fix(techdocs): make aws and gcs tests pass

Co-authored-by: Eric Peterson <ericpeterson@spotify.com>
Signed-off-by: Camila Belo <camilaibs@gmail.com>

packages/techdocs-common/__mocks__/@google-cloud/storage.ts

@@ -107,6 +107,17 @@ class Bucket {
   file(destinationFilePath: string) {
     return new GCSFile(destinationFilePath);
   }
+
+  getFilesStream() {
+    const readable = new Readable();
+    readable._read = () => {};
+
+    process.nextTick(() => {
+      readable.emit('end');
+    });
+
+    return readable;
+  }
 }
 
 export class Storage {

packages/techdocs-common/__mocks__/aws-sdk.ts

@@ -104,6 +104,14 @@ export class S3 {
         }),
     };
   }
+
+  listObjectsV2() {
+    return {
+      promise: () => {
+        return Promise.resolve([]);
+      },
+    };
+  }
 }
 
 export default {

packages/techdocs-common/src/stages/publish/googleStorage.ts

@@ -15,7 +15,7 @@
  */
 import { Entity, EntityName } from '@backstage/catalog-model';
 import { Config } from '@backstage/config';
-import { FileExistsResponse, Storage } from '@google-cloud/storage';
+import { File, FileExistsResponse, Storage } from '@google-cloud/storage';
 import express from 'express';
 import JSON5 from 'json5';
 import path from 'path';
@@ -119,9 +119,7 @@ export class GoogleGCSPublish implements PublisherBase {
 
     // First, retrieve a list of all individual files in currently existing
     const remoteFolder = getCloudPathForLocalPath(entity);
-    const existingFiles = (
-      await bucket.getFiles({ prefix: remoteFolder })
-    )[0].map(file => file.name);
+    const existingFiles = await this.getFilesForFolder(remoteFolder);
 
     // Then, merge new files into the same folder
     let absoluteFilesToUpload;
@@ -276,4 +274,29 @@ export class GoogleGCSPublish implements PublisherBase {
       });
     });
   }
+
+  private getFilesForFolder(folder: string): Promise<string[]> {
+    const fileMetadataStream: Readable = this.storageClient
+      .bucket(this.bucketName)
+      .getFilesStream({ prefix: folder });
+
+    return new Promise((resolve, reject) => {
+      const files: string[] = [];
+
+      fileMetadataStream.on('error', error => {
+        // push file to file array
+        reject(error);
+      });
+
+      fileMetadataStream.on('data', (file: File) => {
+        // push file to file array
+        files.push(file.name);
+      });
+
+      fileMetadataStream.on('end', () => {
+        // resolve promise
+        resolve(files);
+      });
+    });
+  }
 }