Implement remove method in local storage backend

Implement the new remove method of StorageBackendInterface in the
FilesystemBackend with a simple os.remove() wrapper.

Signed-off-by: Joshua Lock <[email protected]>

Author: joshuagl

securesystemslib/storage.py

@@ -233,6 +233,14 @@ def put(self, fileobj, filepath):
           "Can't write file %s" % filepath)
 
 
+  def remove(self, filepath):
+    try:
+      os.remove(filepath)
+    except (FileNotFoundError, PermissionError, OSError):  # pragma: no cover
+      raise securesystemslib.exceptions.StorageError(
+          "Can't remove file %s" % filepath)
+
+
   def getsize(self, filepath):
     try:
       return os.path.getsize(filepath)

tests/test_storage.py

@@ -81,6 +81,10 @@ def test_files(self):
       with open(put_path, 'rb') as put_file:
         self.assertEqual(put_file.read(), self.fileobj.read())
 
+    self.assertTrue(os.path.exists(put_path))
+    self.storage_backend.remove(put_path)
+    self.assertFalse(os.path.exists(put_path))
+
 
   def test_folders(self):
     leaves = ['test1', 'test2', 'test3']