Enforce unique items

src/stateful_data_processor/processor.py

@@ -51,11 +51,11 @@ def __init__(
         signal.signal(signal.SIGTERM, self._signal_handler)
 
     @abstractmethod
-    def process_data(self, *args, **kwargs):
+    def process_data(self, items, *args, **kwargs):
         """Template method for processing data. Get data, and call _iterate_items.
         Arguments are forwarded to _iterate_items. You can override this method to implement
         more custom processing."""
-        self._iterate_items(*args, **kwargs)
+        self._iterate_items(items, *args, **kwargs)
 
     def _iterate_items(self, items, *args, **kwargs):
         """General iteration method for processing items. This should be called from process_data.
@@ -89,10 +89,18 @@ def _signal_handler(self, signum, frame):
         self.logger.info("Data saved, exiting.")
         exit(0)
 
-    def run(self, *args, **kwargs):
+    def run(self, items, *args, **kwargs):
         """Main method to run the processor."""
+        if not items:
+            self.logger.error("No items to process.")
+            return
+
+        if sorted(list(set(items))) != list(items):
+            self.logger.error("Items must be unique.")
+            return
+
         try:
-            self.process_data(*args, **kwargs)
+            self.process_data(items, *args, **kwargs)
         except Exception as e:
             raise e
         self.file_rw.write(self.data)

tests/test_processor.py

@@ -55,6 +55,14 @@ def tearDown(self) -> None:
             os.remove(TEST_FILE_JSON_PATH)
         del self.file_rw
 
+    def test_items_must_be_unique(self):
+        processor = SymbolProcessor(self.file_rw, should_read=False, logger=self.mock_logger)
+        processor.run(items=["a", "a", "b"], delay=0)
+        calls = [
+            call("Items must be unique."),
+        ]
+        self.mock_logger.error.assert_has_calls(calls, any_order=True)
+
     def test_process_data(self):
         processor = SymbolProcessor(
             self.file_rw, should_read=False, logger=self.mock_logger