Fix S3 resource identifier order bug

[danielgtaylor]

This change is for the issue described in #59 and updates the model based on
the output of the proposed change in amazon-archives/aws-model-validators#2. The
following now works properly:

import boto3

obj = boto3.resource('s3').Bucket('foo').Object('bar')
mpu = obj.initiate_multipart_upload()
part = mpu.MultipartUploadPart(1)
print(part.object_key)
# => 'foo'

cc @jamesls @kyleknap

[coveralls]

Coverage remained the same at 98.58% when pulling 08df735c0a5fa6f8a851e96a622e696b4d5d20bc on s3-ident-fix into f04f5e3 on develop.

[kyleknap]

Would there be any way to add a test for this? Maybe an integration test? I would suggest just creating a multipart upload, uploading a part, and then listing the parts for the assertion. You do not need to do a full multipart upload as that requires more than 5 MB data transferred.

[danielgtaylor]

@kyleknap there is a test added here:

https://github.com/awslabs/aws-model-validators/pull/2/files#diff-e4bf191bb600a1c7130f57d133bf1e5e

Part of the advantage of adding it to the validator is that each SDK doesn't need to duplicate the effort. Do you think we should still add some extra test for this in Boto3?

[kyleknap]

I would say an integration for multipart upload in boto3 would be nice. Its a fairly used operation and it would not take too much time (when running the test) to instantiate a multipart upload, upload a single small (under < 5MB) part, and then complete the multipart upload. And that should succeed because there is only one part involved in the multipart upload.

[coveralls]

Coverage remained the same at 98.61% when pulling aaab03e on s3-ident-fix into 28ae6a8 on develop.

[jamesls]

This test doesn't assert anything. What about downloading the object and verifying its contents are b'hello, world!'?

[coveralls]

Coverage remained the same at 98.61% when pulling df4d95b on s3-ident-fix into 28ae6a8 on develop.

[kyleknap]

Thanks for adding the integration test. 🚢

[jamesls]