GetHoverResponse should handle null response from server.

[kadircet]

As mentioned in Hover Request

Response:

result: Hover | null

Current implementation was failing with None object has no getitem method, with this patch it will provide more useful information.

---

This change is 

[bstaletic]

Can you make a test for the case where the response to the hover request is null? You can take a look at ycmd/tests/language_server/ to get an idea how those are written.
However, all hover tests are currently written against the java server, which never returns null, hence why we currently don't handle null response. Anyway, ask for help if you are stuck.

Reviewed 1 of 1 files at r1.
Reviewable status: 0 of 2 LGTMs obtained

[codecov]

Codecov Report

Merging #1110 into master will decrease coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1110      +/-   ##
==========================================
- Coverage   97.59%   97.58%   -0.02%     
==========================================
  Files          89       89              
  Lines        6988     6992       +4     
==========================================
+ Hits         6820     6823       +3     
- Misses        168      169       +1

[kadircet]

Added tests for GetHoverResponse, both for null and non-null case.

[micbou]

except a minor comment.

Reviewed 1 of 1 files at r1, 1 of 1 files at r2.
Reviewable status: 0 of 2 LGTMs obtained (and 1 stale)

---

ycmd/completers/language_server/language_server_completer.py, line 1311 at r2 (raw file):

      return result[ 'contents' ]
    raise RuntimeError( 'No hover information.' )

Unnecessary blank line.

[bstaletic]

I also left a minor comment. Squashing the commits into one would also be appreciated.
Apart from that,

Reviewed 1 of 1 files at r2.
Reviewable status: 1 of 2 LGTMs obtained (and 1 stale)

---

ycmd/tests/language_server/language_server_completer_test.py, line 621 at r2 (raw file):

                       side_effect = [ { 'result': { 'contents': 'test' } } ] ):
      assert_that(
        completer.GetHoverResponse( request_data ), equal_to( 'test' )

Nose provides eq_ so this whole assert can be fit on one line.

from nose.tools import eq_
eq_(actual, expected)

Also the raises( RuntimeError ) can take an optional parameter to match the exception string. For example raises( RuntimeError, 'No hover information' ). It might also be good to extract that string to a variable like it is done in ycmd/tests/bindings/cpp_bindings_raises_exception_test.py.

[kadircet]

Addressed all the comments and squashed commits.

[bstaletic]

Thanks for the PR.
@zzbot r+

[zzbot]

📌 Commit e1a6e18 has been approved by bstaletic

[zzbot]

⌛ Testing commit e1a6e18 with merge 50a358b...

[zzbot]

💔 Test failed - status-travis

[micbou]

@zzbot retry

[zzbot]

⌛ Testing commit e1a6e18 with merge ad978f4...

[zzbot]

☀️ Test successful - status-appveyor, status-travis
Approved by: bstaletic
Pushing ad978f4 to master...