diff --git a/packages/image-upload/src/Files.test.ts b/packages/image-upload/src/Files.test.ts
new file mode 100644
index 0000000..2fc515d
--- /dev/null
+++ b/packages/image-upload/src/Files.test.ts
@@ -0,0 +1,54 @@
+import * as Files from './Files'
+
+describe('Files', () => {
+
+  const pngDataURL = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUg' +
+    'AAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNkYPhfDwAChwGA60e6kgAAAABJRU5ErkJggg=='
+
+  function base64ToArrayBuffer(base64: string): ArrayBuffer {
+    const bytesString = atob(base64)
+    const arrayBuffer = new ArrayBuffer(bytesString.length)
+    const iArray = new Uint8Array(arrayBuffer)
+    for (let i = 0; i < bytesString.length; i++) {
+      iArray[i] = bytesString.charCodeAt(i)
+    }
+    return arrayBuffer
+  }
+
+  function dataURLToBlob(dataURL: string) {
+    const [type, base64] = dataURL.split(';base64,', 2)
+    const arrayBuffer = base64ToArrayBuffer(base64)
+
+    return new Blob([arrayBuffer], {
+      type: type.replace(/^data:/, ''),
+    })
+  }
+
+  const pngBlob = dataURLToBlob(pngDataURL)
+
+  describe('readAsDataURL', () => {
+    it('asynchronously reads a file and returns a base64 string', async () => {
+      const file = new File([pngBlob], 'test.png', {
+        type: pngBlob.type,
+      })
+      const result = await Files.readAsDataURL(file)
+      expect(result).toEqual(pngDataURL)
+    })
+  })
+
+  describe('readAsArrayBuffer', () => {
+    it('asynchronously reads a file and returns an ArrayBuffer', async () => {
+      const base64 = pngDataURL.split(';base64,', 2)[1]
+      const file = new File([pngBlob], 'test.png', {
+        type: pngBlob.type,
+      })
+      const result = await Files.readAsArrayBuffer(file)
+      expect(result).toEqual(base64ToArrayBuffer(base64))
+    })
+  })
+
+  // describe('readAsArrayBuffer', () => {
+
+  // })
+
+})
diff --git a/packages/image-upload/src/Files.ts b/packages/image-upload/src/Files.ts
index 53565f9..dd88d97 100644
--- a/packages/image-upload/src/Files.ts
+++ b/packages/image-upload/src/Files.ts
@@ -4,7 +4,8 @@ function attachErrorListener(
   file: File,
   reject: (err: Error) => void,
 ) {
-  reader.onerror = ev => reject(new Error('Error reading file: ' + file.name))
+  reader.onerror = ev => reject(new Error('Error reading file: ' +
+    (reader.error ? reader.error.message : file.name)))
 }
 
 export async function readAsDataURL(file: File): Promise<string> {