chore: use before_request hook for dynamic routes

[benjreinhart]

SUMMARY

This PR leverages a new FAB feature to allow certain features to be enabled/disabled at runtime rather than once during boot. Routes will 404 if features are disabled, which is the same functionality present today. It also presents a consistent way to handle conditional route availability, giving us an opportunity to unify how this type of thing is handled.

Notes

This PR also introduces a new pattern for enabling/disabling feature flags per test using the with_feature_flags decorator. Example:

class TestYourFeature(SupersetTestCase):

    @with_feature_flags(YOUR_FEATURE=True)
    def test_your_feature_enabled(self):
        self.assertEqual(is_feature_enabled("YOUR_FEATURE"), True)

    @with_feature_flags(YOUR_FEATURE=False, ANOTHER_FEATURE=True)
    def test_your_feature_disabled(self):
        self.assertEqual(is_feature_enabled("YOUR_FEATURE"), False)
        self.assertEqual(is_feature_enabled("ANOTHER_FEATURE"), True)

TEST PLAN

Manual/unit/fab tests.

cc @dpgaspar @robdiciuccio @craig-rueda

[craig-rueda]

LGTM

[codecov]

Codecov Report

Merging #14568 (4a5b33e) into master (e4d2424) will decrease coverage by 0.17%.
The diff coverage is 97.29%.

❗ Current head 4a5b33e differs from pull request most recent head 5700897. Consider uploading reports for the commit 5700897 to get more accurate results

@@            Coverage Diff             @@
##           master   #14568      +/-   ##
==========================================
- Coverage   77.47%   77.30%   -0.18%     
==========================================
  Files         958      959       +1     
  Lines       48486    48512      +26     
  Branches     5679     5681       +2     
==========================================
- Hits        37565    37500      -65     
- Misses      10721    10812      +91     
  Partials      200      200              

Flag	Coverage Δ
hive	?
mysql	81.39% <97.29%> (+0.15%)	⬆️
postgres	81.41% <97.29%> (+0.15%)	⬆️
presto	?
python	81.46% <97.29%> (-0.33%)	⬇️
sqlite	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
superset/reports/logs/api.py	94.11% <87.50%> (-1.34%)	⬇️
superset/app.py	81.31% <100.00%> (-0.07%)	⬇️
superset/charts/api.py	86.22% <100.00%> (+4.29%)	⬆️
superset/dashboards/api.py	92.30% <100.00%> (+4.63%)	⬆️
superset/reports/api.py	87.78% <100.00%> (+0.68%)	⬆️
superset/utils/urls.py	100.00% <100.00%> (ø)
superset/db_engines/hive.py	0.00% <0.00%> (-82.15%)	⬇️
...et-frontend/src/components/Menu/LanguagePicker.tsx	64.28% <0.00%> (-20.72%)	⬇️
superset/db_engine_specs/hive.py	70.32% <0.00%> (-17.08%)	⬇️
superset/db_engine_specs/presto.py	83.36% <0.00%> (-6.95%)	⬇️
... and 15 more

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[robdiciuccio]

Is there any test coverage for the affected endpoints?

[benjreinhart]

@robdiciuccio yes and no. The feature flags are True in the test environment, and so the happy path is tested. However, there are no automated tests that flip the switch on/off and observe the behavior. I felt confident in the change and did not attempt to add those, but can do so to boost confidence.

[robdiciuccio]

@benjreinhart Would be nice to have some tests to ensure the 404 response is working as intended. I realize it's a bit out of scope since these didn't exist in the first place, but hey, more test coverage!

[robdiciuccio]

LGTM, nice test enhancements!