fix: change news item and test docstring.

Author: stevenhua0320

news/deprecate-assignUniqueLabels.rst

@@ -1,14 +1,14 @@
 **Added:**
 
-* No News Added: deprecate assignUniqueLabels method
+* Added `diffpy.structure.Structure.assign_unique_labels` in replace of `assignUniqueLabels`
 
 **Changed:**
 
 * <news item>
 
 **Deprecated:**
 
-* <news item>
+* Deprecated `diffpy.structure.Structure.assignUniqueLabels` for removal in 4.0.0
 
 **Removed:**
 

tests/test_structure.py

@@ -121,18 +121,15 @@ def test___copy__(self):
     #     return
 
     def test_assignUniqueLabels(self):
-        """Duplicate test with the deprecated assignUniqueLabels method.
-
-        Remove this test in version 4.0.0
-        """
+        """Check Structure.assignUniqueLabels()"""
         self.assertEqual("", "".join([a.label for a in self.stru]))
         self.stru.assignUniqueLabels()
         self.assertEqual("C1", self.stru[0].label)
         self.assertEqual("C2", self.stru[1].label)
         return
 
     def test_assign_unique_labels(self):
-        """Check Structure.assignUniqueLabels()"""
+        """Check Structure.assign_unique_labels()"""
         self.assertEqual("", "".join([a.label for a in self.stru]))
         self.stru.assign_unique_labels()
         self.assertEqual("C1", self.stru[0].label)