My progress so far-- constraint is likely done, test files still need…

… work because I am still figuring out oscal syntax

src/validations/constraints/content/ssp-network-component-has-connection-security-prop-INVALID.xml

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<system-security-plan xmlns="http://csrc.nist.gov/ns/oscal/1.0"
+                      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+                      xsi:schemaLocation="http://csrc.nist.gov/ns/oscal/1.0 https://github.com/usnistgov/OSCAL/releases/download/v1.1.2/oscal_ssp_schema.xsd"
+                      uuid="12345678-1234-4321-8765-123456789012">
+      <component uuid="69988666-0000-4000-9000-000000100006" type="interconnection">
+        <title>External API Connection</title>
+        <description>
+          <p>Secure connection to an external API for data enrichment.</p>
+        </description>
+        <!--Error: interconnection-security property not defined for an interconnection component-->
+        <!-- <prop name="interconnection-security" value="vpn" ns="https://fedramp.gov/ns/oscal"/> -->
+        <prop name="interconnection-direction" value="in/out" ns="https://fedramp.gov/ns/oscal"/>
+        <status state="operational"/>
+        <responsible-role role-id="system-admin">
+          <party-uuid>11111111-0000-4000-9000-000000000001</party-uuid>
+        </responsible-role>
+        <remarks>
+          <p>This connection is used for secure data exchange with external systems.</p>
+        </remarks>
+      </component>
+

src/validations/constraints/fedramp-external-constraints.xml

@@ -542,6 +542,11 @@
                 <formal-name>Leveraged Authorization Has System Identifier</formal-name>
                 <prop namespace="https://docs.oasis-open.org/sarif/sarif/v2.1.0" name="help-url" value="https://automate.fedramp.gov/documentation/ssp/4-ssp-template-to-oscal-mapping/#leveraged-fedramp-authorized-services"/>
                 <message>A FedRAMP SSP MUST define exactly one system identifier for each leveraged authorization entry.</message>
+			</expect>
+            <expect id="network-component-has-connection-security-prop" target="//component[(@type='service' and not(./prop[@name='leveraged-authorization-uuid']) and ./prop[@name='implementation-point' and @value='external']) or (@type='interconnection') or (@type='service' and ./prop[@name='implementation-point' and @value='internal'] and ./prop[@name='direction']) or (@type='software' and ./prop[@name='asset-type' and @value='cli'] and ./prop[@name='direction'])]" test="count(./prop[@name='interconnection-security' and @ns='http://fedramp.gov/ns/oscal']) >= 1" level="ERROR">
+				<formal-name>Network Component Has Connection Security Property</formal-name>
+				<prop namespace="https://docs.oasis-open.org/sarif/sarif/v2.1.0" name="help-url" value="https://automate.fedramp.gov/documentation/ssp/5-attachments/#system-inventory-approach"/>
+				<message>All network components in a FedRAMP SSP system implementation MUST define at least one interconnection security property</message>
             </expect>
 		</constraints>
 	</context>    

src/validations/constraints/unit-tests/network-component-has-connection-security-prop-FAIL.yaml

@@ -0,0 +1,9 @@
+test-case:
+  name: Negative Test for network-component-has-connection-security-prop
+  description: >-
+    This test case validates the behavior of constraint
+    network-component-has-connection-security-prop
+  content: ../content/ssp-network-component-has-connection-security-prop-INVALID.xml
+  expectations:
+    - constraint-id: network-component-has-connection-security-prop
+      result: fail

src/validations/constraints/unit-tests/network-component-has-connection-security-prop-PASS.yaml

@@ -0,0 +1,9 @@
+test-case:
+  name: Positive Test for network-component-has-connection-security-prop
+  description: >-
+    This test case validates the behavior of constraint
+    network-component-has-connection-security-prop
+  content: ../content/ssp-all-VALID.xml
+  expectations:
+    - constraint-id: network-component-has-connection-security-prop
+      result: pass