Testing: fix unintended interactions between tests, part 2 (#16429)

This fixes some errors with setting up test configuration. These
errors do not cause current Spack tests to fail but do create
red herring issues elsewhere (see #15666). Fixing these errors
leads to more errors in tests that depended on the original
misconfigured state, so those are also addressed here.

This is an update to #16003 which accounts for some unit tests with
conflicting config/mutable_config fixtures. These conflicts were
not exposed until the mutable_config fixture was fixed. Details are
included below. The change which builds on #16003 is prefixed with
"(new)".

* For tests that use the real Spack package repository, the config
  needs to avoid using MPI providers that are not intended to be
  installed by Spack. Without this, it is possible that Spack tests
  which concretize the MPI virtual will end up trying to use an
  implementation that it shouldn't (e.g. one that is always
  provided externally). See #15666 for an example.
* The mutable_config test fixture was not initializing the scope
  roots to the right directories (so the resulting config was empty).
* The current_host fixture in the concretize.py tests was using the
  config fixture rather than mutable_config, and was polluting the
  config cache for other tests.
* One test in concretize.py was clearing a nonexistent cache
  (PackagePrefs._packages_config_cache). This reference has been
  removed.
* The test 'test_preferred_compilers' was was depending on cross
  test config pollution to succeed. The initial spec before
  concretization has been updated to updated to be explicit about
  the desired result.
* (new) For tests that use install_mockery and mutable_config,
  replace install_mockery with a separate install_mockery_mutable_config
  fixture that is exactly the same as install_mockery but uses the
  mutable_config fixture to avoid conflicts.

6 files changed, 47 insertions, 12 deletions

diff --git a/lib/spack/spack/cmd/compiler.py b/lib/spack/spack/cmd/compiler.py
index 625466f8c7..c8f52af04d 100644
--- a/lib/spack/spack/cmd/compiler.py
+++ b/lib/spack/spack/cmd/compiler.py
@@ -159,7 +159,19 @@ def compiler_list(args):
     tty.msg("Available compilers")
     index = index_by(spack.compilers.all_compilers(scope=args.scope),
                      lambda c: (c.spec.name, c.operating_system, c.target))
-    ordered_sections = sorted(index.items(), key=lambda item: item[0])
+
+    # For a container, take each element which does not evaluate to false and
+    # convert it to a string. For elements which evaluate to False (e.g. None)
+    # convert them to '' (in which case it still evaluates to False but is a
+    # string type). Tuples produced by this are guaranteed to be comparable in
+    # Python 3
+    convert_str = (
+        lambda tuple_container:
+        tuple(str(x) if x else '' for x in tuple_container))
+
+    index_str_keys = list(
+        (convert_str(x), y) for x, y in index.items())
+    ordered_sections = sorted(index_str_keys, key=lambda item: item[0])
     for i, (key, compilers) in enumerate(ordered_sections):
         if i >= 1:
             print()
diff --git a/lib/spack/spack/test/cmd/install.py b/lib/spack/spack/test/cmd/install.py
index dd52cea406..4a5db55c01 100644
--- a/lib/spack/spack/test/cmd/install.py
+++ b/lib/spack/spack/test/cmd/install.py
@@ -722,8 +722,8 @@ def test_cdash_auth_token(tmpdir, install_mockery, capfd):
 
 
 def test_compiler_bootstrap(
-        install_mockery, mock_packages, mock_fetch, mock_archive,
-        mutable_config, monkeypatch):
+        install_mockery_mutable_config, mock_packages, mock_fetch,
+        mock_archive, mutable_config, monkeypatch):
     monkeypatch.setattr(spack.concretize.Concretizer,
                         'check_for_compiler_existence', False)
     spack.config.set('config:install_missing_compilers', True)
@@ -735,8 +735,8 @@ def test_compiler_bootstrap(
 
 @pytest.mark.regression('16221')
 def test_compiler_bootstrap_already_installed(
-        install_mockery, mock_packages, mock_fetch, mock_archive,
-        mutable_config, monkeypatch):
+        install_mockery_mutable_config, mock_packages, mock_fetch,
+        mock_archive, mutable_config, monkeypatch):
     monkeypatch.setattr(spack.concretize.Concretizer,
                         'check_for_compiler_existence', False)
     spack.config.set('config:install_missing_compilers', True)
diff --git a/lib/spack/spack/test/concretize.py b/lib/spack/spack/test/concretize.py
index 232dfaeb4b..ec594e4088 100644
--- a/lib/spack/spack/test/concretize.py
+++ b/lib/spack/spack/test/concretize.py
@@ -12,7 +12,6 @@ import spack.repo
 
 from spack.concretize import find_spec, NoValidVersionError
 from spack.error import SpecError
-from spack.package_prefs import PackagePrefs
 from spack.spec import Spec, CompilerSpec, ConflictsInSpecError
 from spack.version import ver
 from spack.util.mock_package import MockPackageMultiRepo
@@ -103,8 +102,6 @@ def current_host(request, monkeypatch):
         monkeypatch.setattr(spack.platforms.test.Test, 'default', cpu)
         yield target
     else:
-        # There's a cache that needs to be cleared for unit tests
-        PackagePrefs._packages_config_cache = None
         with spack.config.override('packages:all', {'target': [cpu]}):
             yield target
 
@@ -112,7 +109,10 @@ def current_host(request, monkeypatch):
     spack.architecture.get_platform.cache.clear()
 
 
-@pytest.mark.usefixtures('config', 'mock_packages')
+# This must use the mutable_config fixture because the test
+# adjusting_default_target_based_on_compiler uses the current_host fixture,
+# which changes the config.
+@pytest.mark.usefixtures('mutable_config', 'mock_packages')
 class TestConcretize(object):
     def test_concretize(self, spec):
         check_concretize(spec)
diff --git a/lib/spack/spack/test/concretize_preferences.py b/lib/spack/spack/test/concretize_preferences.py
index 922d5a11d8..ca4df6700c 100644
--- a/lib/spack/spack/test/concretize_preferences.py
+++ b/lib/spack/spack/test/concretize_preferences.py
@@ -100,7 +100,7 @@ class TestConcretizePreferences(object):
         # Try the last available compiler
         compiler = str(compiler_list[-1])
         update_packages('mpileaks', 'compiler', [compiler])
-        spec = concretize('mpileaks')
+        spec = concretize('mpileaks os=redhat6 target=x86')
         assert spec.compiler == spack.spec.CompilerSpec(compiler)
 
     def test_preferred_target(self, mutable_mock_repo):
diff --git a/lib/spack/spack/test/conftest.py b/lib/spack/spack/test/conftest.py
index 736c5a5563..ae8fa80ab7 100644
--- a/lib/spack/spack/test/conftest.py
+++ b/lib/spack/spack/test/conftest.py
@@ -423,13 +423,13 @@ def config(mock_configuration):
 
 
 @pytest.fixture(scope='function')
-def mutable_config(tmpdir_factory, configuration_dir, monkeypatch):
+def mutable_config(tmpdir_factory, configuration_dir):
     """Like config, but tests can modify the configuration."""
     mutable_dir = tmpdir_factory.mktemp('mutable_config').join('tmp')
     configuration_dir.copy(mutable_dir)
 
     cfg = spack.config.Configuration(
-        *[spack.config.ConfigScope(name, str(mutable_dir))
+        *[spack.config.ConfigScope(name, str(mutable_dir.join(name)))
           for name in ['site', 'system', 'user']])
 
     with use_configuration(cfg):
@@ -602,6 +602,26 @@ def install_mockery(tmpdir, config, mock_packages, monkeypatch):
     spack.store.store = real_store
 
 
+@pytest.fixture(scope='function')
+def install_mockery_mutable_config(
+        tmpdir, mutable_config, mock_packages, monkeypatch):
+    """Hooks a fake install directory, DB, and stage directory into Spack.
+
+    This is specifically for tests which want to use 'install_mockery' but
+    also need to modify configuration (and hence would want to use
+    'mutable config'): 'install_mockery' does not support this.
+    """
+    real_store = spack.store.store
+    spack.store.store = spack.store.Store(str(tmpdir.join('opt')))
+
+    # We use a fake package, so temporarily disable checksumming
+    with spack.config.override('config:checksum', False):
+        yield
+
+    tmpdir.join('opt').remove()
+    spack.store.store = real_store
+
+
 @pytest.fixture()
 def mock_fetch(mock_archive):
     """Fake the URL for a package so it downloads from a file."""
diff --git a/lib/spack/spack/test/data/config/packages.yaml b/lib/spack/spack/test/data/config/packages.yaml
index c7256ddb33..63e63e525d 100644
--- a/lib/spack/spack/test/data/config/packages.yaml
+++ b/lib/spack/spack/test/data/config/packages.yaml
@@ -1,4 +1,7 @@
 packages:
+  all:
+    providers:
+      mpi: [openmpi, mpich]
   externaltool:
     buildable: False
     paths: