824967d110b31c86a4f4cf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Zaja=CC=A8c?= <zajac.mateusz@icloud.com>
Date: Mon, 29 May 2017 17:02:55 +0200
Subject: [PATCH] Method for creaating file if needed from FileSystem

---
 Sources/Files.swift               | 18 ++++++++++++++++++
 Tests/FilesTests/FilesTests.swift | 13 +++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/Sources/Files.swift b/Sources/Files.swift
index ed2fb8c..c2b7133 100644
--- a/Sources/Files.swift
+++ b/Sources/Files.swift
@@ -326,6 +326,24 @@ public class FileSystem {
         }
     }
 
+    /**
+     *  Either return an existing file, or create a new one, at a given path.
+     *
+     *  - parameter path: The path for which a file should either be returned or created at. If the folder
+     *                    is missing, any intermediate parent folders will also be created.
+     *
+     *  - throws: `File.Error.writeFailed`
+     *
+     *  - returns: The file that was either created or found.
+     */
+    @discardableResult public func createFileIfNeeded(at path: String, contents: Data = Data()) throws -> File {
+        if let existingFile = try? File(path: path, using: fileManager) {
+            return existingFile
+        }
+
+        return try createFile(at: path, contents: contents)
+    }
+
     /**
      *  Create a new folder at a given path
      *
diff --git a/Tests/FilesTests/FilesTests.swift b/Tests/FilesTests/FilesTests.swift
index 0b7a183..04af624 100644
--- a/Tests/FilesTests/FilesTests.swift
+++ b/Tests/FilesTests/FilesTests.swift
@@ -459,6 +459,19 @@ class FilesTests: XCTestCase {
         }
     }
 
+    func testCreateFileFromFileSystemIfNeeded() {
+        performTest {
+            let path = folder.path + "one/two/three/file"
+            let contentA = "Hello".data(using: .utf8)!
+            let contentB = "World".data(using: .utf8)!
+            let fileA = try FileSystem().createFileIfNeeded(at: path, contents: contentA)
+            let fileB = try FileSystem().createFileIfNeeded(at: path, contents: contentB)
+
+            try XCTAssertEqual(fileA.readAsString(), "Hello")
+            try XCTAssertEqual(fileA.read(), fileB.read())
+        }
+    }
+
     func testCreatingFolderFromFileSystem() {
         performTest {
             let folderPath = folder.path + "one/two/three"