[Bug Fix/Feature] Enable logging within callback

[tchaton]

What does this PR do?

This PR enables logging within callback containing val and will be extended to all in future commit.

What changed:

• Add in run_evaluation function, model._result = Result() at the beginning to enable logging on all callbacks.
• Re-ordering latest hooks call within run_evaluation to happen before pushing to logger.
• Add a scriptable Callback to simplify tests

Fixes #3813

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[pep8speaks]

Hello @tchaton! Thanks for updating this PR.

• In the file pytorch_lightning/trainer/connectors/logger_connector.py:

Line 222:1: W293 blank line contains whitespace

• In the file pytorch_lightning/trainer/evaluation_loop.py:

Line 114:9: E265 block comment should start with '# '

• In the file pytorch_lightning/trainer/trainer.py:

Line 599:1: W293 blank line contains whitespace

• In the file tests/base/callback.py:

Line 5:1: E302 expected 2 blank lines, found 1
Line 7:121: E501 line too long (123 > 120 characters)
Line 7:124: W291 trailing whitespace
Line 26:1: W293 blank line contains whitespace
Line 29:1: W293 blank line contains whitespace
Line 30:32: W292 no newline at end of file

• In the file tests/models/test_onnx.py:

Line 135:1: E302 expected 2 blank lines, found 1

• In the file tests/trainer/logging/test_eval_loop_logging_1_0.py:

Line 325:1: E302 expected 2 blank lines, found 1
Line 337:121: E501 line too long (176 > 120 characters)
Line 339:1: W293 blank line contains whitespace
Line 378:121: E501 line too long (126 > 120 characters)
Line 378:126: E502 the backslash is redundant between brackets
Line 379:16: E128 continuation line under-indented for visual indent
Line 379:86: E502 the backslash is redundant between brackets
Line 380:80: E502 the backslash is redundant between brackets

Comment last updated at 2020-10-16 10:24:33 UTC

[codecov]

Codecov Report

Merging #4167 into master will increase coverage by 1%.
The diff coverage is 98%.

@@           Coverage Diff           @@
##           master   #4167    +/-   ##
=======================================
+ Coverage      92%     93%    +1%     
=======================================
  Files         103     103            
  Lines        7792    7840    +48     
=======================================
+ Hits         7147    7273   +126     
+ Misses        645     567    -78