Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

backend/app/tests/assessment/test_dataset.py (3)

148-163: 💤 Low value

Consider importing openpyxl at module level.

openpyxl is already imported at line 7 for InvalidFileException. Importing it again inside the test function (lines 149, 151) is inconsistent with the module-level import pattern.

♻️ Proposed consolidation

At the top of the file, consolidate the imports:

 from openpyxl.utils.exceptions import InvalidFileException
+import openpyxl
+import io

Then remove the inline imports in the test functions.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@backend/app/tests/assessment/test_dataset.py` around lines 148 - 163, The
test function test_preview_excel_returns_headers_and_rows imports openpyxl
locally even though openpyxl is already imported at module level for
InvalidFileException; remove the inline imports inside
test_preview_excel_returns_headers_and_rows and any other tests, and add/ensure
a single module-level import for openpyxl alongside InvalidFileException so the
test uses that top-level import instead.

---

142-146: ⚡ Quick win

Strengthen the latin-1 fallback assertion.

The test claims to verify latin-1 fallback but only checks that the value starts with "ca". It should verify that the invalid UTF-8 byte \xff was correctly decoded as ÿ (U+00FF in latin-1) rather than dropped.

✨ Proposed stronger assertion

     def test_preview_csv_handles_latin1_fallback(self) -> None:
         # \xff is invalid utf-8 -> falls back to latin-1
         headers, rows = _preview_csv(b"name\nca\xfffe\n", limit=5)
         assert headers == ["name"]
-        assert rows and rows[0][0].startswith("ca")
+        assert rows and rows[0][0] == "caÿfe"

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@backend/app/tests/assessment/test_dataset.py` around lines 142 - 146, Update
the test_preview_csv_handles_latin1_fallback assertion to verify the latin-1
decoded character is present: call _preview_csv as before, then assert that the
first cell exactly equals "caÿ" or contains the Unicode character U+00FF (ÿ) to
ensure the invalid UTF-8 byte 0xFF was decoded via latin-1; refer to the test
function name test_preview_csv_handles_latin1_fallback and the helper
_preview_csv when locating the change.

---

165-175: ⚡ Quick win

Clarify expected behavior for empty workbooks.

The assertion at line 174 accepts two different outcomes ([""] or []), which suggests either:

1. The expected behavior for empty workbooks is not well-defined, or
2. The test is being overly permissive.

Consider determining the correct expected behavior and asserting only that outcome.

♻️ Proposed fix

If empty workbooks should return an empty list:

-        assert headers == [""] or headers == []
+        assert headers == []

Or if they should return a list with one empty string:

-        assert headers == [""] or headers == []
+        assert headers == [""]

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@backend/app/tests/assessment/test_dataset.py` around lines 165 - 175, The
test test_preview_excel_empty_workbook is ambiguous because it accepts two
outcomes for headers; decide the canonical behavior for _preview_excel (either
return [] for no headers or [""] to represent a single empty header) and update
the test to assert that single expected value only; locate the test function
test_preview_excel_empty_workbook and the helper _preview_excel, then change the
assertion to assert headers == <chosen_expected_value> (and keep assert rows ==
[]), or if you choose to change _preview_excel instead, make it return the
chosen headers shape for an empty workbook and keep the test asserting that one
outcome.