Don't save unmodified file to the disk

CHANGES.md

@@ -41,6 +41,9 @@
   robotidy --check --overwrite src
   ```
 
+### Fixes
+- Unmodified files are now not saved to the disk ([#237](https://github.com/MarketSquare/robotframework-tidy/issues/237))
+
 ## 1.6.2
 
 ### Fixes

robotidy/app.py

@@ -67,7 +67,7 @@ def transform_files(self):
                 self.output_diff(model.source, old_model, new_model)
                 if stdin:
                     self.print_to_stdout(new_model)
-                else:
+                elif diff:
                     self.save_model(model.source, model)
             except DataError:
                 click.echo(

tests/atest/transformers/AlignTestCases/test_transformer.py

@@ -11,21 +11,23 @@ class TestAlignTestCases(TransformerAcceptanceTest):
         [
             "test.robot",
             "no_header_col.robot",
-            "for_loops.robot",
             "with_settings.robot",
             "templated_for_loops.robot",
             "templated_for_loops_and_without.robot",
             "templated_for_loops_header_cols.robot",
-            "empty_line.robot",
         ],
     )
     def test_transformer(self, source):
         self.compare(source=source, expected=source)
 
+    @pytest.mark.parametrize("source", ["for_loops.robot", "empty_line.robot"])
+    def test_should_not_modify(self, source):
+        self.compare(source=source, not_modified=True)
+
     def test_only_with_headers(self):
         self.compare(
             source="no_header_col.robot",
-            expected="no_header_col_only_headers.robot",
+            not_modified=True,
             config=":only_with_headers=True",
         )