State what the refresh tests verify

This adds short docstrings to each of the four refresh tests to
briefly state the claims they verify.

Author: EliahKagan

test/test_git.py

@@ -315,6 +315,7 @@ def test_cmd_override(self):
             self.assertRaises(GitCommandNotFound, self.git.version)
 
     def test_refresh_bad_absolute_git_path(self):
+        """Bad absolute path arg is reported and not set."""
         absolute_path = str(Path("yada").absolute())
         expected_pattern = rf"\n[ \t]*cmdline: {re.escape(absolute_path)}\Z"
 
@@ -324,6 +325,7 @@ def test_refresh_bad_absolute_git_path(self):
             self.assertEqual(self.git.GIT_PYTHON_GIT_EXECUTABLE, old_git_executable)
 
     def test_refresh_bad_relative_git_path(self):
+        """Bad relative path arg is resolved to absolute path and reported, not set."""
         absolute_path = str(Path("yada").absolute())
         expected_pattern = rf"\n[ \t]*cmdline: {re.escape(absolute_path)}\Z"
 
@@ -333,13 +335,15 @@ def test_refresh_bad_relative_git_path(self):
             self.assertEqual(self.git.GIT_PYTHON_GIT_EXECUTABLE, old_git_executable)
 
     def test_refresh_good_absolute_git_path(self):
+        """Good absolute path arg is set."""
         absolute_path = shutil.which("git")
 
         with _rollback_refresh():
             refresh(absolute_path)
             self.assertEqual(self.git.GIT_PYTHON_GIT_EXECUTABLE, absolute_path)
 
     def test_refresh_good_relative_git_path(self):
+        """Good relative path arg is resolved to absolute path and set."""
         absolute_path = shutil.which("git")
         dirname, basename = osp.split(absolute_path)