Fix runToFile not creating a file (#262)

core/src/main/scala/ox/flow/FlowIOOps.scala

@@ -65,11 +65,11 @@ trait FlowIOOps[+T]:
   def runToFile(path: Path)(using T <:< Chunk[Byte]): Unit =
     if Files.isDirectory(path) then throw new IOException(s"Path $path is a directory")
     val jFileChannel =
-      try FileChannel.open(path, StandardOpenOption.WRITE)
+      try FileChannel.open(path, StandardOpenOption.WRITE, StandardOpenOption.CREATE)
       catch
         case _: UnsupportedOperationException =>
           // Some file systems don't support file channels
-          Files.newByteChannel(path, StandardOpenOption.WRITE)
+          Files.newByteChannel(path, StandardOpenOption.WRITE, StandardOpenOption.CREATE)
 
     try
       runForeach(chunk => jFileChannel.write(ByteBuffer.wrap(chunk.toArray)).discard)

core/src/test/scala/ox/flow/FlowIOOpsTest.scala

@@ -95,22 +95,35 @@ class FlowIOOpsTest extends AnyWordSpec with Matchers:
 
   "toFile" should:
 
-    "create a file and write a single chunk with bytes" in supervised:
+    "open existing file and write a single chunk with bytes" in supervised:
       val path = useInScope(Files.createTempFile("ox", "test-writefile1"))(Files.deleteIfExists(_).discard)
       val sourceContent = "source.toFile test1 content"
       val source = Flow.fromValues(Chunk.fromArray(sourceContent.getBytes))
       source.runToFile(path)
 
       fileContent(path) shouldBe List(sourceContent)
 
-    "create a file and write multiple chunks with bytes" in supervised:
+    "open existing file and write multiple chunks with bytes" in supervised:
       val path = useInScope(Files.createTempFile("ox", "test-writefile2"))(Files.deleteIfExists(_).discard)
       val sourceContent = "source.toFile test2 content"
       val source = Flow.fromIterable(sourceContent.grouped(4).toList.map(chunkStr => Chunk.fromArray(chunkStr.getBytes)))
       source.runToFile(path)
 
       fileContent(path) shouldBe List(sourceContent)
 
+    "create file and write multiple chunks with bytes" in supervised:
+      var filePath = null: Path
+      val folderPath = useInScope(Files.createTempDirectory("ox")) { path =>
+        Files.deleteIfExists(filePath)
+        Files.deleteIfExists(path).discard
+      }
+      val sourceContent = "source.toFile test3 content"
+      filePath = folderPath.resolve("test-writefile3")
+      Flow.fromIterable(sourceContent.grouped(4).toList.map(chunkStr => Chunk.fromArray(chunkStr.getBytes)))
+        .runToFile(filePath)
+
+      fileContent(filePath) shouldBe List(sourceContent)
+
     "use an existing file and overwrite it a single chunk with bytes" in supervised:
       val path = useInScope(Files.createTempFile("ox", "test-writefile3"))(Files.deleteIfExists(_).discard)
       Files.write(path, "Some initial content".getBytes)
@@ -142,7 +155,7 @@ class FlowIOOpsTest extends AnyWordSpec with Matchers:
       exception.getMessage should endWith("is a directory")
 
     "throw an exception if file cannot be opened" in:
-      val path = Paths.get("/").resolve("/not-existing-directory/not-existing-file.txt")
+      val path = Paths.get("/").resolve("/directory-without-permissions/file-without-access.txt")
       val source = Flow.fromValues(Chunk.empty[Byte])
       assertThrows[NoSuchFileException](source.runToFile(path))