first cut at a (somewhat) useful hypothesis test

[kurtbrose]

No description provided.

[kurtbrose]

running locally gives interesting output:

> python -m pytest glom\test\test_auto.py --hypothesis-show-statistics
============================= test session starts =============================
platform win32 -- Python 2.7.12, pytest-3.5.1, py-1.5.2, pluggy-0.6.0
hypothesis profile 'default' -> database=DirectoryBasedExampleDatabase('C:\\Users\\Kurt\\workspace\\glom\\.hypothesis\\examples')
rootdir: C:\Users\Kurt\workspace\glom, inifile: pytest.ini
plugins: hypothesis-3.82.1
collected 1 item

glom\test\test_auto.py .                                                 [100%]
============================ Hypothesis Statistics ============================

glom/test/test_auto.py::TestSpecAndTarget::runTest:

  - 20 passing examples, 0 failing examples, 0 invalid examples
  - Typical runtimes: 0-4404 ms
  - Fraction of time spent in data generation: ~ 0%
  - Stopped because settings.max_examples=20

========================== 1 passed in 8.63 seconds ===========================

so..... does that mean a glom with 50 elements resulted in a 4 second runtime? owch I wonder which one that is

[codecov-io]

Codecov Report

Merging #66 into master will increase coverage by 0.09%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #66      +/-   ##
==========================================
+ Coverage   94.45%   94.55%   +0.09%     
==========================================
  Files          14       15       +1     
  Lines        1479     1505      +26     
  Branches      231      231              
==========================================
+ Hits         1397     1423      +26     
  Misses         47       47              
  Partials       35       35

Impacted Files	Coverage Δ
glom/test/test_auto.py	100% <100%> (ø)

---

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[codecov-io]

Codecov Report

Merging #66 into master will increase coverage by 0.09%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #66      +/-   ##
==========================================
+ Coverage   94.45%   94.55%   +0.09%     
==========================================
  Files          14       15       +1     
  Lines        1479     1505      +26     
  Branches      231      231              
==========================================
+ Hits         1397     1423      +26     
  Misses         47       47              
  Partials       35       35

Impacted Files	Coverage Δ
glom/test/test_auto.py	100% <100%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update ab822e3...296f35a. Read the comment docs.

[kurtbrose]

I'm not sure if this is actually useful yet vs our manual testing of every possible scenario

[kurtbrose]

got an idea -- one non-trivial invariant would be ensuring that scope propagates correctly

also: I'll keep building up this branch going off to the side -- the first time that it correctly identifies a new bug I'll merge to master