Convert test_global, test_scope and test_grammar to unittest.

I tried to enclose all tests which must be run at the toplevel
(instead of inside a method) in exec statements.

Lib/test/test_global.py

@@ -1,51 +1,51 @@
 """Verify that warnings are issued for global statements following use."""
 
-from test.test_support import check_syntax
+from test.test_support import run_unittest, check_syntax_error
+import unittest
 
 import warnings
+warnings.filterwarnings("error", module="<test string>")
 
-warnings.filterwarnings("error", module="<test code>")
+class GlobalTests(unittest.TestCase):
 
-def compile_and_check(text, should_fail=1):
-    try:
-        compile(text, "<test code>", "exec")
-    except SyntaxError, msg:
-        if should_fail:
-            print "got SyntaxError as expected"
-        else:
-            print "raised unexpected SyntaxError:", text
-    else:
-        if should_fail:
-            print "should have raised SyntaxError:", text
-        else:
-            print "as expected, no SyntaxError"
-
-prog_text_1 = """
+    def test1(self):
+        prog_text_1 = """\
 def wrong1():
     a = 1
     b = 2
     global a
     global b
 """
-compile_and_check(prog_text_1)
+        check_syntax_error(self, prog_text_1)
 
-prog_text_2 = """
+    def test2(self):
+        prog_text_2 = """\
 def wrong2():
     print x
     global x
 """
-compile_and_check(prog_text_2)
+        check_syntax_error(self, prog_text_2)
 
-prog_text_3 = """
+    def test3(self):
+        prog_text_3 = """\
 def wrong3():
     print x
     x = 2
     global x
 """
-compile_and_check(prog_text_3)
+        check_syntax_error(self, prog_text_3)
 
-prog_text_4 = """
+    def test4(self):
+        prog_text_4 = """\
 global x
 x = 2
 """
-compile_and_check(prog_text_4, 0)
+        # this should work
+        compile(prog_text_4, "<test string>", "exec")
+
+
+def test_main():
+    run_unittest(GlobalTests)
+
+if __name__ == "__main__":
+    test_main()