Minor tweak to a test docstring (#41985)

* Minor tweak to a test docstring

Shorten the description of a fixture, extend the description
of the test where it's used.

* Fix typo

lib/spack/spack/test/concretize.py

@@ -134,12 +134,7 @@ def current_host(request, monkeypatch):
 
 @pytest.fixture(scope="function", params=[True, False])
 def fuzz_dep_order(request, monkeypatch):
-    """Metafunction that tweaks the order of iteration over dependencies in the concretizer.
-
-    The original concretizer can be sensitive to this, so we use this to ensure that it
-    is tested forwards and backwards.
-
-    """
+    """Meta-function that tweaks the order of iteration over dependencies in a package."""
 
     def reverser(pkg_name):
         if request.param:
@@ -914,6 +909,12 @@ def test_conditional_variants_fail(self, bad_spec):
         ],
     )
     def test_conditional_dependencies(self, spec_str, expected, unexpected, fuzz_dep_order):
+        """Tests that conditional dependencies are correctly attached.
+
+        The original concretizer can be sensitive to the iteration order over the dependencies of
+        a package, so we use a fuzzer function to test concretization with dependencies iterated
+        forwards and backwards.
+        """
         fuzz_dep_order("py-extension3")  # test forwards and backwards
 
         s = Spec(spec_str).concretized()