Update test to use context manager for StringIO

Author: willwray

tests/issue0079.py

@@ -12,17 +12,17 @@ def runTest(self):
 
         p = Preprocessor()
         p.parse(self.input)
-        oh = StringIO()
-        p.write(oh)
-        print("ok")
-        if oh.getvalue() != self.output:
-            print("Should be:\n" + self.output + "EOF\n", file = sys.stderr)
-            print("\nWas:\n" + oh.getvalue()+"EOF\n", file = sys.stderr)
-        self.assertEqual(p.return_code, 0)
-        self.assertEqual(oh.getvalue(), self.output)
+        with StringIO() as oh:
+            p.write(oh)
+            print("ok")
+            if oh.getvalue() != self.output:
+                print("Should be:\n" + self.output + "EOF\n", file = sys.stderr)
+                print("\nWas:\n" + oh.getvalue()+"EOF\n", file = sys.stderr)
+            self.assertEqual(p.return_code, 0)
+            self.assertEqual(oh.getvalue(), self.output)
 
 class pp_number_pasting(unittest.TestCase, runner):
-    input = r"""#define CAT_(A,B)A##B
+    input = """#define CAT_(A,B)A##B
 #define CAT(A,B)CAT_(A,B)
 #define Ox 0x
 #if CAT(Ox,1)
@@ -31,7 +31,7 @@ class pp_number_pasting(unittest.TestCase, runner):
 PP_NUMBER paste fail
 #endif
 """
-    output = r"""
+    output = """