Fix IndexError for a from-import at end of file without trailing newline

CHANGELOG.md

@@ -4,6 +4,7 @@
 - #896 patchedast cleanup and refactoring (@lieryan)
 - #905 Ignore `node_modules` directories by default when scanning project files and source folders. (@marcoeangeli)
 - #933 Add type annotations to project.py (@lieryan)
+- #119 Fix IndexError in rename and find occurrences when a `from` import is the last thing in a module without a trailing newline (@mcepl)
 
 # Release 1.15.1
 

rope/base/worder.py

@@ -425,6 +425,8 @@ def is_from_aliased(self, offset):
             return False
         try:
             end = self._find_word_end(offset)
+            if not self._has_enough_len_for_as(end):
+                return False
             as_end = min(self._find_word_end(end + 1), len(self.code))
             as_start = self._find_word_start(as_end)
             return self.code[as_start : as_end + 1] == "as"

ropetest/codeanalyzetest.py

@@ -507,6 +507,16 @@ def test_is_from_aliased(self):
             self._make_offset_annotation(code, word_finder.is_from_aliased),
         )
 
+    def test_is_from_aliased_at_end_of_file_without_newline(self):
+        code = "from os import system"
+        word_finder = worder.Worder(code)
+        self.assertFalse(word_finder.is_from_aliased(code.index("system")))
+
+    def test_is_import_statement_aliased_module_at_end_of_file_without_newline(self):
+        code = "import os"
+        word_finder = worder.Worder(code)
+        self.assertFalse(word_finder.is_import_statement_aliased_module(code.index("os")))
+
     def test_is_from_with_from_import_and_multiline_parens(self):
         code = "from mod import \\\n  (f,\n  g, h)\n"
         word_finder = worder.Worder(code)

ropetest/refactor/renametest.py

@@ -524,6 +524,18 @@ def new_func():
             mod2.read(),
         )
 
+    def test_renaming_from_import_at_end_of_file_without_newline(self):
+        mod1 = testutils.create_module(self.project, "mod1")
+        mod1.write("def a_func():\n    pass\n")
+        mod2 = testutils.create_module(self.project, "mod2")
+        mod2.write("from mod1 import a_func")
+        mod3 = testutils.create_module(self.project, "mod3")
+        mod3.write("from mod2 import a_func\na_func()\n")
+        self._rename(mod3, mod3.read().rindex("a_func"), "new_func")
+        self.assertEqual("def new_func():\n    pass\n", mod1.read())
+        self.assertEqual("from mod1 import new_func", mod2.read())
+        self.assertEqual("from mod2 import new_func\nnew_func()\n", mod3.read())
+
     def test_renaming_functions_across_modules_from_import(self):
         mod1 = testutils.create_module(self.project, "mod1")
         mod1.write(dedent("""\