From 569cb99ca75621e4407fd0cf4f708388065c526d Mon Sep 17 00:00:00 2001
From: Dave Halter <davidhalter88@gmail.com>
Date: Wed, 19 Jul 2017 18:45:58 +0200
Subject: [PATCH] Start scanning for indentation errors.

---
 parso/python/normalizer.py         | 13 ++++++++++++-
 parso/python/tree.py               | 13 +++++++++++++
 test/normalizer_issue_files/E11.py |  2 +-
 test/test_python_errors.py         | 17 +++++++++++++----
 4 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/parso/python/normalizer.py b/parso/python/normalizer.py
index bac0ce7..0a0d7cc 100644
--- a/parso/python/normalizer.py
+++ b/parso/python/normalizer.py
@@ -67,10 +67,21 @@ class ErrorFinder(Normalizer):
 
     def visit_leaf(self, leaf):
         if leaf.type == 'error_leaf':
-            self._add_syntax_error("Syntax Error", leaf)
+            if leaf.original_type == 'indent':
+                # Indents/Dedents itself never have a prefix. They are just
+                # "pseudo" tokens that get removed by the syntax tree later.
+                # Therefore in case of an error we also have to check for this.
+                spacing = list(leaf.get_next_leaf()._split_prefix())[-1]
+                self._add_indentation_error("Indentation Error", spacing)
+                print(leaf, repr(leaf.prefix), repr(leaf.value), leaf.get_previous_leaf())
+            else:
+                self._add_syntax_error("Syntax Error", leaf)
 
         return ''
 
+    def _add_indentation_error(self, message, spacing):
+        self._add_error(903, message, spacing)
+
     def _add_syntax_error(self, message, node):
         self._add_error(901, message, node)
 
diff --git a/parso/python/tree.py b/parso/python/tree.py
index 7afddb0..0f541b4 100644
--- a/parso/python/tree.py
+++ b/parso/python/tree.py
@@ -103,6 +103,19 @@ class PythonLeaf(PythonMixin, Leaf):
     def _split_prefix(self):
         return split_prefix(self, self.get_start_pos_of_prefix())
 
+    def get_start_pos_of_prefix(self):
+        # TODO it is really ugly that we have to override it. Maybe change
+        #   indent error leafs somehow? No idea how, though.
+        previous_leaf = self.get_previous_leaf()
+        if previous_leaf is not None and previous_leaf.type == 'error_leaf' \
+                and previous_leaf.original_type == 'indent':
+            previous_leaf = previous_leaf.get_previous_leaf()
+
+        if previous_leaf is None:
+            return self.line - self.prefix.count('\n'), 0  # It's the first leaf.
+        return previous_leaf.end_pos
+
+
 
 class _LeafWithoutNewlines(PythonLeaf):
     """
diff --git a/test/normalizer_issue_files/E11.py b/test/normalizer_issue_files/E11.py
index 9e82c86..9b97f39 100644
--- a/test/normalizer_issue_files/E11.py
+++ b/test/normalizer_issue_files/E11.py
@@ -15,7 +15,7 @@ if False:
     pass
 print
 print
-#: E901:4
+#: E903:0
     print
 mimetype = 'application/x-directory'
 #: E111:5
diff --git a/test/test_python_errors.py b/test/test_python_errors.py
index 660e10d..803bce9 100644
--- a/test/test_python_errors.py
+++ b/test/test_python_errors.py
@@ -14,6 +14,11 @@ def _get_error_list(code, version=None):
     return list(tree._get_normalizer_issues(config))
 
 
+def assert_comparison(code, error_code, positions):
+    errors = [(error.start_pos, error.code) for error in _get_error_list(code)]
+    assert [(pos, error_code) for pos in positions] == errors
+
+
 @pytest.mark.parametrize(
     ('code', 'positions'), [
         ('1 +', [(1, 3)]),
@@ -34,9 +39,13 @@ def _get_error_list(code, version=None):
     ]
 )
 def test_syntax_errors(code, positions):
-    errors = [(error.start_pos, error.code) for error in _get_error_list(code)]
-    assert [(pos, 901) for pos in positions] == errors
+    assert_comparison(code, 901, positions)
 
 
-def test_indentation_errors():
-    pass
+@pytest.mark.parametrize(
+    ('code', 'positions'), [
+        (' 1', [(1, 0)]),
+    ]
+)
+def test_indentation_errors(code, positions):
+    assert_comparison(code, 903, positions)