Fix FakeProviderForBackendV2.get_backend bug

[HuangJunye]

Summary

Previously, FakeProviderForBackendV2.get_backend("fake_backend_name") raises an error due to API change in BackendV2. This PR fixes this bug.

Fix #8531

Details and comments

• Fixed get_backend issue
• Updated fake provider module API code example to use provider.get_backend syntax
• Added test_fake_provider.py

[qiskit-bot]

Thank you for opening a new pull request.

Before your PR can be merged it will first need to pass continuous integration tests and be reviewed. Sometimes the review process can be slow, so please be patient.

While you're waiting, please feel free to review other open PRs. While only a subset of people are authorized to approve pull requests for merging, everyone is encouraged to review open pull requests. Doing reviews helps reduce the burden on the core team and helps make the project's code better for everyone.

One or more of the the following people are requested to review this:

• @Qiskit/terra-core

[coveralls]

Pull Request Test Coverage Report for Build 2902618988

• 0 of 1 (0.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.003%) to 84.054%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
qiskit/providers/fake_provider/fake_provider.py	0	1	0.0%

Totals
Change from base Build 2890590743:	0.003%
Covered Lines:	56324
Relevant Lines:	67009

---

💛 - Coveralls

[acastanedam]

Hi @HuangJunye, I am also interested in this fix. I think the test is not passing because in the assertion (line 37) the target for insinstance should be FakeManilaV2. Probably, to be more general such assertion could be written in terms of the version: assert backend.version == 2.

[acastanedam]

Hi, in regard to this PR, is it still feasible to include it or should one move towards the use of BackendV2Converter ?.
Thansk in advance.

[HuangJunye]

Hi, in regard to this PR, is it still feasible to include it or should one move towards the use of BackendV2Converter ?.

Thansk in advance.

Sorry for keeping the this PR staled for so long. I think we can include it. I just need to add tests. I'll get to it next week

[acastanedam]

Hi, could I cooperate to include this PR?

[ajavadia]

@HuangJunye can you please update this branch so this bug can be fixed?

[acastanedam]

Hi, one question, will be this PR included in the current dev branch?. The problem is still there, I can volunteer to help in there as I really need the fix.
Thanks in advance

[HuangJunye]

@acastanedam I accidentally deleted the branch. I have been wanted to finish this for a year but I get distracted with other things. I apologize for the delay. Can ask for your help to finish this? You can open a new PR and copy over the changes I have made so far and add tests. That should be enough to finish it.