StringProcessing: position_is_escaped() test

Adds a test that uses the class defined test-strings. The old test only
uses a custom single test string.

Fixes #464.

coalib/tests/parsing/StringProcessingTest.py

@@ -1184,6 +1184,38 @@ def test_position_is_escaped(self):
         for position, value in result_dict.items():
             self.assertEqual(position_is_escaped(test_string, position), value)
 
+    # Test the position_is_escaped() with more test strings from this class.
+    def test_position_is_escaped_advanced(self):
+        expected_results = [
+            30 * [False] + [True] + 7 * [False],
+            30 * [False] + [True] + 7 * [False],
+            30 * [False] + [True] + 7 * [False],
+            28 * [False] + [True, False, True] + 7 * [False],
+            31 * [False] + [True] + 6 * [False],
+            31 * [False] + [True] + 6 * [False],
+            38 * [False],
+            6 * [False] + [True] + 31 * [False],
+            6 * [False] + [True, False, True] + 29 * [False],
+            6 * [False] + [True] + 31 * [False],
+            6 * [False] + [True, False, True] + 29 * [False],
+            14 * [False] + [True] + 23 * [False],
+            12 * [False] + [True, False, True] + 23 * [False],
+            38 * [False],
+            [],
+            14 * [False],
+            [False],
+            [False, True]]
+
+        results = [[position_is_escaped(test_string, i)
+                    for i in range(len(test_string))]
+                   for test_string in self.test_strings]
+
+        zipped = [zip(x, y) for x, y in zip(expected_results, results)]
+        flattened = [item for sublist in zipped for item in sublist]
+
+        for elem in flattened:
+            self.assertEqual(elem[0], elem[1])
+
 if __name__ == '__main__':
     unittest.main(verbosity=2)