Public API for creating and loading answer from student name

The existing functions did not allow to specify the student name without
changing the value of the dropdown menu. With the new function structure
we can now create and load new files from the student name.

One can create and load now with Python API the ExerciseWidget

```python
exercise_widget.create_new_file_from_student_name(name)
exercise_widget.load_file_from_student_name(name)
```

src/scwidgets/exercise/_widget_exercise_registry.py

@@ -70,14 +70,14 @@ def answer(self, answer: dict):
     def handle_save_result(self, result: Union[str, Exception]) -> None:
         """
         Function that controls how a save result is handled. If the result is a string,
-        the saving was succesfull. The result contains a string that can be outputed.
+        the saving was successfull. The result contains a string that can be outputed.
         """
         raise NotImplementedError("handle_save_result has not been implemented")
 
     def handle_load_result(self, result: Union[str, Exception]) -> None:
         """
         Function that controls how a load result is handled. If the result is a string,
-        the loading was succesfull. The result contains a string that can be outputed.
+        the loading was successfull. The result contains a string that can be outputed.
         """
         raise NotImplementedError("handle_load_result has not been implemented")
 
@@ -271,7 +271,7 @@ def registered_widgets(self):
         return self._widgets.copy()
 
     @property
-    def loaded_file_name(self):
+    def loaded_file_name(self) -> Union[str, None]:
         return self._loaded_file_name
 
     def register_widget(self, widget: ExerciseWidget, exercise_key: Hashable):
@@ -284,24 +284,46 @@ def register_widget(self, widget: ExerciseWidget, exercise_key: Hashable):
         """
         self._widgets[exercise_key] = widget
 
-    def create_new_file(self) -> str:
-        FilenameParser.verify_valid_student_name(self._student_name_text.value)
+    def create_new_file_from_dropdown(self) -> str:
+        """Creates a new file containing all students answers from the selected
+        file in the dropdown menu.
+
+        :raises FileExistsError: If the file arleady exists
+        :return: A message to print
+        """
+        self.create_new_file_from_student_name(self._student_name_text.value)
+        return f"File {self._loaded_file_name!r} created and loaded."
+
+    def get_answer_filename(self, student_name: str) -> str:
+        """Returns the filename containing all answers for the student name.
+
+        :param student_name: The name of the student used for the filename
+        :raises ValueError: If student name is not valid
+        :return: The filename
+        """
+        FilenameParser.verify_valid_student_name(student_name)
 
         answers_filename = ""
         # if prefix is defined, it is added to the filename
         if self._filename_prefix is not None:
             answers_filename += self._filename_prefix + "-"
-        student_name_standardized = FilenameParser.standardize_filename(
-            self._student_name_text.value
-        )
+        student_name_standardized = FilenameParser.standardize_filename(student_name)
         answers_filename += student_name_standardized + ".json"
+        return answers_filename
+
+    def create_new_file_from_student_name(self, student_name: str):
+        """Creates a new exercise file containing all students answers.
+
+        :param student_name: The name of the student used for the exercise file
+        :raises FileExistsError: If the file arleady exists
+        :return: A message to print
+        """
+        answers_filename = self.get_answer_filename(student_name)
 
         if os.path.exists(answers_filename):
-            raise ValueError(
-                "The name "
-                f"{student_name_standardized!r} "
-                f"is already used in file {answers_filename!r}. Please provide a "
-                "new name."
+            raise FileExistsError(
+                f"The name is already used for file {answers_filename!r}."
+                " Please provide a new name."
             )
         else:
             answers = {key: widget.answer for key, widget in self._widgets.items()}
@@ -318,7 +340,6 @@ def create_new_file(self) -> str:
             self._show_lower_panel_box()
 
             self._loaded_file_name = answers_filename
-            return f"File {answers_filename!r} created and loaded."
 
     def load_answer(self, exercise_key: Hashable) -> str:
         """
@@ -356,29 +377,41 @@ def load_answer(self, exercise_key: Hashable) -> str:
         self._loaded_file_name = answers_filename
         return f"Exercise has been loaded from file {answers_filename!r}."
 
-    def load_file(self) -> str:
+        self._answers_files_dropdown.value
+
+    def load_file_from_dropdown(self) -> str:
         """
-        Loads all answers from selected file in the dropdown menu
+        Loads all answers from the selected file in the dropdown menu.
         """
         if (
             self._answers_files_dropdown.value
             == self._create_new_file_dropdown_option()
         ):
             raise ValueError("No file has been selected in the dropdown list.")
         if self._loaded_file_name is None:
-            if (
-                self._answers_files_dropdown.value
-                == self._create_new_file_dropdown_option()
-            ):
-                raise ValueError("No file has been selected in the dropdown list.")
             answers_filename = self._answers_files_dropdown.value
         else:
             answers_filename = self._loaded_file_name
 
+        self.load_file(answers_filename)
+        return f"All answers loaded from file {self._loaded_file_name!r}."
+
+    def load_file_from_student_name(self, student_name: str):
+        self.load_file(self.get_answer_filename(student_name))
+
+    def load_file(self, answers_filename: str):
+        """
+        Loads all answers from the selected file in the dropdown menu.
+
+        :raises FileNotFoundError: If the file cannot be found
+        :raises ValueError: If the loaded file contains an answer with key that
+            has not been registered
+        """
+
         if not (os.path.exists(answers_filename)):
             raise FileNotFoundError(
                 "Selected file does not exist anymore. Maybe you have renamed "
-                "or deleted it?Please choose another file or create a new one."
+                "or deleted it? Please choose another file or create a new one."
             )
 
         with open(answers_filename, "r") as answers_file:
@@ -393,11 +426,15 @@ def load_file(self) -> str:
                 self._widgets[exercise_key].answer = answer
         self._loaded_file_name = answers_filename
 
-        # only notifiy all widgets when result was successful
+        # only notify all widgets when result was successful
         for widget in self._widgets.values():
             result = f"Exercise has been loaded from file {self._loaded_file_name!r}."
             widget.handle_load_result(result)
-        return f"All answers loaded from file {answers_filename!r}."
+
+        self._answers_files_dropdown.value = answers_filename
+        self._disable_upper_panel_box()
+        self._enable_lower_panel_box()
+        self._show_lower_panel_box()
 
     def save_answer(self, exercise_key: Hashable) -> str:
         if not (exercise_key in self._widgets.keys()):
@@ -482,10 +519,7 @@ def _on_click_load_file_button(self, change: dict):
         self._output.clear_output(wait=True)
         with self._output:
             try:
-                result = self.load_file()
-                self._disable_upper_panel_box()
-                self._enable_lower_panel_box()
-                self._show_lower_panel_box()
+                result = self.load_file_from_dropdown()
                 print(Formatter.color_success_message(result))
             except Exception as exception:
                 print(Formatter.color_error_message("Error raised while loading file:"))
@@ -510,7 +544,7 @@ def _on_click_confirm_create_new_file_button(self, change: dict):
         self._output.clear_output(wait=True)
         with self._output:
             try:
-                result = self.create_new_file()
+                result = self.create_new_file_from_dropdown()
                 print(Formatter.color_success_message(result))
             except Exception as exception:
                 print(

tests/test_answer.py

@@ -67,7 +67,7 @@ def teardown_method(self, method):
         for filename in glob.glob(os.getcwd() + f"/{self.prefix}-*.json"):
             os.remove(filename)
 
-    def test_create_new_file(self):
+    def test_create_new_file_from_dropdown(self):
         answers = {"exercise_1": "update", "exercise_2": "answer_2"}
         with open(f"{self.prefix}-{self.student_name}-2.json", "w") as answer_file:
             json.dump(answers, answer_file)
@@ -86,18 +86,18 @@ def test_create_new_file(self):
         # simulating typing of name into text widget
         answer_registry._student_name_text.value = self.student_name
         assert not (os.path.exists(f"{self.prefix}-{self.student_name}.json"))
-        answer_registry.create_new_file()
+        answer_registry.create_new_file_from_dropdown()
 
         with open(f"{self.prefix}-{self.student_name}.json", "r") as answer_file:
             answers = json.load(answer_file)
         assert answers == {"exercise_1": "answer_1"}
 
         with pytest.raises(
-            ValueError,
-            match=r".*The name 'test-answer-registry' "
-            "is already used in file 'pytest-test-answer-registry.json'.*",
+            FileExistsError,
+            match=r".*The name is already used for file "
+            "'pytest-test-answer-registry.json'.*",
         ):
-            answer_registry.create_new_file()
+            answer_registry.create_new_file_from_dropdown()
 
     def test_save_answer(self):
         answer_registry = ExerciseRegistry(filename_prefix=self.prefix)
@@ -118,7 +118,7 @@ def test_save_answer(self):
 
         # create file
         answer_registry._student_name_text.value = self.student_name
-        answer_registry.create_new_file()
+        answer_registry.create_new_file_from_dropdown()
 
         # Tests if error is raised on moved file
         os.rename(f"{self.prefix}-{self.student_name}.json", "tmp.json")
@@ -157,7 +157,7 @@ def test_save_all_answers(self):
 
         # create file
         answer_registry._student_name_text.value = self.student_name
-        answer_registry.create_new_file()
+        answer_registry.create_new_file_from_dropdown()
 
         # Tests if error is raised on moved file
         os.rename(f"{self.prefix}-{self.student_name}.json", "tmp.json")
@@ -182,7 +182,7 @@ def test_save_all_answers(self):
             answers = json.load(answer_file)
         assert answers == {"exercise_1": "update", "exercise_2": "answer_2"}
 
-    def test_load_file(self):
+    def test_load_file_from_dropdown(self):
         answers = {"exercise_1": "update_1", "exercise_2": "update_2"}
         with open(f"{self.prefix}-{self.student_name}.json", "w") as answer_file:
             json.dump(answers, answer_file)
@@ -204,7 +204,7 @@ def test_load_file(self):
         with pytest.raises(
             ValueError, match=r".*No file has been selected in the dropdown list.*"
         ):
-            answer_registry.load_file()
+            answer_registry.load_file_from_dropdown()
         # select back file to load
         answer_registry._answers_files_dropdown.value = (
             f"{self.prefix}-{self.student_name}.json"
@@ -215,7 +215,7 @@ def test_load_file(self):
         with pytest.raises(
             FileNotFoundError, match=r".*Selected file does not exist anymore.*"
         ):
-            answer_registry.load_file()
+            answer_registry.load_file_from_dropdown()
         os.rename("tmp.json", f"{self.prefix}-{self.student_name}.json")
 
         # Test that file is contains only the updated answer
@@ -224,12 +224,12 @@ def test_load_file(self):
             match=r".*Your file contains an answer with key 'exercise_2' "
             r"with no corresponding registered widget.*",
         ):
-            answer_registry.load_file()
+            answer_registry.load_file_from_dropdown()
 
         exercise_key_2 = "exercise_2"
         answer_widget_2 = mock_answer_widget(answer_registry, exercise_key_2)
         answer_widget_2.answer = "answer_2"
-        result = answer_registry.load_file()
+        result = answer_registry.load_file_from_dropdown()
         assert (
             result == "All answers loaded from file 'pytest-test-answer-registry.json'."
         )
@@ -267,7 +267,7 @@ def test_load_answer(self):
         answer_registry._answers_files_dropdown.value = (
             f"{self.prefix}-{self.student_name}.json"
         )
-        answer_registry.load_file()
+        answer_registry.load_file_from_dropdown()
 
         # Tests if error is raised on moved file
         os.rename(f"{self.prefix}-{self.student_name}.json", "tmp.json")

tests/test_code.py

@@ -344,7 +344,7 @@ def print_success(code_ex: CodeExercise | None):
         )
 
         exercise_registry._student_name_text.value = "test_save_registry-student_name"
-        exercise_registry.create_new_file()
+        exercise_registry.create_new_file_from_dropdown()
         code_ex._save_button.click()
         os.remove("test_save_registry-student_name.json")