Removed unused handles in file-resource-leak (#648)

Author: andrecsilva

src/core_codemods/file_resource_leak.py

@@ -229,12 +229,16 @@ def _handle_block(
                 )
 
                 # grab the index of the last statement with reference to the resource
-                last_index = (
-                    self._find_last_index_with_access(
-                        named_targets, original_block, index
-                    )
-                    or index
+                last_index = self._find_last_index_with_access(
+                    named_targets, original_block, index
                 )
+
+                # No accesses, remove the statement
+                if last_index is None:
+                    new_stmts[index] = cst.Pass()
+                    new_index_of_original_stmt[index] = -1
+                    continue
+
                 # check if the statement in the last_index is now included in some earlier with statement
                 new_last_index = new_index_of_original_stmt[last_index]
 

tests/codemods/test_file_resource_leak.py

@@ -19,6 +19,26 @@ def test_simple(self, tmpdir):
         """
         self.run_and_assert(tmpdir, input_code, expected)
 
+    def test_unused(self, tmpdir):
+        input_code = """
+        file = open('test.txt', 'r')
+        """
+        expected = """
+        """
+        self.run_and_assert(tmpdir, input_code, expected)
+
+    def test_unused_inside_block(self, tmpdir):
+        input_code = """
+        file = open('test.txt', 'r')
+        file2 = open('test2.txt','r')
+        file.read()
+        """
+        expected = """
+        with open('test.txt', 'r') as file:
+            file.read()
+        """
+        self.run_and_assert(tmpdir, input_code, expected, num_changes=2)
+
     def test_simple_annotated(self, tmpdir):
         input_code = """
         file: int = open('test.txt', 'r')
@@ -59,17 +79,6 @@ def foo():
         """
         self.run_and_assert(tmpdir, input_code, expected, num_changes=4)
 
-    def test_just_open(self, tmpdir):
-        # strange as this change may be, it still leaks if left untouched
-        input_code = """
-        file = open('test.txt', 'r')
-        """
-        expected = """
-        with open('test.txt', 'r') as file:
-            pass
-        """
-        self.run_and_assert(tmpdir, input_code, expected)
-
     def test_multiple_assignments(self, tmpdir):
         input_code = """
         file = file2 = open('test.txt', 'r')