isoparse: Fail with inconsistent time separators

Fail when separators are used inconsistently to split the time porting
of a string. Even if more restrictive, we have warned that we were going
to fail on invalid cases of ISO formatted strings. This will prevent
invalid iso formatted strings from being unexpectedly parsed.

3 files changed, 12 insertions, 16 deletions

diff --git a/changelog.d/1125.bugfix.rst b/changelog.d/1125.bugfix.rst
new file mode 100644
index 0000000..6ed0449
--- /dev/null
+++ b/changelog.d/1125.bugfix.rst
@@ -0,0 +1 @@
+Make `isoparse` raise when trying to parse times with inconsistent use of `:` separator. Reported and fixed by @mariocj89 (gh pr #1125).
diff --git a/dateutil/parser/isoparser.py b/dateutil/parser/isoparser.py
index 48f86a3..64a54ff 100644
--- a/dateutil/parser/isoparser.py
+++ b/dateutil/parser/isoparser.py
@@ -336,7 +336,7 @@ class isoparser(object):
         if len(timestr) < 2:
             raise ValueError('ISO time too short')
 
-        has_sep = len_str >= 3 and timestr[2:3] == self._TIME_SEP
+        has_sep = False
 
         while pos < len_str and comp < 5:
             comp += 1
@@ -347,13 +347,18 @@ class isoparser(object):
                 pos = len_str
                 break
 
+            if comp == 1 and timestr[pos:pos+1] == self._TIME_SEP:
+                has_sep = True
+                pos += 1
+            elif comp == 2 and has_sep:
+                if timestr[pos:pos+1] != self._TIME_SEP:
+                    raise ValueError('Inconsistent use of colon separator')
+                pos += 1
+
             if comp < 3:
                 # Hour, minute, second
                 components[comp] = int(timestr[pos:pos + 2])
                 pos += 2
-                if (has_sep and pos < len_str and
-                        timestr[pos:pos + 1] == self._TIME_SEP):
-                    pos += 1
 
             if comp == 3:
                 # Fraction of a second
diff --git a/dateutil/test/test_isoparser.py b/dateutil/test/test_isoparser.py
index e81db3a..0c91db7 100644
--- a/dateutil/test/test_isoparser.py
+++ b/dateutil/test/test_isoparser.py
@@ -244,6 +244,8 @@ def test_bytes(isostr, dt):
     ('2012-0425', ValueError),                  # Inconsistent date separators
     ('201204-25', ValueError),                  # Inconsistent date separators
     ('20120425T0120:00', ValueError),           # Inconsistent time separators
+    ('20120425T01:2000', ValueError),           # Inconsistent time separators
+    ('14:3015', ValueError),                    # Inconsistent time separator
     ('20120425T012500-334', ValueError),        # Wrong microsecond separator
     ('2001-1', ValueError),                     # YYYY-M not valid
     ('2012-04-9', ValueError),                  # YYYY-MM-D not valid
@@ -286,17 +288,6 @@ def test_iso_with_sep_raises(sep_act, valid_sep, exception):
         parser.isoparse(isostr)
 
 
-@pytest.mark.xfail() 
-@pytest.mark.parametrize('isostr,exception', [  # pragma: nocover
-    ('20120425T01:2000', ValueError),           # Inconsistent time separators
-])
-def test_iso_raises_failing(isostr, exception):
-    # These are test cases where the current implementation is too lenient
-    # and need to be fixed
-    with pytest.raises(exception):
-        isoparse(isostr)
-
-
 ###
 # Test ISOParser constructor
 @pytest.mark.parametrize('sep', ['  ', '9', '🍛'])
@@ -507,7 +498,6 @@ def test_isotime_raises(isostr, exception):
 
 @pytest.mark.xfail() 
 @pytest.mark.parametrize('isostr,exception', [  # pragma: nocover
-    ('14:3015', ValueError),                    # Inconsistent separator use
     ('201202', ValueError)                      # Invalid ISO format
 ])
 def test_isotime_raises_xfail(isostr, exception):