unit tests: replace nose with pytest (#2502)

* Porting: substitute nose with ytest

This huge commit substitutes nose with pytest as a testing system. Things done here:

* deleted external/nose as it is no longer used
* moved mock resources in their own directory 'test/mock/'
* ported two tests (cmd/find, build_system) to pytest native syntax as an example
* build_environment, log: used monkeypatch instead of try/catch
* moved global mocking of fetch_cache to an auto-used fixture
* moved global mocking from test/__init__.py to conftest.py
* made `spack test` a wrapper around pytest
* run-unit-tests: avoid running python 2.6 tests under coverage to speed them up
* use `pytest --cov` instead of coverage run to cut down testing time

* mock/packages_test: moved mock yaml configuration to files instead of leaving it in the code as string literals

* concretize.py: ported tests to native pytest, reverted multiprocessing in pytest.ini as it was creating the wrong report for coveralls

* conftest.py, fixtures: added docstrings

* concretize_preferences.py: uses fixtures instead of subclassing MockPackagesTest

* directory_layout.py: uses fixtures instead of subclassing MockPackagesTest

* install.py: uses fixtures instead of subclassing MockPackagesTest

* optional_deps.py: uses fixtures instead of subclassing MockPackagesTest

optional_deps.py: uses fixtures instead of subclassing MockPackagesTest

* packages.py: uses fixtures instead of subclassing MockPackagesTest

* provider_index.py: uses fixtures instead of subclassing MockPackagesTest

* spec_yaml.py: uses fixtures instead of subclassing MockPackagesTest

* multimethod.py: uses fixtures instead of subclassing MockPackagesTest

* install.py: now uses mock_archive_url

* git_fetch.py: uses fixtures instead of subclassing MockPackagesTest

* hg_fetch.py: uses fixtures instead of subclassing MockPackagesTest

* svn_fetch.py, mirror.py: uses fixtures instead of subclassing MockPackagesTest
repo.py: deleted

* test_compiler_cmd.py: uses fixtures instead of subclassing MockPackagesTest

* cmd/module.py, cmd/uninstall.py: uses fixtures instead of subclassing MockDatabase

* database.py: uses fixtures instead of subclassing MockDatabase, removed mock/database

* pytest: uncluttering fixture implementations

* database: changing the scope to 'module'

* config.py: uses fixtures instead of subclassing MockPackagesTest

* spec_dag.py, spec_semantics.py: uses fixtures instead of subclassing MockPackagesTest

* stage.py: uses fixtures instead of subclassing MockPackagesTest. Removed mock directory

* pytest: added docstrings to all the fixtures

* pytest: final cleanup

* build_system_guess.py: fixed naming and docstrings as suggested by @scheibelp

* spec_syntax.py: added expected failure on parsing multiple specs closes #1976

* Add pytest and pytest-cov to Spack externals.

* Make `spack flake8` ignore externals.

* run-unit-tests runs spack test and not pytest.

* Remove all the special stuff for `spack test`

- Remove `conftest.py` magic and all the special case stuff in `bin/spack`

- Spack commands can optionally take unknown arguments, if they want to
  handle them.

- `spack test` is now a command like the others.

- `spack test` now just delegates its arguments to `pytest`, but it does
  it by receiving unknown arguments and NOT taking an explicit
  help argument.

* Fix error in fixtures.

* Improve `spack test` command a bit.

- Now supports an approximation of the old simple interface
- Also supports full pytest options if you want them.

* Use external coverage instead of pytest-cov

* Make coverage use parallel-mode.

* change __init__.py docs to include pytest

1 files changed, 141 insertions, 0 deletions

diff --git a/lib/spack/external/_pytest/AUTHORS b/lib/spack/external/_pytest/AUTHORS
new file mode 100644
index 0000000000..8c7cb19cee
--- /dev/null
+++ b/lib/spack/external/_pytest/AUTHORS
@@ -0,0 +1,141 @@
+Holger Krekel, holger at merlinux eu
+merlinux GmbH, Germany, office at merlinux eu
+
+Contributors include::
+
+Abdeali JK
+Abhijeet Kasurde
+Ahn Ki-Wook
+Alexei Kozlenok
+Anatoly Bubenkoff
+Andreas Zeidler
+Andrzej Ostrowski
+Andy Freeland
+Anthon van der Neut
+Antony Lee
+Armin Rigo
+Aron Curzon
+Aviv Palivoda
+Ben Webb
+Benjamin Peterson
+Bernard Pratz
+Bob Ippolito
+Brian Dorsey
+Brian Okken
+Brianna Laugher
+Bruno Oliveira
+Cal Leeming
+Carl Friedrich Bolz
+Charles Cloud
+Charnjit SiNGH (CCSJ)
+Chris Lamb
+Christian Boelsen
+Christian Theunert
+Christian Tismer
+Christopher Gilling
+Daniel Grana
+Daniel Hahler
+Daniel Nuri
+Daniel Wandschneider
+Danielle Jenkins
+Dave Hunt
+David Díaz-Barquero
+David Mohr
+David Vierra
+Diego Russo
+Dmitry Dygalo
+Duncan Betts
+Edison Gustavo Muenz
+Edoardo Batini
+Eduardo Schettino
+Elizaveta Shashkova
+Endre Galaczi
+Eric Hunsberger
+Eric Siegerman
+Erik M. Bray
+Feng Ma
+Florian Bruhin
+Floris Bruynooghe
+Gabriel Reis
+Georgy Dyuldin
+Graham Horler
+Greg Price
+Grig Gheorghiu
+Grigorii Eremeev (budulianin)
+Guido Wesdorp
+Harald Armin Massa
+Ian Bicking
+Jaap Broekhuizen
+Jan Balster
+Janne Vanhala
+Jason R. Coombs
+Javier Domingo Cansino
+Javier Romero
+John Towler
+Jon Sonesen
+Jordan Guymon
+Joshua Bronson
+Jurko Gospodnetić
+Justyna Janczyszyn
+Kale Kundert
+Katarzyna Jachim
+Kevin Cox
+Lee Kamentsky
+Lev Maximov
+Lukas Bednar
+Luke Murphy
+Maciek Fijalkowski
+Maho
+Marc Schlaich
+Marcin Bachry
+Mark Abramowitz
+Markus Unterwaditzer
+Martijn Faassen
+Martin K. Scherer
+Martin Prusse
+Mathieu Clabaut
+Matt Bachmann
+Matt Williams
+Matthias Hafner
+mbyt
+Michael Aquilina
+Michael Birtwell
+Michael Droettboom
+Michael Seifert
+Mike Lundy
+Ned Batchelder
+Neven Mundar
+Nicolas Delaby
+Oleg Pidsadnyi
+Oliver Bestwalter
+Omar Kohl
+Pieter Mulder
+Piotr Banaszkiewicz
+Punyashloka Biswal
+Quentin Pradet
+Ralf Schmitt
+Raphael Pierzina
+Raquel Alegre
+Roberto Polli
+Romain Dorgueil
+Roman Bolshakov
+Ronny Pfannschmidt
+Ross Lawley
+Russel Winder
+Ryan Wooden
+Samuele Pedroni
+Simon Gomizelj
+Stefan Farmbauer
+Stefan Zimmermann
+Stefano Taschini
+Steffen Allner
+Stephan Obermann
+Tareq Alayan
+Ted Xiao
+Thomas Grainger
+Tom Viner
+Trevor Bekolay
+Tyler Goodlet
+Vasily Kuznetsov
+Wouter van Ackooy
+Xuecong Liao