Fix enum constant printing and add FileCheck to all Enum tests

[gmagogsfm]

Stack from ghstack:

• Enable Enum pickling/unpickling. #43188 Enable Enum pickling/unpickling.
• Add Enum TorchScript serialization and deserialization support #42963 Add Enum TorchScript serialization and deserialization support
• Fix enum constant printing and add FileCheck to all Enum tests #42874 Fix enum constant printing and add FileCheck to all Enum tests
• Add Enum convert back to Python object support #43121 Add Enum convert back to Python object support

Differential Revision: D23222894

[dr-ci]

💊 CI failures summary and remediations

As of commit 555e352 (more details on the Dr. CI page):

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• 1/1 failures possibly* introduced in this PR
  • 1/1 non-CircleCI failure(s)

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ci.pytorch.org: 1 failed

• Failed: pr/pytorch-linux-xenial-rocm3.5.1-py3.6

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This comment has been revised 8 times.

[SplitInfinity]

What is the motivation for this PR?

I worry that the IR representation of Enums is an internal implementation detail that shouldn't matter much as long as enums behave as they should (which we already have tests for).

[gmagogsfm]

What is the motivation for this PR?

I worry that the IR representation of Enums is an internal implementation detail that shouldn't matter much as long as enums behave as they should (which we already have tests for).

It is technically internal implementation detail from end-user's perspective. But I think it is still worth testing that key parts of IR is generated correctly. These filechecks are cheap and key parts (type annotation, how constants are printed etc) shouldn't change that much.

[facebook-github-bot]

@gmagogsfm merged this pull request in 8eb3de7.