[sgf-parsing] fix escaped characters (exercism#2181)

yawpitch · web-flow · commit 1192f536fba2 · 2020-02-25T10:48:19.000-05:00
Fixes issue with pytest throwing a warning on invalid escapes. Closes exercism#2176
diff --git a/bin/generate_tests.py b/bin/generate_tests.py
@@ -101,6 +101,47 @@ def parse_datetime(string, strip_module=False):
         return result.replace("datetime.", "", 1)
     return result
 
+INVALID_ESCAPE_RE = re.compile(
+    r"""
+    \\(?!                           # a backslash NOT followed by
+        newline                     # the literal newline
+    |[                              # OR precisely one of
+        \\                          # another backslash
+        '                           # the single quote
+        "                           # the double quote
+        a                           # the ASCII bell
+        b                           # the ASCII backspace
+        f                           # the ASCII formfeed
+        n                           # the ASCII linefeed
+        r                           # the ASCII carriage return
+        t                           # the ASCII horizontal tab
+        v                           # the ASCII vertical tab
+    ]|                              # OR
+        o(?:[0-8]{1,3})             # an octal value
+    |                               # OR
+        x(?:[0-9A-Fa-f]{2})         # a hexidecimal value
+    |                               # OR
+        N                           # a unicode char name composed of
+        \{                          # an opening brace
+            [A-Z][A-Z\ \-]*[A-Z]    # uppercase WORD, WORDs (or WORD-WORDs)
+        \}                          # and a closing brace
+    |                               # OR
+        u(?:[0-9A-Fa-f]{4})         # a 16-bit unicode char
+    |                               # OR
+        U(?:[0-9A-Fa-f]{8})         # a 32-bit unicode char
+    )""", flags=re.VERBOSE)
+
+def escape_invalid_escapes(string):
+    """
+    Some canonical data includes invalid escape sequences, which
+    need to be properly escaped before template render.
+    """
+    return INVALID_ESCAPE_RE.sub(r"\\\\", string)
+
+ALL_VALID = r"\newline\\\'\"\a\b\f\n\r\t\v\o123" \
+            r"\xFF\N{GREATER-THAN SIGN}\u0394\U00000394"
+
+assert ALL_VALID == escape_invalid_escapes(ALL_VALID)
 
 def get_tested_properties(spec):
     """
@@ -291,6 +332,7 @@ def generate(
     env.filters["regex_split"] = regex_split
     env.filters["zip"] = zip
     env.filters["parse_datetime"] = parse_datetime
+    env.filters["escape_invalid_escapes"] = escape_invalid_escapes
     env.tests["error_case"] = error_case
     result = True
     for exercise in sorted(glob(os.path.join("exercises", exercise_glob))):
diff --git a/exercises/sgf-parsing/.meta/template.j2 b/exercises/sgf-parsing/.meta/template.j2
@@ -2,7 +2,7 @@
 
 {% macro test_case(case) -%}
     def test_{{ case["description"] | to_snake }}(self):
-        input_string = '{{ case["input"]["encoded"] }}'
+        input_string = '{{ case["input"]["encoded"] | escape_invalid_escapes }}'
         {% if case["expected"]["error"] -%}
         with self.assertRaisesWithMessage(ValueError):
             {{ case["property"] | to_snake }}(input_string)
diff --git a/exercises/sgf-parsing/sgf_parsing_test.py b/exercises/sgf-parsing/sgf_parsing_test.py
@@ -70,7 +70,7 @@ def test_multiple_property_values(self):
         self.assertEqual(parse(input_string), expected)
 
     def test_escaped_property(self):
-        input_string = "(;A[\]b\nc\nd\t\te \n\]])"
+        input_string = "(;A[\\]b\nc\nd\t\te \n\\]])"
         expected = SgfTree(properties={"A": ["]b\nc\nd  e \n]"]})
         self.assertEqual(parse(input_string), expected)
 
