Normalise xsd:double text entry answers for Perseus derivation

contentcuration/contentcuration/tests/utils/qti/test_perseus_derive.py

@@ -145,6 +145,22 @@ def test_text_input_derivation():
     assert answers == [{"answer": "42", "correct": True, "order": 0}]
 
 
+@pytest.mark.parametrize(
+    "value,expected",
+    [
+        ("+5", "5"),
+        ("1E3", "1e3"),
+        (" +5 ", "5"),
+        ("+0", "0"),
+    ],
+)
+def test_text_input_normalises_xsd_double_answers(value, expected):
+    result = derive_perseus_item(_Item(_text_item("single", [value])))
+    assert json.loads(result.answers) == [
+        {"answer": expected, "correct": True, "order": 0}
+    ]
+
+
 def test_text_input_multiple_correct_values():
     item = _Item(_text_item("multiple", ["1", "2"]))
     result = derive_perseus_item(item)

contentcuration/contentcuration/tests/utils/test_exercise_creation.py

@@ -2996,3 +2996,20 @@ def test_native_qti_perseus_derivation_resizes_sized_images(self):
             ),
             [(100, 75), (200, 150)],
         )
+
+    def test_native_qti_perseus_derivation_signed_numeric_answer(self):
+        raw_data = _text_item("single", ["+5"])
+        item = self._create_native_qti_item(raw_data)
+
+        self._create_perseus_zip(self._exercise_data([item]))
+
+        exercise_file = self.exercise_node.files.get(preset_id=format_presets.EXERCISE)
+        with storage.open(exercise_file.file_on_disk.name, "rb") as f:
+            zip_file = zipfile.ZipFile(BytesIO(f.read()))
+        qti_id = parse_qti_xml(raw_data.encode("utf-8")).getroot().get("identifier")
+        item_json = json.loads(zip_file.read(f"{qti_id}.json").decode("utf-8"))
+
+        answers = item_json["question"]["widgets"]["numeric-input 1"]["options"][
+            "answers"
+        ]
+        self.assertEqual([answer["value"] for answer in answers], [5])

contentcuration/contentcuration/utils/assessment/qti/perseus_derive.py

@@ -22,6 +22,7 @@
 from contentcuration.utils.assessment.qti.constants import BaseType
 from contentcuration.utils.assessment.qti.html_to_markdown import html_to_markdown
 from contentcuration.utils.assessment.qti.validation import parse_qti_xml
+from contentcuration.utils.parser import extract_value
 
 logger = logging.getLogger(__name__)
 
@@ -194,10 +195,17 @@ def _derive_choice(interaction, item_body, declaration):
     return item_type, question, answers
 
 
+def _perseus_number(value):
+    """A leading "+" and capital "E" are valid xsd:double but not for
+    ``extract_value``."""
+    normalised = value.strip().removeprefix("+").lower()
+    return normalised if extract_value(normalised) is not None else value
+
+
 def _derive_text(interaction, item_body, declaration):
     question = html_to_markdown([item_body])
     answers = [
-        {"answer": value, "correct": True, "order": order}
+        {"answer": _perseus_number(value), "correct": True, "order": order}
         for order, value in enumerate(_accepted_values(declaration))
     ]
     return exercises.INPUT_QUESTION, question, answers