Fixing exists() method on s3 provider.

Fails due to error thrown by client.

Author: jthomas

src/index.ts

@@ -32,3 +32,4 @@ export function getStorageProvider(providerId: string): StorageProvider {
 }
 
 export * from './providers/interface'
+export { StorageClient } from './providers/interface'

src/providers/s3.ts

@@ -27,7 +27,7 @@ import { WritableStream } from 'memory-streams'
 import makeDebug from 'debug'
 const debug = makeDebug('nim:storage-s3')
 
-class S3RemoteFile implements RemoteFile {
+export class S3RemoteFile implements RemoteFile {
   private s3: S3Client
   private bucketName: string
   private web: boolean
@@ -79,7 +79,15 @@ class S3RemoteFile implements RemoteFile {
 
   async exists(): Promise<boolean> {
     debug('exists was called for file %s', this.name)
-    return !!await this.getMetadata()
+    try {
+      await this.getMetadata()
+    } catch (err) {
+      if (err?.$metadata?.httpStatusCode === 404) {
+        return false
+      }
+      throw err
+    }
+    return true
   }
 
   delete(): Promise<any> {

tests/s3.test.ts

@@ -1,5 +1,7 @@
 import provider, { NimS3Client } from '@nimbella/storage/providers/s3'
 import { StorageKey } from '@nimbella/storage/providers/interface'
+import {S3RemoteFile} from '../src/providers/s3'
+import {S3Client} from '@aws-sdk/client-s3'
 
 describe('test prepareCredentials method', () => {
   test('should return credentials instance from input parameters', () => {
@@ -25,3 +27,39 @@ describe('test getClient method', () => {
     expect(client.getBucketName()).toEqual(`data-${namespace}-api-nimbella-io`)
   })
 })
+
+describe('test file.exists() method', () => {
+  test('should return true if file exists', async () => {
+    const client = { send: async () => ({ storageClass: null, ContentLength: null, etag: null }) }
+    const file = new S3RemoteFile((client as unknown) as S3Client, '', '', false)
+    expect(await file.exists()).toBeTruthy()
+  })
+  test('should return false if file does not exist', async () => {
+    class ServiceError extends Error {
+      "$metadata": {}
+    }
+    const client = {
+      send: async () => {
+        const err = new ServiceError('Missing file')
+        err["$metadata"] = { httpStatusCode: 404 }
+        throw err
+      } 
+    }
+    const file = new S3RemoteFile((client as unknown) as S3Client, '', '', false)
+    expect(await file.exists()).toBeFalsy()
+  })
+  test('should throw error otherwise', async () => {
+    class ServiceError extends Error {
+      "$metadata": {}
+    }
+    const client = {
+      send: async () => {
+        const err = new ServiceError('Some error message')
+        err["$metadata"] = { httpStatusCode: 500 }
+        throw err
+      } 
+    }
+    const file = new S3RemoteFile((client as unknown) as S3Client, '', '', false)
+    return expect(file.exists()).rejects.toThrow('Some error message');
+  })
+})