Refactor shift constraints in tests to use new constraint classes

- Updated test cases in `test_workers.py` to replace dictionary-based constraints with instances of `PreShiftConstraint`, `PostShiftConstraint`, and `MaxShiftsPerWeekConstraint`.
- Added a new test `test_worker_assign_as_block_preference2` to verify worker preferences for block assignments.
- Marked tests as slow where appropriate to improve test suite performance.

test/test_limit_constraints.py

@@ -1,6 +1,6 @@
 import pytest
 import datetime
-from rota.shifts import RotaBuilder, SingleShift, days
+from rota.shifts import MinimumGradeNumberConstraint, RequireRemoteSitePresenceConstraint, RotaBuilder, SingleShift, days, LimitGradeNumberConstraint
 from rota.workers import Worker
 
 @pytest.fixture
@@ -33,7 +33,7 @@ def test_constraint_limit_grades(limit_constraint_rota):
             balance_offset=60,
             workers_required=4,
             force_as_block=True,
-            constraint=[{"name": "limit_grade_number", "options": {2: 1}}],
+            constraints=[LimitGradeNumberConstraint(grade=2, max_number=1)]
         ),
     )
     Rota.build_and_solve(options={"ratio": 0.01})
@@ -60,7 +60,7 @@ def test_constraint_limit_grades2(limit_constraint_rota):
             balance_offset=40,
             workers_required=4,
             force_as_block=True,
-            constraint=[{"name": "limit_grade_number", "options": {3: 1}}],
+            constraints=[LimitGradeNumberConstraint(grade=3, max_number=1)],
         ),
     )
     Rota.constraint_options["balance_shifts_quadratic"] = True
@@ -96,7 +96,7 @@ def test_constraint_limit_grades3(limit_constraint_rota):
             balance_offset=60,
             workers_required=4,
             force_as_block=True,
-            constraint=[{"name": "limit_grade_number", "options": {2: 3, 3: 1}}],
+            constraints=[LimitGradeNumberConstraint(grade=2, max_number=3), LimitGradeNumberConstraint(grade=3, max_number=1)],
         ),
     )
     Rota.constraint_options["balance_shifts_quadratic"] = True
@@ -124,7 +124,7 @@ def test_constraint_limit_grades4(limit_constraint_rota):
             balance_offset=40,
             workers_required=4,
             force_as_block=True,
-            constraint=[{"name": "limit_grade_number", "options": {2: 4, 3: 0}}],
+            constraints=[LimitGradeNumberConstraint(grade=2, max_number=4), LimitGradeNumberConstraint(grade=3, max_number=0)],
         ),
     )
     Rota.constraint_options["balance_shifts_quadratic"] = True
@@ -143,7 +143,7 @@ def test_constraint_minimum_grades(limit_constraint_rota):
             balance_offset=40,
             workers_required=1,
             force_as_block=True,
-            constraint=[{"name": "minimum_grade_number", "options": (3, 1)}],
+            constraints=[MinimumGradeNumberConstraint(grade=3, min_number=1)],
         ),
     )
     Rota.constraint_options["balance_shifts_quadratic"] = True
@@ -170,7 +170,7 @@ def test_constraint_minimum_grades2(limit_constraint_rota):
             balance_offset=40,
             workers_required=4,
             force_as_block=True,
-            constraint=[{"name": "minimum_grade_number", "options": (3, 3)}],
+            constraints=[MinimumGradeNumberConstraint(grade=3, min_number=3)],
         ),
     )
     Rota.constraint_options["balance_shifts_quadratic"] = True
@@ -197,7 +197,7 @@ def test_constraint_minimum_grades3(limit_constraint_rota):
             balance_offset=40,
             workers_required=4,
             force_as_block=True,
-            constraint=[{"name": "minimum_grade_number", "options": (3, 0)}],
+            constraints=[MinimumGradeNumberConstraint(grade=3, min_number=0)],
         ),
     )
     Rota.constraint_options["balance_shifts_quadratic"] = True
@@ -217,7 +217,7 @@ def test_constraint_minimum_grades_no_valid_worker(limit_constraint_rota):
             balance_offset=40,
             workers_required=4,
             force_as_block=True,
-            constraint=[{"name": "minimum_grade_number", "options": (4, 1)}],
+            constraints=[MinimumGradeNumberConstraint(grade=4, min_number=1)],
         ),
     )
     Rota.constraint_options["balance_shifts_quadratic"] = True
@@ -236,11 +236,8 @@ def test_constraint_require_remote_site_presence_week(limit_constraint_rota):
             balance_offset=40,
             workers_required=2,
             force_as_block=True,
-            constraint=[
-                {
-                    "name": "require_remote_site_presence_week",
-                    "options": ("group1", 2),
-                }
+            constraints=[
+                RequireRemoteSitePresenceConstraint(site="group1", required_number=2)
             ],
         ),
     )
@@ -272,11 +269,8 @@ def test_constraint_require_remote_site_presence_week2(limit_constraint_rota):
             balance_offset=20,
             workers_required=3,
             force_as_block=True,
-            constraint=[
-                {
-                    "name": "require_remote_site_presence_week",
-                    "options": ("group1", 2),
-                }
+            constraints=[
+                RequireRemoteSitePresenceConstraint(site="group1", required_number=2)
             ],
         ),
     )
@@ -304,11 +298,8 @@ def test_constraint_require_remote_site_presence_week3(limit_constraint_rota):
             balance_offset=20,
             workers_required=3,
             force_as_block=True,
-            constraint=[
-                {
-                    "name": "require_remote_site_presence_week",
-                    "options": ("group2", 1),
-                }
+            constraints=[
+                RequireRemoteSitePresenceConstraint(site="group2", required_number=1)
             ],
         ),
     )