Simplify change validation

soundchanger/change.py

@@ -1,7 +1,7 @@
 import re
 
 
-def apply(changes, strings, categories={}, apply=True, zero_characters=['∅']):
+def apply(changes, strings, categories={}, ignore_errors=True, apply=True, zero_characters=['∅']):
     """Apply a sound change to a given string"""
 
     if not apply:
@@ -15,7 +15,9 @@ def apply(changes, strings, categories={}, apply=True, zero_characters=['∅']):
         strings = [strings]
 
     for change in changes:
-        validate_change(change)
+        v = validate_change(change, ignore_errors=ignore_errors)
+        if v == False:
+            continue
         change = convert_change_to_regex(change, categories=categories, zero_characters=zero_characters)
 
         original, change_to, before, after = split_change(change)
@@ -32,11 +34,13 @@ def apply(changes, strings, categories={}, apply=True, zero_characters=['∅']):
     return strings
 
 
-def validate_change(change):
-    if change.count('>') != 1:
-        raise ValueError(f"Change {change} is not a valid sound change. (Missing character '>')")
-    if change.count('/') > 1:
-        raise ValueError(f"Change {change} is not a valid sound change. (More than one '/' character)")
+def validate_change(change, ignore_errors):
+    valid = re.search(r'^[^>_/]+?>[^>_/]*?(:?/[^>_/]*?_+[^>_/]*)?$', change)
+    if ignore_errors:
+        return valid != None
+    if not valid:
+        raise ValueError(f"Change {change} is not a valid sound change.")
+    return True
 
 
 def convert_change_to_regex(change, categories, zero_characters):
@@ -65,15 +69,9 @@ def split_change(change):
         environment = '_'
 
     # Collaplse multiple underscores
-    environment = re.sub('(_+)', '_', environment)
-
-    if environment.count('_') != 1:
-        raise ValueError(f"Environment {environment} is not a valid environment. (Character '_' should exist exactly once)")
+    environment = re.sub('_+', '_', environment)
 
     original, change_to = change.split('>')
     before, after = environment.split('_')
 
-    if not original:
-        raise ValueError(f"Nothing to change from.")
-    
     return (original, change_to, before, after)

tests/test_change.py

@@ -88,3 +88,7 @@ def test_multiple_strings():
 
 def test_multiple_changes_and_strings():
     assert apply(['p>f', 'f>h/#_a'], ['pana', 'pune']) == ['hana', 'fune']
+
+def test_applying_invalid_change():
+    assert apply('', 'pana') == 'pana'
+    assert apply(['p>f', '>', 'f>h'], 'pana') == 'hana'

tests/test_change_errors.py

@@ -3,17 +3,21 @@ import re
 from soundchanger.change import apply
 
 def test_error_in_change():
-    with pytest.raises(ValueError, match=re.escape("Change  is not a valid sound change. (Missing character '>')")):
-        apply('', '')
+    # with pytest.raises(ValueError, match=re.escape("Change  is not a valid sound change. (Missing character '>')")):
+    with pytest.raises(ValueError, match=re.escape("Change  is not a valid sound change.")):
+        apply('', '', ignore_errors=False)
 
 def test_error_split():
-    with pytest.raises(ValueError, match=re.escape("Change a>b/c/d is not a valid sound change. (More than one '/' character)")):
-        apply('a>b/c/d', '')
+    # with pytest.raises(ValueError, match=re.escape("Change a>b/c/d is not a valid sound change. (More than one '/' character)")):
+    with pytest.raises(ValueError, match=re.escape("Change a>b/c/d is not a valid sound change.")):
+        apply('a>b/c/d', '', ignore_errors=False)
 
 def test_error_in_environment():
-    with pytest.raises(ValueError, match=re.escape("Environment c is not a valid environment. (Character '_' should exist exactly once)")):
-        apply('a>b/c', '')
+    # with pytest.raises(ValueError, match=re.escape("Environment c is not a valid environment. (Character '_' should exist exactly once)")):
+    with pytest.raises(ValueError, match=re.escape("Change a>b/c is not a valid sound change.")):
+        apply('a>b/c', '', ignore_errors=False)
 
 def test_no_change_from():
-    with pytest.raises(ValueError, match=re.escape("Nothing to change from.")):
-        apply('>b', '')
+    # with pytest.raises(ValueError, match=re.escape("Nothing to change from.")):
+    with pytest.raises(ValueError, match=re.escape("Change >b is not a valid sound change.")):
+        apply('>b', '', ignore_errors=False)