Bazelize bazel-bench

[joeleba]

What this PR does and why we need it:

This PR enables the use of Bazel to build & test bazel-bench.

New changes / Issues that this PR fixes:

• Added various build/test targets.
• Updated README to reflect this big change.

Special notes for reviewer:

If possible, try to clone and set up the project from scratch.

Does this require a change in the script's interface or the BigQuery's table structure?

No

[meisterT]

I get:
DEBUG: Rule 'io_bazel_rules_python' indicated that a canonical reproducible form can be obtained by modifying arguments shallow_since = "1551999322 -0500"

and three failing tests (the build succeeds). Is that expected?

[Globegitter]

Not sure if these BUILD files where generated by hand, but I had success using https://github.com/tuomasr/pazel to generate optimal BUILD files for me (sometimes with a little bit of hand tweaking afterwards). Also there are alternative rules to interact with pip: https://github.com/apt-itude/rules_pip. They support sub-dependency locking out of the box, could be worth giving a shot. Anyway, just my two cents, feel free to ignore.

[joeleba]

I've made some changes. You shouldn't need pip and virtualenv now. Just bazel.

[joeleba]

Not sure if these BUILD files where generated by hand, but I had success using https://github.com/tuomasr/pazel to generate optimal BUILD files for me (sometimes with a little bit of hand tweaking afterwards). Also there are alternative rules to interact with pip: https://github.com/apt-itude/rules_pip. They support sub-dependency locking out of the box, could be worth giving a shot. Anyway, just my two cents, feel free to ignore.

@Globegitter thanks for the recommendation! Yes, those were generated by hand.

[meisterT]

What's the motivation to move this import down here?

[joeleba]

It's a workaround of bazelbuild/rules_python#14 for bazel test to work.