diff --git a/poetry.lock b/poetry.lock
index e546e71..5e01db4 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -291,13 +291,13 @@ uvloop = ["uvloop (>=0.15.2)"]
 
 [[package]]
 name = "certifi"
-version = "2024.6.2"
+version = "2024.7.4"
 description = "Python package for providing Mozilla's CA Bundle."
 optional = false
 python-versions = ">=3.6"
 files = [
-    {file = "certifi-2024.6.2-py3-none-any.whl", hash = "sha256:ddc6c8ce995e6987e7faf5e3f1b02b302836a0e5d98ece18392cb1a36c72ad56"},
-    {file = "certifi-2024.6.2.tar.gz", hash = "sha256:3cd43f1c6fa7dedc5899d69d3ad0398fd018ad1a17fba83ddaf78aa46c747516"},
+    {file = "certifi-2024.7.4-py3-none-any.whl", hash = "sha256:c198e21b1289c2ab85ee4e67bb4b4ef3ead0892059901a8d5b622f24a1101e90"},
+    {file = "certifi-2024.7.4.tar.gz", hash = "sha256:5a1e7645bc0ec61a09e26c36f6106dd4cf40c6db3a1fb6352b0244e7fb057c7b"},
 ]
 
 [[package]]
@@ -3026,6 +3026,23 @@ pytest = ">=4.6"
 [package.extras]
 testing = ["fields", "hunter", "process-tests", "pytest-xdist", "six", "virtualenv"]
 
+[[package]]
+name = "pytest-mock"
+version = "3.14.0"
+description = "Thin-wrapper around the mock package for easier use with pytest"
+optional = false
+python-versions = ">=3.8"
+files = [
+    {file = "pytest-mock-3.14.0.tar.gz", hash = "sha256:2719255a1efeceadbc056d6bf3df3d1c5015530fb40cf347c0f9afac88410bd0"},
+    {file = "pytest_mock-3.14.0-py3-none-any.whl", hash = "sha256:0b72c38033392a5f4621342fe11e9219ac11ec9d375f8e2a0c164539e0d70f6f"},
+]
+
+[package.dependencies]
+pytest = ">=6.2.5"
+
+[package.extras]
+dev = ["pre-commit", "pytest-asyncio", "tox"]
+
 [[package]]
 name = "pytest-subtests"
 version = "0.12.1"
@@ -4982,4 +4999,4 @@ multidict = ">=4.0"
 [metadata]
 lock-version = "2.0"
 python-versions = "^3.10"
-content-hash = "8d6b39c4e1ed3668b4e342451702a4302620923f7f8df24a0f9cd86a26a0bf41"
+content-hash = "3b9b509b05c7ead59a8f1074b097752fcc1253dfbbb4eb69f4d49403fc030a61"
diff --git a/pyproject.toml b/pyproject.toml
index 6498cfa..5c17394 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -16,6 +16,7 @@ pyyaml = "^6.0.1"
 jinja2 = "^3.1.4"
 rustworkx = "^0.14.2"
 matplotlib = "^3.9.0"
+certifi = "^2024.7.4"
 
 
 [tool.poetry.group.dev.dependencies]
@@ -26,6 +27,7 @@ pytest-cov = "^4.1.0"
 pytest-timeout = "^2.2.0"
 pytest-subtests = "^0.12.1"
 black = {extras = ["jupyter"], version = "^24.4.2"}
+pytest-mock = "^3.14.0"
 
 [tool.poetry.group.all]
 optional = true
diff --git a/tests/problem_fixtures.py b/tests/problem_fixtures.py
index 72cde50..4d565f3 100644
--- a/tests/problem_fixtures.py
+++ b/tests/problem_fixtures.py
@@ -1086,10 +1086,8 @@ def rover_line_fully_specified_1():
             (available rover1)
             (available rover2)
             (available rover3)
-            (at lander1 site1)
-            (at lander2 site6)
-            (visible_from lander1 site1)
-            (visible_from lander2 site6)
+            (at_lander lander1 site1)
+            (at_lander lander2 site6)
             (empty store1)
             (full store2)
             (store_of store1 rover1)
@@ -1135,10 +1133,8 @@ def rover_line_fully_specified_1():
                 (at rover1 site6)
                 (at rover2 site6)
                 (at rover3 site6)
-                (at lander1 site1)
-                (at lander2 site6)
-                (visible_from lander1 site1)
-                (visible_from lander2 site6)
+                (at_lander lander1 site1)
+                (at_lander lander2 site6)
                 (empty store1)
                 (full store2)
                 (store_of store1 rover1)
@@ -1245,10 +1241,8 @@ def rover_line_1():
             (available rover1)
             (available rover2)
             (available rover3)
-            (at lander1 site1)
-            (at lander2 site6)
-            (visible_from lander1 site1)
-            (visible_from lander2 site6)
+            (at_lander lander1 site1)
+            (at_lander lander2 site6)
         )
         (:goal
             (and
@@ -1296,8 +1290,8 @@ def rover_line_2():
             (available rover1)
             (available rover2)
             (available rover3)
-            (at lander1 site1)
-            (at lander2 site6)
+            (at_lander lander1 site1)
+            (at_lander lander2 site6)
         )
         (:goal
             (and