fix: suppress traceback in shell if no ipython installed

Old implementation was showing import error, new implementation instead
hides it behind separated call and if-else check

src/ahriman/application/interactive_shell.py

@@ -18,6 +18,7 @@
 # along with this program. If not, see <http://www.gnu.org/licenses/>.
 #
 from code import InteractiveConsole
+from importlib.util import find_spec
 from typing import Any
 
 
@@ -26,6 +27,19 @@ class InteractiveShell(InteractiveConsole):
     wrapper around :class:`code.InteractiveConsole` to pass :func:`interact()` to IPython shell
     """
 
+    @staticmethod
+    def has_ipython() -> bool:
+        """
+        check if IPython shell is available
+
+        Returns:
+            bool: ``True`` if IPython shell is available, ``False`` otherwise
+        """
+        try:
+            return find_spec("IPython.terminal.embed") is not None
+        except ModuleNotFoundError:
+            return False
+
     def interact(self, *args: Any, **kwargs: Any) -> None:
         """
         pass controller to IPython shell
@@ -34,13 +48,13 @@ class InteractiveShell(InteractiveConsole):
             *args(Any): positional arguments
             **kwargs(Any): keyword arguments
         """
-        try:
+        if self.has_ipython():
             from IPython.terminal.embed import InteractiveShellEmbed
 
             shell = InteractiveShellEmbed(user_ns=self.locals)  # type: ignore[no-untyped-call]
             shell.show_banner()  # type: ignore[no-untyped-call]
             shell.interact()  # type: ignore[no-untyped-call]
-        except ImportError:
+        else:
             # fallback to default
             import readline  # pylint: disable=unused-import
             InteractiveConsole.interact(self, *args, **kwargs)

tests/ahriman/application/test_interactive_shell.py

@@ -1,14 +1,30 @@
-import pytest
-
 from pytest_mock import MockerFixture
 
 from ahriman.application.interactive_shell import InteractiveShell
 
 
+def test_has_ipython(mocker: MockerFixture) -> None:
+    """
+    must correctly check if IPython is installed
+    """
+    find_spec_mock = mocker.patch("ahriman.application.interactive_shell.find_spec")
+    assert InteractiveShell.has_ipython()
+    find_spec_mock.assert_called_once_with("IPython.terminal.embed")
+
+
+def test_has_ipython_module_not_found(mocker: MockerFixture) -> None:
+    """
+    must return False if IPython is not installed
+    """
+    mocker.patch("ahriman.application.interactive_shell.find_spec", side_effect=ModuleNotFoundError)
+    assert not InteractiveShell.has_ipython()
+
+
 def test_interact(mocker: MockerFixture) -> None:
     """
     must call IPython shell
     """
+    mocker.patch("ahriman.application.interactive_shell.InteractiveShell.has_ipython", return_value=True)
     banner_mock = mocker.patch("IPython.terminal.embed.InteractiveShellEmbed.show_banner")
     interact_mock = mocker.patch("IPython.terminal.embed.InteractiveShellEmbed.interact")
 
@@ -18,11 +34,11 @@ def test_interact(mocker: MockerFixture) -> None:
     interact_mock.assert_called_once_with()
 
 
-def test_interact_import_error(mocker: MockerFixture) -> None:
+def test_interact_no_ipython(mocker: MockerFixture) -> None:
     """
     must call builtin shell if no IPython available
     """
-    pytest.helpers.import_error("IPython.terminal.embed", ["InteractiveShellEmbed"], mocker)
+    mocker.patch("ahriman.application.interactive_shell.InteractiveShell.has_ipython", return_value=None)
     interact_mock = mocker.patch("code.InteractiveConsole.interact")
 
     shell = InteractiveShell()