Make tests use mock compiler configuration.

- makes sure tests don't fail on systems that don't have some compilers (e.g. clang).
- more control over specific test cases for compilers.

lib/spack/spack/__init__.py

@@ -64,10 +64,14 @@
 db = PackageDB(packages_path)
 
 #
-# This is the path to mock packages used by spack for testing.
+# Paths to mock files for testing.
 #
 mock_packages_path = join_path(var_path, "mock_packages")
 
+mock_config_path = join_path(var_path, "mock_configs")
+mock_site_config = join_path(mock_config_path, "site_spackconfig")
+mock_user_config = join_path(mock_config_path, "user_spackconfig")
+
 #
 # This controls how spack lays out install prefixes and
 # stage directories.

lib/spack/spack/test/mock_packages_test.py

@@ -25,9 +25,11 @@
 import unittest
 
 import spack
+import spack.config
 from spack.packages import PackageDB
 from spack.spec import Spec
 
+
 def set_pkg_dep(pkg, spec):
     """Alters dependence information for a pacakge.
        Use this to mock up constraints.
@@ -45,9 +47,14 @@ def setUp(self):
         self.real_db = spack.db
         spack.db = PackageDB(spack.mock_packages_path)
 
+        self.real_scopes = spack.config._scopes
+        spack.config._scopes = {
+            'site' : spack.mock_site_config,
+            'user' : spack.mock_user_config }
 
     @classmethod
     def tearDown(self):
         """Restore the real packages path after any test."""
-        #restore_dependencies()
         spack.db = self.real_db
+        spack.config._scopes = self.real_scopes
+