Move Jump's default condition to class level field, add unit test

No functional changes intended. I was hunting a transient bug in
Jump which turned out to be a "feature" when executing jumps under
PyCharm's debugger.

Re spine-tools/Spine-Toolbox#2925

spine_engine/project_item/connection.py

@@ -589,20 +589,22 @@ def from_dict(cls, connection_dict):
 class Jump(ConnectionBase):
     """Represents a conditional jump between two project items."""
 
+    _DEFAULT_CONDITION = {"type": "python-script", "script": "exit(1)", "specification": ""}
+
     def __init__(
-        self, source_name, source_position, destination_name, destination_position, condition={}, cmd_line_args=()
+        self, source_name, source_position, destination_name, destination_position, condition=None, cmd_line_args=()
     ):
         """
         Args:
             source_name (str): source project item's name
             source_position (str): source anchor's position
             destination_name (str): destination project item's name
             destination_position (str): destination anchor's position
-            condition (dict): jump condition
+            condition (dict, optional): jump condition
+            cmd_line_args (Iterable of str): command line arguments
         """
         super().__init__(source_name, source_position, destination_name, destination_position)
-        default_condition = {"type": "python-script", "script": "exit(1)", "specification": ""}
-        self.condition = condition if condition else default_condition
+        self.condition = condition if condition is not None else self._DEFAULT_CONDITION
         self._resources_from_source = set()
         self._resources_from_destination = set()
         self.cmd_line_args = list(cmd_line_args)

tests/project_item/test_connection.py

@@ -11,11 +11,12 @@
 ######################################################################################################################
 """ Uni tests for the ``connection`` module. """
 import os.path
+import pathlib
 from tempfile import TemporaryDirectory
 import unittest
 from unittest.mock import Mock
 from spine_engine.project_item.connection import Connection, FilterSettings, Jump
-from spine_engine.project_item.project_item_resource import database_resource
+from spine_engine.project_item.project_item_resource import LabelArg, database_resource, file_resource
 from spinedb_api import DatabaseMapping, import_alternatives, import_entity_classes, import_scenarios
 from spinedb_api.filters.scenario_filter import SCENARIO_FILTER_TYPE
 
@@ -169,6 +170,31 @@ def test_counter_passed_to_condition(self):
         jump.make_logger(Mock())
         self.assertTrue(jump.is_condition_true(23))
 
+    def test_command_line_args_with_whitespace_are_not_broken_into_tokens(self):
+        # Curiously, this test fails when run under PyCharm's debugger.
+        with TemporaryDirectory() as temp_dir:
+            path = pathlib.Path(temp_dir) / "path with spaces" / "file name.txt"
+            condition = {
+                "type": "python-script",
+                "script": "\n".join(
+                    (
+                        "from pathlib import Path",
+                        "import sys",
+                        "if len(sys.argv) != 3:",
+                        "    exit(1)",
+                        f"expected_path = Path(r'{str(path)}').resolve()",
+                        "if Path(sys.argv[1]).resolve() != expected_path:",
+                        "    exit(1)",
+                        "exit(0 if int(sys.argv[2]) == 23 else 1)",
+                    )
+                ),
+            }
+            jump = Jump("source", "bottom", "destination", "top", condition, [LabelArg("arg_label")])
+            resource = file_resource("provider: unit test", str(path), "arg_label")
+            jump.receive_resources_from_source([resource])
+            jump.make_logger(Mock())
+            self.assertTrue(jump.is_condition_true(23))
+
     def test_dictionary(self):
         jump = Jump("source", "bottom", "destination", "top", {"type": "python-script", "script": "exit(23)"})
         jump_dict = jump.to_dict()