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, 71 insertions, 0 deletions

diff --git a/lib/spack/external/_pytest/nose.py b/lib/spack/external/_pytest/nose.py
new file mode 100644
index 0000000000..0387468686
--- /dev/null
+++ b/lib/spack/external/_pytest/nose.py
@@ -0,0 +1,71 @@
+""" run test suites written for nose. """
+
+import sys
+
+import py
+import pytest
+from _pytest import unittest
+
+
+def get_skip_exceptions():
+    skip_classes = set()
+    for module_name in ('unittest', 'unittest2', 'nose'):
+        mod = sys.modules.get(module_name)
+        if hasattr(mod, 'SkipTest'):
+            skip_classes.add(mod.SkipTest)
+    return tuple(skip_classes)
+
+
+def pytest_runtest_makereport(item, call):
+    if call.excinfo and call.excinfo.errisinstance(get_skip_exceptions()):
+        # let's substitute the excinfo with a pytest.skip one
+        call2 = call.__class__(lambda:
+                    pytest.skip(str(call.excinfo.value)), call.when)
+        call.excinfo = call2.excinfo
+
+
+@pytest.hookimpl(trylast=True)
+def pytest_runtest_setup(item):
+    if is_potential_nosetest(item):
+        if isinstance(item.parent, pytest.Generator):
+            gen = item.parent
+            if not hasattr(gen, '_nosegensetup'):
+                call_optional(gen.obj, 'setup')
+                if isinstance(gen.parent, pytest.Instance):
+                    call_optional(gen.parent.obj, 'setup')
+                gen._nosegensetup = True
+        if not call_optional(item.obj, 'setup'):
+            # call module level setup if there is no object level one
+            call_optional(item.parent.obj, 'setup')
+        #XXX this implies we only call teardown when setup worked
+        item.session._setupstate.addfinalizer((lambda: teardown_nose(item)), item)
+
+def teardown_nose(item):
+    if is_potential_nosetest(item):
+        if not call_optional(item.obj, 'teardown'):
+            call_optional(item.parent.obj, 'teardown')
+        #if hasattr(item.parent, '_nosegensetup'):
+        #    #call_optional(item._nosegensetup, 'teardown')
+        #    del item.parent._nosegensetup
+
+
+def pytest_make_collect_report(collector):
+    if isinstance(collector, pytest.Generator):
+        call_optional(collector.obj, 'setup')
+
+
+def is_potential_nosetest(item):
+    # extra check needed since we do not do nose style setup/teardown
+    # on direct unittest style classes
+    return isinstance(item, pytest.Function) and \
+        not isinstance(item, unittest.TestCaseFunction)
+
+
+def call_optional(obj, name):
+    method = getattr(obj, name, None)
+    isfixture = hasattr(method, "_pytestfixturefunction")
+    if method is not None and not isfixture and py.builtin.callable(method):
+        # If there's any problems allow the exception to raise rather than
+        # silently ignoring them
+        method()
+        return True