diff --git a/InvenTree/InvenTree/api_tester.py b/InvenTree/InvenTree/api_tester.py
index 992ecead21..c5d96e6bb3 100644
--- a/InvenTree/InvenTree/api_tester.py
+++ b/InvenTree/InvenTree/api_tester.py
@@ -49,32 +49,38 @@ class UserMixin:
 
         self.user.save()
 
-        for role in self.roles:
-            self.assignRole(role, self.roles == ['all'])
+        # Assign all roles if set
+        if self.roles == 'all':
+            self.assignRole()
+        # else filter the roles
+        else:
+            for role in self.roles:
+                self.assignRole(role)
 
         if self.auto_login:
             self.client.login(username=self.username, password=self.password)
 
-    def assignRole(self, role, assign_all: bool = False):
+    def assignRole(self, role = None, assign_all: bool = False):
         """
         Set the user roles for the registered user
         """
 
         # role is of the format 'rule.permission' e.g. 'part.add'
 
-        rule, perm = role.split('.')
+        if not assign_all:
+            rule, perm = role.split('.')
 
         for ruleset in self.group.rule_sets.all():
 
-            if ruleset.name == rule or assign_all:
+            if assign_all or ruleset.name == rule:
 
-                if perm == 'view' or assign_all:
+                if assign_all or perm == 'view':
                     ruleset.can_view = True
-                elif perm == 'change' or assign_all:
+                elif assign_all or perm == 'change':
                     ruleset.can_change = True
-                elif perm == 'delete' or assign_all:
+                elif assign_all or perm == 'delete':
                     ruleset.can_delete = True
-                elif perm == 'add' or assign_all:
+                elif assign_all or perm == 'add':
                     ruleset.can_add = True
 
                 ruleset.save()
diff --git a/InvenTree/InvenTree/test_api.py b/InvenTree/InvenTree/test_api.py
index 4a5e03ac5a..10e2305d07 100644
--- a/InvenTree/InvenTree/test_api.py
+++ b/InvenTree/InvenTree/test_api.py
@@ -20,7 +20,7 @@ class HTMLAPITests(InvenTreeTestCase):
     which raised an AssertionError when using the HTML API interface,
     while the regular JSON interface continued to work as expected.
     """
-    roles = ['all']
+    roles = 'all'
 
     def test_part_api(self):
         url = reverse('api-part-list')
diff --git a/InvenTree/company/test_views.py b/InvenTree/company/test_views.py
index 0c135aff88..a3ecd1651a 100644
--- a/InvenTree/company/test_views.py
+++ b/InvenTree/company/test_views.py
@@ -16,9 +16,7 @@ class CompanyViewTestBase(InvenTreeTestCase):
         'supplier_part',
     ]
 
-    roles = [
-        'all',
-    ]
+    roles = 'all'
 
 
 class CompanyViewTest(CompanyViewTestBase):
diff --git a/InvenTree/part/test_bom_export.py b/InvenTree/part/test_bom_export.py
index 38d9bb5db9..d78ced4b17 100644
--- a/InvenTree/part/test_bom_export.py
+++ b/InvenTree/part/test_bom_export.py
@@ -18,7 +18,7 @@ class BomExportTest(InvenTreeTestCase):
         'bom',
     ]
 
-    roles = ['all']
+    roles = 'all'
 
     def setUp(self):
         super().setUp()
diff --git a/InvenTree/part/test_views.py b/InvenTree/part/test_views.py
index 2971c032e0..f20fc3159f 100644
--- a/InvenTree/part/test_views.py
+++ b/InvenTree/part/test_views.py
@@ -17,7 +17,7 @@ class PartViewTestCase(TestCase):
         'supplier_part',
     ]
 
-    roles = ['all']
+    roles = 'all'
 
     def setUp(self):
         super().setUp()
diff --git a/InvenTree/plugin/base/integration/test_mixins.py b/InvenTree/plugin/base/integration/test_mixins.py
index d9be17fde0..9ccc99528f 100644
--- a/InvenTree/plugin/base/integration/test_mixins.py
+++ b/InvenTree/plugin/base/integration/test_mixins.py
@@ -260,7 +260,7 @@ class PanelMixinTests(TestCase):
         'stock',
     ]
 
-    roles = ['all']
+    roles = 'all'
 
     def test_installed(self):
         """Test that the sample panel plugin is installed"""
diff --git a/InvenTree/stock/test_views.py b/InvenTree/stock/test_views.py
index acea850046..dba39334de 100644
--- a/InvenTree/stock/test_views.py
+++ b/InvenTree/stock/test_views.py
@@ -18,7 +18,7 @@ class StockViewTestCase(InvenTreeTestCase):
         'stock',
     ]
 
-    roles = ['all']
+    roles = 'all'
 
 
 class StockListTest(StockViewTestCase):