Correct logic of Scenario.years_active()

[khaeru]

Closes #278.
Closes #279.

• Scenario.years_active() and .vintage_and_active_years() are improved.
• test_years_active() is rewritten to be more explicit.
• test_years_active() was incorrect. In this PR, the period '2050' is removed from the expected return value. See the inline comments:

  message_ix/tests/test_core.py

  Lines 222 to 228 in 3585ab3

  	# technical_lifetime of seattle/canning_plant/2020 is 30 years.
  	# - constructed in 2011-01-01.
  	# - by 2020-12-31, has operated 10 years.
  	# - operates until 2040-12-31.
  	# - is NOT active within the period '2050' (2041-01-01 to 2050-12-31)
  	result = scen.years_active('seattle', 'canning_plant', '2020')
  	npt.assert_array_equal(result, years[1:-1])

I have followed our documentation, specifically here where it reads:

In MESSAGEix, the key of an element in set year identifies the last year of the period, i.e., in a set year = [2000, 2005, 2010, 2015], the period ‘2010’ comprises the years [2006, .., 2010].

IMO this is more confusing than it needs to be, and we should rename 'year' to 'period' to disambiguate.

PR checklist:

• Tests added.
• Documentation added.
• Release notes updated.

[codecov]

Codecov Report

Merging #281 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master    #281      +/-   ##
=========================================
+ Coverage   78.19%   78.2%   +0.01%     
=========================================
  Files          13      13              
  Lines        1142    1138       -4     
=========================================
- Hits          893     890       -3     
+ Misses        249     248       -1

Impacted Files	Coverage Δ
message_ix/core.py	90.64% <100%> (+0.35%)	⬆️

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[OFR-IIASA]

@khaeru I have managed to switch branches and this looks fine to me. Should we also resolve issue #279 with this PR?

[OFR-IIASA]

Successfully tested.

[khaeru]

Should we also resolve issue #279 with this PR?

Yes, I already did. See the description at the top, and the commit message for 5f6deae.

[khaeru]

Note that the CI checks passed for cca6a25, then failed for 0022513. This seems to be the same symptom as noted here on #276.

[khaeru]

Note that the CI checks passed for cca6a25, then failed for 0022513. This seems to be the same symptom as noted here on #276.

66d5b4d brings in the fix for this issue from master. If the checks pass with this change, I will merge.

[khaeru]

Total coding time on this, #278, #279, and #283: 2 hours 20 minutes.
Discussion, filing #282, monitoring CI: about 1:00.