Github actions: add CI for ASP based solver

.github/workflows/linux_unit_tests.yaml

@@ -117,3 +117,24 @@ jobs:
           git fetch origin ${{ github.ref }}:test-branch
           git checkout test-branch
           share/spack/qa/run-unit-tests
+  clingo:
+    # Test for the clingo based solver
+    runs-on: ubuntu-latest
+    container: spack/github-actions:clingo
+    steps:
+      - name: Run unit tests
+        run: |
+          whoami && echo PWD=$PWD && echo HOME=$HOME && echo SPACK_TEST_SOLVER=$SPACK_TEST_SOLVER
+          which clingo && clingo --version
+          git clone https://github.com/spack/spack.git && cd spack
+          git fetch origin ${{ github.ref }}:test-branch
+          git checkout test-branch
+          . share/spack/setup-env.sh
+          spack compiler find
+          spack solve mpileaks%gcc
+          coverage run $(which spack) test -v
+          coverage combine
+          coverage xml
+      - uses: codecov/codecov-action@v1
+        with:
+          flags: unittests,linux,clingo

lib/spack/spack/test/cmd/buildcache.py

@@ -125,6 +125,10 @@ def test_buildcache_create_fails_on_noargs(tmpdir):
         buildcache('create', '-d', str(tmpdir), '--unsigned')
 
 
+@pytest.mark.skipif(
+    os.environ.get('SPACK_TEST_SOLVER') == 'clingo',
+    reason='Test for Clingo are run in a container with root permissions'
+)
 def test_buildcache_create_fail_on_perm_denied(
         install_mockery, mock_fetch, monkeypatch, tmpdir):
     """Ensure that buildcache create fails on permission denied error."""

lib/spack/spack/test/database.py

@@ -648,6 +648,10 @@ def test_090_non_root_ref_counts(mutable_database):
     assert mpich_rec.ref_count == 0
 
 
+@pytest.mark.skipif(
+    os.environ.get('SPACK_TEST_SOLVER') == 'clingo',
+    reason='Test for Clingo are run in a container with root permissions'
+)
 def test_100_no_write_with_exception_on_remove(database):
     def fail_while_writing():
         with database.write_transaction():
@@ -665,6 +669,10 @@ def fail_while_writing():
         assert len(database.query('mpileaks ^zmpi', installed=any)) == 1
 
 
+@pytest.mark.skipif(
+    os.environ.get('SPACK_TEST_SOLVER') == 'clingo',
+    reason='Test for Clingo are run in a container with root permissions'
+)
 def test_110_no_write_with_exception_on_install(database):
     def fail_while_writing():
         with database.write_transaction():

lib/spack/spack/test/llnl/util/lock.py

@@ -661,6 +661,10 @@ def test_upgrade_read_to_write(private_lock_path):
     assert lock._file is None
 
 
+@pytest.mark.skipif(
+    os.environ.get('SPACK_TEST_SOLVER') == 'clingo',
+    reason='Test for Clingo are run in a container with root permissions'
+)
 def test_upgrade_read_to_write_fails_with_readonly_file(private_lock_path):
     """Test that read-only file can be read-locked but not write-locked."""
     # ensure lock file exists the first time