feat: add ISO direct download from URL to JetKVM storage

Add feature to download ISO/IMG files directly to JetKVM storage from a
URL. This addresses the use case where remote deployments have slow
upload speeds, making direct URL downloads significantly faster.

Backend changes:
- Add DownloadState struct for tracking download progress
- Add rpcDownloadFromUrl, rpcGetDownloadState, rpcCancelDownload RPCs
- Implement streaming download with 32KB buffer and progress tracking
- Broadcast download state events to connected clients

Frontend changes:
- Add DownloadFileView component with URL input and progress display
- Add "Download from URL" button in Device Storage view
- Auto-extract filename from URL for .iso/.img files
- Poll-based progress updates with speed calculation
- Support for download cancellation

Fixes #727

jsonrpc.go

@@ -1181,6 +1181,9 @@ var rpcHandlers = map[string]RPCHandler{
 	"listStorageFiles":       {Func: rpcListStorageFiles},
 	"deleteStorageFile":      {Func: rpcDeleteStorageFile, Params: []string{"filename"}},
 	"startStorageFileUpload": {Func: rpcStartStorageFileUpload, Params: []string{"filename", "size"}},
+	"downloadFromUrl":        {Func: rpcDownloadFromUrl, Params: []string{"url", "filename"}},
+	"getDownloadState":       {Func: rpcGetDownloadState},
+	"cancelDownload":         {Func: rpcCancelDownload},
 	"getWakeOnLanDevices":    {Func: rpcGetWakeOnLanDevices},
 	"setWakeOnLanDevices":    {Func: rpcSetWakeOnLanDevices, Params: []string{"params"}},
 	"resetConfig":            {Func: rpcResetConfig},

ui/localization/messages/en.json

@@ -568,6 +568,19 @@
     "mount_uploaded_has_been_uploaded": "{name} has been uploaded",
     "mount_uploading": "Uploading…",
     "mount_uploading_with_name": "Uploading {name}",
+    "mount_download_title": "Download from URL",
+    "mount_download_description": "Download an image file directly to JetKVM storage from a URL",
+    "mount_download_url_label": "Image URL",
+    "mount_download_filename_label": "Save as filename",
+    "mount_downloading": "Downloading...",
+    "mount_downloading_with_name": "Downloading {name}",
+    "mount_download_successful": "Download successful",
+    "mount_download_has_been_downloaded": "{name} has been downloaded",
+    "mount_download_error": "Download error: {error}",
+    "mount_download_cancelled": "Download cancelled",
+    "mount_button_start_download": "Start Download",
+    "mount_button_cancel_download": "Cancel Download",
+    "mount_button_download_from_url": "Download from URL",
     "mount_url_description": "Mount files from any public web address",
     "mount_url_input_label": "Image URL",
     "mount_url_mount": "URL Mount",

ui/src/hooks/stores.ts

@@ -443,7 +443,7 @@ export interface MountMediaState {
   remoteVirtualMediaState: RemoteVirtualMediaState | null;
   setRemoteVirtualMediaState: (state: MountMediaState["remoteVirtualMediaState"]) => void;
 
-  modalView: "mode" | "url" | "device" | "upload" | "error" | null;
+  modalView: "mode" | "url" | "device" | "upload" | "download" | "error" | null;
   setModalView: (view: MountMediaState["modalView"]) => void;
 
   isMountMediaDialogOpen: boolean;

ui/src/routes/devices.$id.mount.tsx

@@ -5,6 +5,7 @@ import {
   LuRadioReceiver,
   LuCheck,
   LuUpload,
+  LuDownload,
 } from "react-icons/lu";
 import { PlusCircleIcon, ExclamationTriangleIcon } from "@heroicons/react/20/solid";
 import { TrashIcon } from "@heroicons/react/16/solid";
@@ -186,6 +187,9 @@ export function Dialog({ onClose }: Readonly<{ onClose: () => void }>) {
                     setIncompleteFileName(incompleteFile || null);
                     setModalView("upload");
                   }}
+                  onDownloadClick={() => {
+                    setModalView("download");
+                  }}
                 />
               )}
 
@@ -200,6 +204,15 @@ export function Dialog({ onClose }: Readonly<{ onClose: () => void }>) {
                 />
               )}
 
+              {modalView === "download" && (
+                <DownloadFileView
+                  onBack={() => setModalView("device")}
+                  onDownloadComplete={() => {
+                    setModalView("device");
+                  }}
+                />
+              )}
+
               {modalView === "error" && (
                 <ErrorView
                   errorMessage={errorMessage}
@@ -508,11 +521,13 @@ function DeviceFileView({
   mountInProgress,
   onBack,
   onNewImageClick,
+  onDownloadClick,
 }: {
   onMountStorageFile: (name: string, mode: RemoteVirtualMediaState["mode"]) => void;
   mountInProgress: boolean;
   onBack: () => void;
   onNewImageClick: (incompleteFileName?: string) => void;
+  onDownloadClick: () => void;
 }) {
   const [onStorageFiles, setOnStorageFiles] = useState<
     {
@@ -799,7 +814,7 @@ function DeviceFileView({
 
       {onStorageFiles.length > 0 && (
         <div
-          className="w-full animate-fadeIn opacity-0"
+          className="w-full animate-fadeIn space-y-2 opacity-0"
           style={{
             animationDuration: "0.7s",
             animationDelay: "0.25s",
@@ -812,6 +827,13 @@ function DeviceFileView({
             text={m.mount_button_upload_new_image()}
             onClick={() => onNewImageClick()}
           />
+          <Button
+            size="MD"
+            theme="light"
+            fullWidth
+            text={m.mount_button_download_from_url()}
+            onClick={() => onDownloadClick()}
+          />
         </div>
       )}
     </div>
@@ -1247,6 +1269,272 @@ function UploadFileView({
   );
 }
 
+function DownloadFileView({
+  onBack,
+  onDownloadComplete,
+}: {
+  onBack: () => void;
+  onDownloadComplete: () => void;
+}) {
+  const [downloadViewState, setDownloadViewState] = useState<"idle" | "downloading" | "success" | "error">("idle");
+  const [url, setUrl] = useState<string>("");
+  const [filename, setFilename] = useState<string>("");
+  const [progress, setProgress] = useState(0);
+  const [downloadSpeed, setDownloadSpeed] = useState<number | null>(null);
+  const [downloadError, setDownloadError] = useState<string | null>(null);
+  const [totalBytes, setTotalBytes] = useState<number>(0);
+
+  const { send } = useJsonRpc();
+
+  // Track download speed
+  const lastBytesRef = useRef(0);
+  const lastTimeRef = useRef(0);
+  const speedHistoryRef = useRef<number[]>([]);
+
+  // Compute URL validity
+  const isUrlValid = useMemo(() => {
+    try {
+      const urlObj = new URL(url);
+      return urlObj.protocol === 'http:' || urlObj.protocol === 'https:';
+    } catch {
+      return false;
+    }
+  }, [url]);
+
+  // Extract filename from URL
+  const suggestedFilename = useMemo(() => {
+    if (!url) return '';
+    try {
+      const urlObj = new URL(url);
+      const pathParts = urlObj.pathname.split('/');
+      const lastPart = pathParts[pathParts.length - 1];
+      if (lastPart && (lastPart.endsWith('.iso') || lastPart.endsWith('.img'))) {
+        return lastPart;
+      }
+    } catch {
+      // Invalid URL, ignore
+    }
+    return '';
+  }, [url]);
+
+  // Update filename when URL changes and user hasn't manually edited it
+  const [userEditedFilename, setUserEditedFilename] = useState(false);
+  const effectiveFilename = userEditedFilename ? filename : (suggestedFilename || filename);
+
+  // Listen for download state events via polling
+  useEffect(() => {
+    if (downloadViewState !== "downloading") return;
+
+    const pollInterval = setInterval(() => {
+      send("getDownloadState", {}, (resp: JsonRpcResponse) => {
+        if ("error" in resp) return;
+
+        const state = resp.result as {
+          downloading: boolean;
+          filename: string;
+          totalBytes: number;
+          doneBytes: number;
+          progress: number;
+          error?: string;
+        };
+
+        if (state.error) {
+          setDownloadError(state.error);
+          setDownloadViewState("error");
+          return;
+        }
+
+        setTotalBytes(state.totalBytes);
+        setProgress(state.progress * 100);
+
+        // Calculate speed
+        const now = Date.now();
+        const timeDiff = (now - lastTimeRef.current) / 1000;
+        const bytesDiff = state.doneBytes - lastBytesRef.current;
+
+        if (timeDiff > 0 && bytesDiff > 0) {
+          const instantSpeed = bytesDiff / timeDiff;
+          speedHistoryRef.current.push(instantSpeed);
+          if (speedHistoryRef.current.length > 5) {
+            speedHistoryRef.current.shift();
+          }
+          const avgSpeed = speedHistoryRef.current.reduce((a, b) => a + b, 0) / speedHistoryRef.current.length;
+          setDownloadSpeed(avgSpeed);
+        }
+
+        lastBytesRef.current = state.doneBytes;
+        lastTimeRef.current = now;
+
+        if (!state.downloading && state.progress >= 1) {
+          setDownloadViewState("success");
+        }
+      });
+    }, 500);
+
+    return () => clearInterval(pollInterval);
+  }, [downloadViewState, send]);
+
+  function handleStartDownload() {
+    if (!url || !effectiveFilename) return;
+
+    setDownloadViewState("downloading");
+    setDownloadError(null);
+    setProgress(0);
+    setDownloadSpeed(null);
+    lastBytesRef.current = 0;
+    lastTimeRef.current = Date.now();
+    speedHistoryRef.current = [];
+
+    send("downloadFromUrl", { url, filename: effectiveFilename }, (resp: JsonRpcResponse) => {
+      if ("error" in resp) {
+        setDownloadError(resp.error.message);
+        setDownloadViewState("error");
+      }
+    });
+  }
+
+  function handleCancelDownload() {
+    send("cancelDownload", {}, (resp: JsonRpcResponse) => {
+      if ("error" in resp) {
+        console.error("Failed to cancel download:", resp.error);
+      }
+      setDownloadViewState("idle");
+    });
+  }
+
+  return (
+    <div className="w-full space-y-4">
+      <ViewHeader
+        title={m.mount_download_title()}
+        description={m.mount_download_description()}
+      />
+
+      {downloadViewState === "idle" && (
+        <>
+          <div className="animate-fadeIn space-y-4 opacity-0" style={{ animationDuration: "0.7s" }}>
+            <InputFieldWithLabel
+              placeholder="https://example.com/image.iso"
+              type="url"
+              label={m.mount_download_url_label()}
+              value={url}
+              onChange={e => setUrl(e.target.value)}
+            />
+            <InputFieldWithLabel
+              placeholder="image.iso"
+              type="text"
+              label={m.mount_download_filename_label()}
+              value={effectiveFilename}
+              onChange={e => {
+                setFilename(e.target.value);
+                setUserEditedFilename(true);
+              }}
+            />
+          </div>
+          <div className="flex w-full justify-end space-x-2">
+            <Button size="MD" theme="blank" text={m.back()} onClick={onBack} />
+            <Button
+              size="MD"
+              theme="primary"
+              text={m.mount_button_start_download()}
+              onClick={handleStartDownload}
+              disabled={!isUrlValid || !effectiveFilename}
+            />
+          </div>
+        </>
+      )}
+
+      {downloadViewState === "downloading" && (
+        <div className="animate-fadeIn space-y-4 opacity-0" style={{ animationDuration: "0.7s" }}>
+          <Card>
+            <div className="p-4 space-y-3">
+              <div className="flex items-center gap-2">
+                <LuDownload className="h-5 w-5 text-blue-500 animate-pulse" />
+                <h3 className="text-lg font-semibold dark:text-white">
+                  {m.mount_downloading_with_name({ name: formatters.truncateMiddle(effectiveFilename, 30) })}
+                </h3>
+              </div>
+              <p className="text-sm text-slate-600 dark:text-slate-400">
+                {formatters.bytes(totalBytes)}
+              </p>
+              <div className="h-3.5 w-full overflow-hidden rounded-full bg-slate-300 dark:bg-slate-700">
+                <div
+                  className="h-3.5 rounded-full bg-blue-700 transition-all duration-500 ease-linear dark:bg-blue-500"
+                  style={{ width: `${progress}%` }}
+                />
+              </div>
+              <div className="flex justify-between text-xs text-slate-600 dark:text-slate-400">
+                <span>{m.mount_downloading()}</span>
+                <span>
+                  {downloadSpeed !== null
+                    ? `${formatters.bytes(downloadSpeed)}/s`
+                    : m.mount_calculating()}
+                </span>
+              </div>
+            </div>
+          </Card>
+          <div className="flex w-full justify-end">
+            <Button
+              size="MD"
+              theme="light"
+              text={m.mount_button_cancel_download()}
+              onClick={handleCancelDownload}
+            />
+          </div>
+        </div>
+      )}
+
+      {downloadViewState === "success" && (
+        <div className="animate-fadeIn space-y-4 opacity-0" style={{ animationDuration: "0.7s" }}>
+          <Card>
+            <div className="p-4 text-center space-y-2">
+              <LuCheck className="h-8 w-8 text-green-500 mx-auto" />
+              <h3 className="text-lg font-semibold dark:text-white">
+                {m.mount_download_successful()}
+              </h3>
+              <p className="text-sm text-slate-600 dark:text-slate-400">
+                {m.mount_download_has_been_downloaded({ name: effectiveFilename })}
+              </p>
+            </div>
+          </Card>
+          <div className="flex w-full justify-end">
+            <Button
+              size="MD"
+              theme="primary"
+              text={m.mount_button_back_to_overview()}
+              onClick={onDownloadComplete}
+            />
+          </div>
+        </div>
+      )}
+
+      {downloadViewState === "error" && (
+        <div className="animate-fadeIn space-y-4 opacity-0" style={{ animationDuration: "0.7s" }}>
+          <Card className="border border-red-200 bg-red-50 dark:bg-red-900/20">
+            <div className="p-4 text-center space-y-2">
+              <ExclamationTriangleIcon className="h-8 w-8 text-red-500 mx-auto" />
+              <h3 className="text-lg font-semibold text-red-800 dark:text-red-400">
+                {m.mount_error_title()}
+              </h3>
+              <p className="text-sm text-red-600 dark:text-red-400">
+                {downloadError}
+              </p>
+            </div>
+          </Card>
+          <div className="flex w-full justify-end space-x-2">
+            <Button size="MD" theme="light" text={m.back()} onClick={onBack} />
+            <Button
+              size="MD"
+              theme="primary"
+              text={m.mount_button_back_to_overview()}
+              onClick={() => setDownloadViewState("idle")}
+            />
+          </div>
+        </div>
+      )}
+    </div>
+  );
+}
+
 function ErrorView({
   errorMessage,
   onClose,

usb_mass_storage.go

@@ -1,6 +1,7 @@
 package kvm
 
 import (
+	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -87,7 +88,7 @@ func mountImage(imagePath string) error {
 
 var nbdDevice *NBDDevice
 
-const imagesFolder = "/userdata/jetkvm/images"
+var imagesFolder = "/userdata/jetkvm/images"
 
 func initImagesFolder() error {
 	err := os.MkdirAll(imagesFolder, 0755)
@@ -612,3 +613,232 @@ func handleUploadHttp(c *gin.Context) {
 
 	c.JSON(http.StatusOK, gin.H{"message": "Upload completed"})
 }
+
+// Download state management
+type DownloadState struct {
+	Downloading bool    `json:"downloading"`
+	Filename    string  `json:"filename,omitempty"`
+	URL         string  `json:"url,omitempty"`
+	TotalBytes  int64   `json:"totalBytes"`
+	DoneBytes   int64   `json:"doneBytes"`
+	Progress    float32 `json:"progress"`
+	Error       string  `json:"error,omitempty"`
+}
+
+var currentDownload *DownloadState
+var downloadMutex sync.Mutex
+var downloadCancel context.CancelFunc
+
+func rpcGetDownloadState() (*DownloadState, error) {
+	downloadMutex.Lock()
+	defer downloadMutex.Unlock()
+	if currentDownload == nil {
+		return &DownloadState{Downloading: false}, nil
+	}
+	return currentDownload, nil
+}
+
+func rpcCancelDownload() error {
+	downloadMutex.Lock()
+	defer downloadMutex.Unlock()
+	if downloadCancel != nil {
+		downloadCancel()
+		downloadCancel = nil
+	}
+	return nil
+}
+
+func rpcDownloadFromUrl(url string, filename string) error {
+	// Sanitize filename
+	sanitizedFilename, err := sanitizeFilename(filename)
+	if err != nil {
+		return err
+	}
+
+	// Validate URL
+	if !strings.HasPrefix(url, "http://") && !strings.HasPrefix(url, "https://") {
+		return errors.New("invalid URL: must start with http:// or https://")
+	}
+
+	// Check if already downloading
+	downloadMutex.Lock()
+	if currentDownload != nil && currentDownload.Downloading {
+		downloadMutex.Unlock()
+		return errors.New("another download is already in progress")
+	}
+
+	// Check if file already exists
+	filePath := filepath.Join(imagesFolder, sanitizedFilename)
+	if _, err := os.Stat(filePath); err == nil {
+		downloadMutex.Unlock()
+		return fmt.Errorf("file already exists: %s", sanitizedFilename)
+	}
+
+	// Initialize download state
+	ctx, cancel := context.WithCancel(context.Background())
+	downloadCancel = cancel
+	currentDownload = &DownloadState{
+		Downloading: true,
+		Filename:    sanitizedFilename,
+		URL:         url,
+		Progress:    0,
+	}
+	downloadMutex.Unlock()
+
+	// Start download in goroutine
+	go performDownload(ctx, url, sanitizedFilename)
+
+	return nil
+}
+
+func performDownload(ctx context.Context, url string, filename string) {
+	downloadPath := filepath.Join(imagesFolder, filename+".incomplete")
+	finalPath := filepath.Join(imagesFolder, filename)
+
+	defer func() {
+		downloadMutex.Lock()
+		if currentDownload != nil {
+			currentDownload.Downloading = false
+		}
+		downloadCancel = nil
+		downloadMutex.Unlock()
+		broadcastDownloadState()
+	}()
+
+	// Create HTTP request with context
+	req, err := http.NewRequestWithContext(ctx, "GET", url, nil)
+	if err != nil {
+		setDownloadError(fmt.Sprintf("failed to create request: %v", err))
+		return
+	}
+
+	// Perform request
+	client := &http.Client{Timeout: 0} // No timeout for large downloads
+	resp, err := client.Do(req)
+	if err != nil {
+		if ctx.Err() == context.Canceled {
+			setDownloadError("download cancelled")
+			// Clean up incomplete file
+			os.Remove(downloadPath)
+		} else {
+			setDownloadError(fmt.Sprintf("failed to download: %v", err))
+		}
+		return
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		setDownloadError(fmt.Sprintf("server returned status %d", resp.StatusCode))
+		return
+	}
+
+	totalSize := resp.ContentLength
+	if totalSize <= 0 {
+		setDownloadError("server did not provide content length")
+		return
+	}
+
+	// Update state with total size
+	downloadMutex.Lock()
+	if currentDownload != nil {
+		currentDownload.TotalBytes = totalSize
+	}
+	downloadMutex.Unlock()
+	broadcastDownloadState()
+
+	// Create file
+	file, err := os.Create(downloadPath)
+	if err != nil {
+		setDownloadError(fmt.Sprintf("failed to create file: %v", err))
+		return
+	}
+	defer file.Close()
+
+	// Download with progress tracking
+	var written int64
+	buf := make([]byte, 32*1024)
+	lastProgress := float32(0)
+
+	for {
+		select {
+		case <-ctx.Done():
+			setDownloadError("download cancelled")
+			file.Close()
+			os.Remove(downloadPath)
+			return
+		default:
+		}
+
+		nr, er := resp.Body.Read(buf)
+		if nr > 0 {
+			nw, ew := file.Write(buf[0:nr])
+			if nw < nr {
+				setDownloadError(fmt.Sprintf("short write: %d < %d", nw, nr))
+				return
+			}
+			written += int64(nw)
+			if ew != nil {
+				setDownloadError(fmt.Sprintf("write error: %v", ew))
+				return
+			}
+
+			progress := float32(written) / float32(totalSize)
+			if progress-lastProgress >= 0.01 {
+				downloadMutex.Lock()
+				if currentDownload != nil {
+					currentDownload.DoneBytes = written
+					currentDownload.Progress = progress
+				}
+				downloadMutex.Unlock()
+				broadcastDownloadState()
+				lastProgress = progress
+			}
+		}
+		if er != nil {
+			if er == io.EOF {
+				break
+			}
+			setDownloadError(fmt.Sprintf("read error: %v", er))
+			return
+		}
+	}
+
+	// Sync filesystem
+	file.Sync()
+	file.Close()
+
+	// Rename to final filename
+	if err := os.Rename(downloadPath, finalPath); err != nil {
+		setDownloadError(fmt.Sprintf("failed to rename file: %v", err))
+		return
+	}
+
+	// Update final state
+	downloadMutex.Lock()
+	if currentDownload != nil {
+		currentDownload.DoneBytes = totalSize
+		currentDownload.Progress = 1.0
+	}
+	downloadMutex.Unlock()
+
+	logger.Info().Str("filename", filename).Int64("size", totalSize).Msg("download completed")
+}
+
+func setDownloadError(errMsg string) {
+	downloadMutex.Lock()
+	if currentDownload != nil {
+		currentDownload.Error = errMsg
+	}
+	downloadMutex.Unlock()
+	logger.Warn().Str("error", errMsg).Msg("download error")
+}
+
+func broadcastDownloadState() {
+	downloadMutex.Lock()
+	state := currentDownload
+	downloadMutex.Unlock()
+
+	if currentSession != nil && state != nil {
+		writeJSONRPCEvent("downloadState", state, currentSession)
+	}
+}

usb_mass_storage_test.go

@@ -0,0 +1,95 @@
+package kvm
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestSanitizeFilename(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		expected string
+		wantErr  bool
+	}{
+		{"Simple filename", "image.iso", "image.iso", false},
+		{"Filename with spaces", "my image.iso", "my image.iso", false},
+		{"Path traversal", "../image.iso", "", true},
+		{"Absolute path", "/etc/passwd", "", true},
+		{"Current directory", ".", "", true},
+		{"Parent directory", "..", "", true},
+		{"Root directory", "/", "", true},
+		{"Nested path", "folder/image.iso", "image.iso", false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := sanitizeFilename(tt.input)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("sanitizeFilename() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if got != tt.expected {
+				t.Errorf("sanitizeFilename() = %v, want %v", got, tt.expected)
+			}
+		})
+	}
+}
+
+func TestRpcDownloadFromUrl(t *testing.T) {
+	// Create temp directory for images
+	tmpDir := t.TempDir()
+	originalImagesFolder := imagesFolder
+	imagesFolder = tmpDir
+	defer func() { imagesFolder = originalImagesFolder }()
+
+	// Start test server
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Length", "12")
+		w.Write([]byte("test content"))
+	}))
+	defer ts.Close()
+
+	// Test download
+	filename := "test.iso"
+	err := rpcDownloadFromUrl(ts.URL, filename)
+	if err != nil {
+		t.Fatalf("rpcDownloadFromUrl() error = %v", err)
+	}
+
+	// Wait for download to complete (since it's async)
+	// In a real test we might need a better way to wait, but for now we can poll the state
+	timeout := time.After(2 * time.Second)
+	ticker := time.NewTicker(100 * time.Millisecond)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-timeout:
+			t.Fatal("timeout waiting for download")
+		case <-ticker.C:
+			state, _ := rpcGetDownloadState()
+			if state.Error != "" {
+				t.Fatalf("download failed with error: %s", state.Error)
+			}
+			if !state.Downloading && state.DoneBytes == 12 {
+				goto Done
+			}
+		}
+	}
+Done:
+
+	// Verify file content
+	content, err := os.ReadFile(filepath.Join(tmpDir, filename))
+	if err != nil {
+		t.Fatalf("failed to read downloaded file: %v", err)
+	}
+	if string(content) != "test content" {
+		t.Errorf("file content = %q, want %q", string(content), "test content")
+	}
+}