add a single pixel image definition

and run it through the tests, engaging the sharp library to make sure it works

src/getOrCreateObject/getOrCreateObject.test.js

@@ -3,11 +3,17 @@ import { describe, it, expect } from 'vitest';
 import { mockClient } from 'aws-sdk-client-mock';
 import { GetObjectCommand, S3Client } from '@aws-sdk/client-s3';
 import { DynamoDBDocumentClient, GetCommand } from '@aws-sdk/lib-dynamodb';
+import { Readable } from 'stream';
 
 // Import the function to test.
 import { getOrCreateObject } from './getOrCreateObject.js';
 
 process.env.DYNAMODB_TABLE = 'test-table';
+process.env.ORIGINAL_BUCKET = 'test-bucket';
+
+// Create a 1 pixel jpg image as a readable stream,
+// so that the sharp library has something to resize.
+const singlePixelJpgReadable = Readable.from(Buffer.from('/9j/4AAQSkZJRgABAQEAAAAAAAD/2wBDAAoHBwkHBgoJCAkLCwoMDxkQDw4ODx4WFxIZJCAmJSMgIyIoLTkwKCo2KyIjMkQyNjs9QEBAJjBGS0U+Sjk/QD3/2wBDAQsLCw8NDx0QEB09KSMpPT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT3/wAARCAAIAAgDASIAAhEBAxEB/8QAHwAAAQUBAQEBAQEAAAAAAAAAAAECAwQFBgcICQoL/8QAtRAAAgEDAwIEAwUFBAQAAAF9AQIDAAQRBRIhMUEGE1FhByJxFDKBkaEII0KxwRVS0fAkM2JyggkKFhcYGRolJicoKSo0NTY3ODk6Q0RFRkdISUpTVFVWV1hZWmNkZWZnaGlqc3R1dnd4eXqDhIWGh4iJipKTlJWWl5iZmqKjpKWmp6ipqrKztLW2t7i5usLDxMXGx8jJytLT1NXW19jZ2uHi4+Tl5ufo6erx8vP09fb3+Pn6/8QAHwEAAwEBAQEBAQEBAQAAAAAAAAECAwQFBgcICQoL/8QAtREAAgECBAQDBAcFBAQAAQJ3AAECAxEEBSExBhJBUQdhcRMiMoEIFEKRobHBCSMzUvAVYnLRChYkNOEl8RcYGRomJygpKjU2Nzg5OkNERUZHSElKU1RVVldYWVpjZGVmZ2hpanN0dXZ3eHl6goOEhYaHiImKkpOUlZaXmJmaoqOkpaanqKmqsrO0tba3uLm6wsPExcbHyMnK0tPU1dbX2Nna4uPk5ebn6Onq8vP09fb3+Pn6/9oADAMBAAIRAxEAPwD9/KKKKAP/2Q==', 'base64'));
 
 // Mock the ddb client.
 const ddbMock = mockClient(DynamoDBDocumentClient);
@@ -19,26 +25,42 @@ ddbMock.on(GetCommand).resolves({
 
 // Mock the s3 client.
 const s3Mock = mockClient(S3Client);
-s3Mock.on(GetObjectCommand).resolves({
-  Body: 'test',
+
+// Reject all GetObjectCommand calls by default.
+s3Mock.on(GetObjectCommand).rejects({ Code: 'NoSuchKey' });
+
+// Define an existing object in the bucket, that returns a valid and rescalable image.
+s3Mock.on(GetObjectCommand, {
+  Bucket: 'test-bucket',
+  Key: 'original_media/www.bu.edu/somesite/files/01/exists.jpg',
+}).resolves({
+  Body: singlePixelJpgReadable,
+});
+
+// Define a second object in the bucket with a unicode filename.
+s3Mock.on(GetObjectCommand, {
+  Bucket: 'test-bucket',
+  Key: 'original_media/www.bu.edu/site/files/01/file-with-ñ.jpg',
+}).resolves({
+  Body: singlePixelJpgReadable,
 });
 
 describe('getOrCreateObject', () => {
-  it('should return an object', async () => {
+  it('should return an object if it exists', async () => {
     const result = await getOrCreateObject(
       {
-        url: 'https://example-1111.s3-object-lambda.us-east-1.amazonaws.com/somesite/files/01/example-150x150.jpg',
+        url: 'https://example-1111.s3-object-lambda.us-east-1.amazonaws.com/somesite/files/01/exists.jpg',
         headers: { },
       },
       'www.bu.edu',
     );
     expect(result.Body).toBeDefined();
   });
 
-  it('should return an an object, and parse the crop value', async () => {
+  it('should find the unscaled original for the request, scale it with the parsed crop value, and return an an object', async () => {
     const result = await getOrCreateObject(
       {
-        url: 'https://example-1111.s3-object-lambda.us-east-1.amazonaws.com/files/01/example-758x460.jpg?resize-position=left',
+        url: 'https://example-1111.s3-object-lambda.us-east-1.amazonaws.com/somesite/files/01/exists-758x460.jpg?resize-position=left',
         headers: { },
       },
       'www.bu.edu',