diff --git a/lib/spack/spack/test/spec_semantics.py b/lib/spack/spack/test/spec_semantics.py
index 4ed7c635e9..2c7c1d22ed 100644
--- a/lib/spack/spack/test/spec_semantics.py
+++ b/lib/spack/spack/test/spec_semantics.py
@@ -707,3 +707,14 @@ def test_constrain_dependency_not_changed(self):
         check_constrain_not_changed(
             'libelf^foo target=' + default_target,
             'libelf^foo target=' + default_target)
+
+    def test_exceptional_paths_for_constructor(self):
+
+        with pytest.raises(TypeError):
+            Spec((1, 2))
+
+        with pytest.raises(ValueError):
+            Spec('')
+
+        with pytest.raises(ValueError):
+            Spec('libelf foo')