diff --git a/lib/spack/spack/cmd/__init__.py b/lib/spack/spack/cmd/__init__.py
index b1e174930b7..5cee932504b 100644
--- a/lib/spack/spack/cmd/__init__.py
+++ b/lib/spack/spack/cmd/__init__.py
@@ -171,7 +171,9 @@ def quote_kvp(string: str) -> str:
 
 
 def parse_specs(
-    args: Union[str, List[str]], concretize: bool = False, tests: bool = False
+    args: Union[str, List[str]],
+    concretize: bool = False,
+    tests: spack.concretize.TestsType = False,
 ) -> List[spack.spec.Spec]:
     """Convenience function for parsing arguments from specs.  Handles common
     exceptions and dies if there are errors.
@@ -183,11 +185,13 @@ def parse_specs(
     if not concretize:
         return specs
 
-    to_concretize = [(s, None) for s in specs]
+    to_concretize: List[spack.concretize.SpecPairInput] = [(s, None) for s in specs]
     return _concretize_spec_pairs(to_concretize, tests=tests)
 
 
-def _concretize_spec_pairs(to_concretize, tests=False):
+def _concretize_spec_pairs(
+    to_concretize: List[spack.concretize.SpecPairInput], tests: spack.concretize.TestsType = False
+) -> List[spack.spec.Spec]:
     """Helper method that concretizes abstract specs from a list of abstract,concrete pairs.
 
     Any spec with a concrete spec associated with it will concretize to that spec. Any spec
@@ -198,7 +202,7 @@ def _concretize_spec_pairs(to_concretize, tests=False):
     # Special case for concretizing a single spec
     if len(to_concretize) == 1:
         abstract, concrete = to_concretize[0]
-        return [concrete or abstract.concretized()]
+        return [concrete or abstract.concretized(tests=tests)]
 
     # Special case if every spec is either concrete or has an abstract hash
     if all(
diff --git a/lib/spack/spack/concretize.py b/lib/spack/spack/concretize.py
index 89180d5e7fb..468e0309ecf 100644
--- a/lib/spack/spack/concretize.py
+++ b/lib/spack/spack/concretize.py
@@ -5,7 +5,7 @@
 import sys
 import time
 from contextlib import contextmanager
-from typing import Iterable, Optional, Sequence, Tuple, Union
+from typing import Iterable, List, Optional, Sequence, Tuple, Union
 
 import llnl.util.tty as tty
 
@@ -35,6 +35,7 @@ def enable_compiler_existence_check():
     CHECK_COMPILER_EXISTENCE = saved
 
 
+SpecPairInput = Tuple[Spec, Optional[Spec]]
 SpecPair = Tuple[Spec, Spec]
 SpecLike = Union[Spec, str]
 TestsType = Union[bool, Iterable[str]]
@@ -59,8 +60,8 @@ def concretize_specs_together(
 
 
 def concretize_together(
-    spec_list: Sequence[SpecPair], tests: TestsType = False
-) -> Sequence[SpecPair]:
+    spec_list: Sequence[SpecPairInput], tests: TestsType = False
+) -> List[SpecPair]:
     """Given a number of specs as input, tries to concretize them together.
 
     Args:
@@ -76,8 +77,8 @@ def concretize_together(
 
 
 def concretize_together_when_possible(
-    spec_list: Sequence[SpecPair], tests: TestsType = False
-) -> Sequence[SpecPair]:
+    spec_list: Sequence[SpecPairInput], tests: TestsType = False
+) -> List[SpecPair]:
     """Given a number of specs as input, tries to concretize them together to the extent possible.
 
     See documentation for ``unify: when_possible`` concretization for the precise definition of
@@ -113,8 +114,8 @@ def concretize_together_when_possible(
 
 
 def concretize_separately(
-    spec_list: Sequence[SpecPair], tests: TestsType = False
-) -> Sequence[SpecPair]:
+    spec_list: Sequence[SpecPairInput], tests: TestsType = False
+) -> List[SpecPair]:
     """Concretizes the input specs separately from each other.
 
     Args: