Factorize some tests.

Author: serhiy-storchaka

Lib/test/test_struct.py

@@ -879,27 +879,17 @@ class MyStruct(struct.Struct):
             def __new__(cls, *args, **kwargs):
                 return super().__new__(cls, '>h')
 
-        my_struct = MyStruct('>h')
-        self.assertEqual(my_struct.format, '>h')
-        self.assertEqual(my_struct.pack(12345), b'\x30\x39')
-        my_struct = MyStruct('<h')
-        self.assertEqual(my_struct.format, '>h')
-        self.assertEqual(my_struct.pack(12345), b'\x30\x39')
+        for format in '>h', '<h', 42, '$', '\u20ac':
+            with self.subTest(format=format):
+                my_struct = MyStruct(format)
+                self.assertEqual(my_struct.format, '>h')
+                self.assertEqual(my_struct.pack(12345), b'\x30\x39')
         my_struct = MyStruct(format='<h')
         self.assertEqual(my_struct.format, '>h')
         self.assertEqual(my_struct.pack(12345), b'\x30\x39')
         my_struct = MyStruct()
         self.assertEqual(my_struct.format, '>h')
         self.assertEqual(my_struct.pack(12345), b'\x30\x39')
-        my_struct = MyStruct(42)
-        self.assertEqual(my_struct.format, '>h')
-        self.assertEqual(my_struct.pack(12345), b'\x30\x39')
-        my_struct = MyStruct('$')
-        self.assertEqual(my_struct.format, '>h')
-        self.assertEqual(my_struct.pack(12345), b'\x30\x39')
-        my_struct = MyStruct('\u20ac')
-        self.assertEqual(my_struct.format, '>h')
-        self.assertEqual(my_struct.pack(12345), b'\x30\x39')
         my_struct = MyStruct('<h', 42)
         self.assertEqual(my_struct.format, '>h')
         self.assertEqual(my_struct.pack(12345), b'\x30\x39')