Add syntax error offset tests

Author: bswck

Lib/test/test_exceptions.py

@@ -252,7 +252,16 @@ def testSyntaxErrorOffset(self):
         check('[\nfile\nfor str(file)\nin\n[]\n]', 3, 5)
         check('[file for\n str(file) in []]', 2, 2)
         check("ages = {'Alice'=22, 'Bob'=23}", 1, 9)
-        check('match ...:\n    case {**rest, "key": value}:\n        ...', 2, 19)
+        check(dedent("""\
+          match ...:
+            case {**rest1, "after": after}:
+              ...
+        """), 2, 11)
+        check(dedent("""\
+          match ...:
+            case {"before": before, **rest2, "after": after}:
+              ...
+        """), 2, 29)
         check("[a b c d e f]", 1, 2)
         check("for x yfff:", 1, 7)
         check("f(a for a in b, c)", 1, 3, 1, 15)