diff --git a/pyproject.toml b/pyproject.toml
index ddde265..eec9556 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -10,6 +10,7 @@ z3-solver = "*"
 pydantic = "*"
 typer = "*"
 python-dateutil = "^2.8.2"
+pytest-bdd = "^6.0.1"
 
 [tool.poetry.dev-dependencies]
 ipython = "*"
diff --git a/tests/features/explicit-deny.feature b/tests/features/explicit-deny.feature
new file mode 100644
index 0000000..7503cb1
--- /dev/null
+++ b/tests/features/explicit-deny.feature
@@ -0,0 +1,38 @@
+Feature: Explicit Deny
+	Background:
+		Given I'm using arn:aws:iam::111111111111:role/source-deny with the policy:
+			[{
+				"Effect": "Deny",
+				"Action": "*",
+				"Resource": "*"
+			}]
+
+	Scenario: Same account root ARN trust
+		Given I have the resource arn:aws:iam::111111111111:role/target with the trust policy:
+			[{
+				"Effect": "Allow",
+				"Principal": { "AWS": "arn:aws:iam::111111111111:root" },
+				"Action": "sts:AssumeRole"
+			}]
+		When I call sts:AssumeRole on the resource
+		Then Access should be denied
+
+	Scenario: Same account explicit ARN trust
+		Given I have the resource arn:aws:iam::111111111111:role/target with the trust policy:
+			[{
+				"Effect": "Allow",
+				"Principal": { "AWS": "arn:aws:iam::111111111111:role/source-deny" },
+				"Action": "sts:AssumeRole"
+			}]
+		When I call sts:AssumeRole on the resource
+		Then Access should be denied
+
+	Scenario: Cross account explicit ARN trust
+		Given I have the resource arn:aws:iam::999999999999:role/target with the trust policy:
+			[{
+			"Effect": "Allow",
+			"Principal": { "AWS": "arn:aws:iam::111111111111:role/source-deny" },
+			"Action": "sts:AssumeRole"
+			}]
+		When I call sts:AssumeRole on the resource
+		Then Access should be denied
\ No newline at end of file
diff --git a/tests/features/root-trust.feature b/tests/features/root-trust.feature
new file mode 100644
index 0000000..7d03801
--- /dev/null
+++ b/tests/features/root-trust.feature
@@ -0,0 +1,18 @@
+Feature: Root Trust
+	Background:
+		Given I'm using arn:aws:iam::111111111111:role/source with the policy:
+			[{
+				"Effect": "Allow",
+				"Action": "sts:AssumeRole",
+				"Resource": "*"
+			}]
+
+	Scenario: Same account AssumeRole request.
+		Given I have the resource arn:aws:iam::111111111111:role/target with the trust policy:
+			[{
+				"Effect": "Allow",
+				"Principal": { "AWS": "arn:aws:iam::111111111111:root" },
+				"Action": "sts:AssumeRole"
+			}]
+		When I call sts:AssumeRole on the resource
+		Then Access should be allowed
\ No newline at end of file
diff --git a/tests/fixtures/role.py b/tests/fixtures/role.py
new file mode 100644
index 0000000..0e58ea9
--- /dev/null
+++ b/tests/fixtures/role.py
@@ -0,0 +1,17 @@
+import pytest
+
+from iamspy import Model
+
+
+@pytest.fixture
+def model() -> Model:
+    return Model()
+
+
+@pytest.fixture
+def req():
+    return {
+        "source": "",
+        "action": "",
+        "resource": "",
+    }
diff --git a/tests/test_bdd.py b/tests/test_bdd.py
new file mode 100644
index 0000000..cda06aa
--- /dev/null
+++ b/tests/test_bdd.py
@@ -0,0 +1,70 @@
+import json
+from datetime import datetime
+
+from iamspy.iam import RoleDetail, Document, Policy, RoleLastUse, ResourcePolicy
+from iamspy.parse import _parse_role, parse_resource_policy
+from pytest_bdd import scenarios, given, when, then, parsers
+from pytest_bdd.parsers import parse
+
+from .fixtures.role import *
+
+scenarios("features")
+
+@pytest.fixture
+def source() -> 'RoleDetail':
+    return RoleDetail(
+        Path="/",
+        RoleName="source",
+        CreateDate=datetime.now(),
+        RoleLastUsed=RoleLastUse(LastUsedDate=datetime.now(), Region="us-east-1"),
+        RoleId="AORAXXXXXXXXXXXXXXXXX",
+        Arn=f"arn:aws:iam::111111111111:role/source",
+        AssumeRolePolicyDocument=Document(),
+        InstanceProfileList=[],
+        RolePolicyList=[],
+    )
+
+
+@given(parsers.parse("I'm using {arn} with the policy:\n{policy}"))  # Step alias
+def set_source(model, req, source, arn, policy):
+    source.Arn = arn
+    source.RoleName = arn.split(':')[5].split("/")[-1]
+    source.RolePolicyList.append(Policy(
+        PolicyName="identity_policy",
+        PolicyDocument=Document(Statement=json.loads(policy)),
+    ))
+
+
+@pytest.fixture
+def resource():
+    return ResourcePolicy(
+        Resource="target",
+        Policy=Document(),
+        Account="111111111111",
+    )
+
+
+@given(parse("I have the resource {arn} with the trust policy:\n{policy}"))
+def set_resource(resource, arn, policy):
+    resource.Resource = arn
+    resource.Account = arn.split(':')[4]
+    resource.Policy = Document(Statement=json.loads(policy))
+
+
+@when(parsers.parse("I call {action}"))
+def call(req, model, source, action, resource):
+    model.solver.add(*_parse_role(None, source))
+    model.solver.add(*parse_resource_policy(resource.Resource, resource.Policy, resource.Account))
+    req["source"] = source.Arn
+    req["action"] = action
+    req["resource"] = resource.Resource
+
+
+@then(parsers.parse("Access should be allowed"))
+def allowed(model, req):
+    assert model.can_i(**req)
+
+
+@then(parsers.parse("Access should be denied"))
+def denied(model, req):
+    assert not model.can_i(**req, strict_conditions=True)
\ No newline at end of file