g1 rule update

[bblay]

No description provided.

[bblay]

Closing for now, until tests are added.

[bblay]

Re-opened for discussion (or just to merge?!).

I don't think we can use mocking for this.
The rules are all lumped together so we'd have to mock almost an entire grib message,
in order for it to pass through all the load rules.

If the rules were atomic python functions, like in grib_save,
we could just test one specific rule, as I've tried to do in #229.

I'm happy to be proved wrong.
Can anyone suggest how we might test just this one rule?

[rhattersley]

I can't see a sane way to only run one rule. But I don't think you really want to do that anyway. Testing a single if statement isn't much use to anyone. You want to test the related statements at the same time to make sure they aren't treading on each other's toes. (In other words, if the rules were expressed as functions then you wouldn't have a function for each rule, you'd have a function for each logical group of rules.)

That said, it doesn't look like it'd be that hard to run all the rules with a minimal mock grib message and check for a simple Cube with the relevant long_name. Most of the rules are "opt-in" rules, where a dumb mock object wouldn't pass the tests.

For example:

IF
grib.gridType=="regular_ll"
grib.jPointsAreConsecutive == 0
THEN
...

This wouldn't trigger as grib.gridType would return another Mock object, which wouldn't compare equal to "regular_ll".

For the very few "opt-out" rules, I'd probably just add attribute to the mock grib message which prevent them from triggering.

[bblay]

Thanks, excellent guidance @rhattersley, this works very nicely.

[bblay]

rebased

[bblay]

Anyone want to pick this up for Bernd?
https://groups.google.com/forum/#!topic/scitools-iris/qjvJyXp6JGc

[rhattersley]

@bblay - this PR currently needs a rebase - so it'd be best to get that done before going over the code again.

[bblay]

Rebased. Tests no longer working.

======================================================================
ERROR: test_table1_localparam (__main__.TestGribLoadRules)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "test_grib_load.py", line 57, in test_table1_localparam
    iris.fileformats.grib._load_rules.verify(cube, grib)
  File "/home/h05/itbb/.local/lib/python2.7/site-packages/iris/fileformats/rules.py", line 602, in verify
    rule_factories = rule.run_actions(cube, field)
  File "/home/h05/itbb/.local/lib/python2.7/site-packages/iris/fileformats/rules.py", line 391, in run_actions
    raise err
TypeError: %d format: a number is required, not Mock