Merge pull request #140 from fsouza/fix-IndexError-empty-file

Avoid IndexError when extracting typing statements

src/autoimport/model.py

@@ -151,7 +151,7 @@ def _extract_typing_statements(self, source_lines: List[str]) -> None:
         """
         typing_start_line = len(self.header) + len(self.imports)
 
-        if len(source_lines) > 0 and re.match(
+        if typing_start_line < len(source_lines) and re.match(
             r"^if TYPE_CHECKING:$", source_lines[typing_start_line]
         ):
             self.typing.append(source_lines[typing_start_line])

tests/unit/test_services.py

@@ -840,3 +840,21 @@ def test_fix_doesnt_fail_on_empty_file() -> None:
     result = fix_code(source)
 
     assert result == source
+
+
+def test_file_that_only_has_unused_imports() -> None:
+    """
+    Given: A file that only has unused imports.
+    When: Fix code is run.
+    Then: The output should be a single empty line.
+    """
+    source = dedent(
+        """\
+        import os
+        import sys
+        """
+    )
+
+    result = fix_code(source)
+
+    assert result == "\n"