diff --git a/lib/spack/spack/test/compilers/conversion.py b/lib/spack/spack/test/compilers/conversion.py
index d9312c55b18..82a1f595ef1 100644
--- a/lib/spack/spack/test/compilers/conversion.py
+++ b/lib/spack/spack/test/compilers/conversion.py
@@ -6,6 +6,8 @@
 
 from spack.compilers.config import CompilerFactory
 
+pytestmark = [pytest.mark.usefixtures("config", "mock_packages")]
+
 
 @pytest.fixture()
 def mock_compiler(mock_executable):
@@ -55,7 +57,7 @@ def test_compiler_conversion_with_flags(mock_compiler):
     assert compiler_spec.extra_attributes["flags"]["cxxflags"] == "-O2 -g"
 
 
-def tests_compiler_conversion_with_environment(mock_compiler):
+def test_compiler_conversion_with_environment(mock_compiler):
     """Tests that custom environment modifications are converted appropriately
     for external compilers
     """
@@ -67,7 +69,7 @@ def tests_compiler_conversion_with_environment(mock_compiler):
     assert compiler_spec.extra_attributes["environment"] == mods
 
 
-def tests_compiler_conversion_extra_rpaths(mock_compiler):
+def test_compiler_conversion_extra_rpaths(mock_compiler):
     """Tests that extra rpaths are converted appropriately for external compilers"""
     mock_compiler["extra_rpaths"] = ["/foo/bar"]
     compiler_spec = CompilerFactory.from_legacy_yaml(mock_compiler)[0]
@@ -76,7 +78,7 @@ def tests_compiler_conversion_extra_rpaths(mock_compiler):
     assert compiler_spec.extra_attributes["extra_rpaths"] == ["/foo/bar"]
 
 
-def tests_compiler_conversion_modules(mock_compiler):
+def test_compiler_conversion_modules(mock_compiler):
     """Tests that modules are converted appropriately for external compilers"""
     modules = ["foo/4.1.2", "bar/5.1.4"]
     mock_compiler["modules"] = modules
@@ -86,7 +88,7 @@ def tests_compiler_conversion_modules(mock_compiler):
 
 
 @pytest.mark.regression("49717")
-def tests_compiler_conversion_corrupted_paths(mock_compiler):
+def test_compiler_conversion_corrupted_paths(mock_compiler):
     """Tests that compiler entries with corrupted path do not raise"""
     mock_compiler["paths"] = {"cc": "gcc", "cxx": "g++", "fc": "gfortran", "f77": "gfortran"}
     # Test this call doesn't raise
diff --git a/var/spack/test_repos/builtin.mock/packages/gcc/package.py b/var/spack/test_repos/builtin.mock/packages/gcc/package.py
index 77c789a92d9..17ddd67bbb3 100644
--- a/var/spack/test_repos/builtin.mock/packages/gcc/package.py
+++ b/var/spack/test_repos/builtin.mock/packages/gcc/package.py
@@ -31,6 +31,7 @@ class Gcc(CompilerPackage, Package):
     provides("fortran", when="languages=fortran")
 
     depends_on("c", type="build")
+    depends_on("cxx", type="build")
 
     c_names = ["gcc"]
     cxx_names = ["g++"]
@@ -48,6 +49,19 @@ class Gcc(CompilerPackage, Package):
         "fortran": os.path.join("gcc", "gfortran"),
     }
 
+    implicit_rpath_libs = ["libgcc", "libgfortran"]
+
+    @classmethod
+    def determine_variants(cls, exes, version_str):
+        compilers = cls.determine_compiler_paths(exes=exes)
+
+        languages = set()
+        translation = {"cxx": "c++"}
+        for lang, compiler in compilers.items():
+            languages.add(translation.get(lang, lang))
+        variant_str = "languages={0}".format(",".join(languages))
+        return variant_str, {"compilers": compilers}
+
     def install(self, spec, prefix):
         # Create the minimal compiler that will fool `spack compiler find`
         mkdirp(prefix.bin)