Handle case where import files are empty

home/import_assessments.py

@@ -106,20 +106,24 @@ def parse_file(self) -> list["AssessmentRow"]:
             c. Validates that the snake_case headers contain all mandatory headers.
             d. Transforms each row to use snake_case headers.
         """
+
         row_iterator = parse_file(self.file_content, self.file_type)
         rows = [row for _, row in row_iterator]
 
-        if rows:
-            original_headers = rows[0].keys()
-            headers_mapping = {
-                header: self.to_snake_case(header) for header in original_headers
-            }
-            snake_case_headers = list(headers_mapping.values())
-            self.validate_headers(snake_case_headers, MANDATORY_HEADERS, row_num=1)
-            transformed_rows = [
-                {headers_mapping[key]: value for key, value in row.items()}
-                for row in rows
-            ]
+        if not rows:
+            raise ImportAssessmentException(
+                "The import file is empty or contains no valid rows.", row_num=1
+            )
+
+        original_headers = rows[0].keys()
+        headers_mapping = {
+            header: self.to_snake_case(header) for header in original_headers
+        }
+        snake_case_headers = list(headers_mapping.values())
+        self.validate_headers(snake_case_headers, MANDATORY_HEADERS, row_num=1)
+        transformed_rows = [
+            {headers_mapping[key]: value for key, value in row.items()} for row in rows
+        ]
 
         return [
             AssessmentRow.from_flat(row, i + 2)

home/import_helpers.py

@@ -169,7 +169,11 @@ def fix_rows(rows: Iterator[dict[str | Any, Any]]) -> Iterator[dict[str, str | N
     """
     Fix keys for all rows by lowercasing keys and removing whitespace from keys and values
     """
-    first_row = next(rows)
+    try:
+        first_row = next(rows)
+    except StopIteration:
+        return iter([])
+
     if len(first_row) != len(fix_row(first_row)):
         raise ImportException(
             "Invalid format. Please check that there are no duplicate headers."

home/tests/import-export-data/empty.csv

@@ -0,0 +1 @@
+

home/tests/test_assessment_import_export.py

@@ -427,7 +427,7 @@ def test_single_assessment(self, impexp: ImportExport) -> None:
 
     def test_snake_case_assessments(self, csv_impexp: ImportExport) -> None:
         """
-        Importing a csv with spaces in header names and uppercase text should be coverted to snake case
+        Importing a csv with spaces in header names and uppercase text should be converted to snake case
         and pass, provided that the converted text are valid cms headers.
         Here we check that the headers are changed to snake case, the assessment is saved
         and finally we check that the saved assessment has the correct headers.
@@ -440,25 +440,24 @@ def test_snake_case_assessments(self, csv_impexp: ImportExport) -> None:
         assessment_model = Assessment
         model_fields = [field.name for field in assessment_model._meta.get_fields()]
 
-        expected_fields = {
-            "title": True,
-            "slug": True,
-            "high_inflection": True,
-            "medium_inflection": True,
-            "high_result_page": True,
-            "medium_result_page": True,
-            "low_result_page": True,
-            "skip_high_result_page": True,
-            "skip_threshold": True,
-            "generic_error": True,
-            "questions": True,
-        }
-
-        for field_name, should_exist in expected_fields.items():
-            if should_exist:
-                assert (
-                    field_name in model_fields
-                ), f"Field '{field_name}' not found in Assessment model."
+        expected_fields = [
+            "title",
+            "slug",
+            "high_inflection",
+            "medium_inflection",
+            "high_result_page",
+            "medium_result_page",
+            "low_result_page",
+            "skip_high_result_page",
+            "skip_threshold",
+            "generic_error",
+            "questions",
+        ]
+
+        for field_name in expected_fields:
+            assert (
+                field_name in model_fields
+            ), f"Field '{field_name}' not found in Assessment model."
 
 
 @pytest.mark.usefixtures("result_content_pages")
@@ -702,6 +701,16 @@ def test_missing_generic_error(self, csv_impexp: ImportExport) -> None:
         )
         assert e.value.row_num == 2
 
+    def test_empty_rows(self, csv_impexp: ImportExport) -> None:
+        """
+        Importing an empty CSV should return an error that the
+        import file has no rows.
+        """
+        with pytest.raises(ImportAssessmentException) as e:
+            csv_impexp.import_file("empty.csv")
+        assert e.value.message == "The import file is empty or contains no valid rows."
+        assert e.value.row_num == 1
+
 
 @pytest.mark.usefixtures("result_content_pages")
 @pytest.mark.django_db()