Throw error on incorrect download sizes

src/helpers.js

@@ -182,32 +182,43 @@ module.exports.downloadFile = (url, destination, progressCallback, completeCallb
     .get(url, {
       responseType: 'stream',
     })
-    .then((response) => {
-      const stream = fs.createWriteStream(destination);
+    .then(response => {
       const total = parseInt(response.headers['content-length'], 10);
-      let downloaded = 0;
-      response.data.on('data', (chunk) => {
-        stream.write(Buffer.from(chunk));
-        downloaded += chunk.length;
-        if (progressCallback) {
-          progressCallback((downloaded / total * 100.0).toFixed(2));
-        }
-      });
+      if (total === 0) {
+        throw Error('No data available for download');
+      } else {
+        const stream = fs.createWriteStream(destination);
 
-      response.data.on('end', () => {
-        stream.end(() => {
-          completeCallback();
+        let downloaded = 0;
+        response.data.on('data', (chunk) => {
+          stream.write(Buffer.from(chunk));
+          downloaded += chunk.length;
+          if (progressCallback) {
+            progressCallback((downloaded / total * 100.0).toFixed(2));
+          }
         });
-      });
 
-      response.data.on('error', (e) => {
-        stream.end(() => {
-          completeCallback(e);
+        response.data.on('end', () => {
+          stream.end(() => {
+            if (downloaded === 0) {
+              throw Error('Received 0 bytes');
+            } else if (downloaded !== total) {
+              throw Error('Received incorrect number of bytes');
+            } else {
+              completeCallback();
+            }
+          });
         });
-      });
+
+        response.data.on('error', error => {
+          stream.end(() => {
+            completeCallback(error);
+          });
+        });
+      }
     })
-    .catch((e)=> {
-      completeCallback(e);
+    .catch(error => {
+      completeCallback(error);
     });
 };