Adding overloaded methods to handle Parent object reference using token and syncing the id on the child

src/classes/sfab_FabricatedSObject.cls

@@ -28,11 +28,35 @@ public virtual class sfab_FabricatedSObject {
         nodes.add(new sfab_ParentRelationshipNode(relationshipName, fabricatedParent));
         return this;
     }
+
+    public sfab_FabricatedSObject setParent(Schema.SObjectField field, sfab_FabricatedSObject fabricatedParent) {
+        nodes.add(new sfab_ParentRelationshipNode(field, fabricatedParent));
+        return this;
+    }
+
+    public sfab_FabricatedSObject setParent(Schema.SObjectField field, sfab_FabricatedSObject fabricatedParent, Schema.SObjectField parentIdField) {
+        Object parentId = fabricatedParent.getFieldValue(parentIdField);
+        if(parentId != null) setField(field, parentId);
+
+        nodes.add(new sfab_ParentRelationshipNode(field, fabricatedParent));
+        return this;
+    }
 
     public sfab_FabricatedSObject setChildren(String relationshipName, List<sfab_FabricatedSObject> fabricatedChildren) {
         nodes.add(new sfab_ChildRelationshipNode(relationshipName, fabricatedChildren));
         return this;
     }
+
+    public Object getFieldValue(Schema.SObjectField field) {
+        for(sfab_FabricatedSObjectNode node : nodes) {
+            if(node instanceOf sfab_FieldValuePairNode) {
+                sfab_FieldValuePairNode theNode = ((sfab_FieldValuePairNode) node);
+                if(theNode.field == field) return theNode.value;
+            }
+        }
+
+        return null;
+    }
 
     public SObject toSObject() {
         return (SObject)JSON.deserialize(JSON.serialize(serialize()), sType);

src/classes/sfab_FabricatedSObjectTest.cls

@@ -48,11 +48,41 @@ private class sfab_FabricatedSObjectTest {
         fabricatedSObject.setParent('Account', new sfab_FabricatedSObject(Account.class));
         System.assertEquals(1, fabricatedSObject.nodes.size());
     }
+
+    @isTest
+    private static void setParentByToken_expectFieldAddedToNodes() {
+        sfab_FabricatedSObject fabricatedSObject = new sfab_FabricatedSObject(Opportunity.class);
+        fabricatedSObject.setParent(Opportunity.AccountId, new sfab_FabricatedSObject(Account.class));
+        System.assertEquals(1, fabricatedSObject.nodes.size());
+    }
+
+    @isTest
+    private static void setParentWithId_expectFieldAddedToNodes() {
+        sfab_FabricatedSObject fabricatedParentSObject = new sfab_FabricatedSObject(Account.class);
+        fabricatedParentSObject.setField(Account.Id, 'Id-1');
+        sfab_FabricatedSObject fabricatedSObject = new sfab_FabricatedSObject(Opportunity.class);
+        fabricatedSObject.setParent(Opportunity.AccountId, fabricatedParentSObject, Account.Id);
+        System.assertEquals(2, fabricatedSObject.nodes.size());
+        System.assertEquals('Id-1', fabricatedSObject.getFieldValue(Opportunity.AccountId));
+    }
 
     @isTest
     private static void setChildren_expectFieldAdded() {
         sfab_FabricatedSObject fabricatedSObject = new sfab_FabricatedSObject(Account.class);
         fabricatedSObject.setChildren('Opportunites', new List<sfab_FabricatedSObject>());
         System.assertEquals(1, fabricatedSObject.nodes.size());
     }
+
+    @isTest
+    private static void getFieldValue_expectValue() {
+        sfab_FabricatedSObject fabricatedSObject = new sfab_FabricatedSObject(Account.class);
+        fabricatedSObject.setField(Account.Id, 'Id-1');
+        System.assertEquals('Id-1', fabricatedSObject.getFieldValue(Account.Id));
+    }
+
+    @isTest
+    private static void getFieldValue_expectNotFound() {
+        sfab_FabricatedSObject fabricatedSObject = new sfab_FabricatedSObject(Account.class);
+        System.assertEquals(null, fabricatedSObject.getFieldValue(Account.Id));
+    }
 }

src/classes/sfab_FieldValuePairNode.cls

@@ -1,6 +1,6 @@
 public class sfab_FieldValuePairNode implements sfab_FabricatedSObjectNode {
-    protected Schema.SObjectField field;
-    protected Object value;
+    public Schema.SObjectField field {get; private set;}
+    public Object value {get; private set;}
 
     public sfab_FieldValuePairNode(Schema.SObjectField field, Object value) {
         this.field = field;

src/classes/sfab_ParentRelationshipNode.cls

@@ -6,6 +6,10 @@ public class sfab_ParentRelationshipNode implements sfab_FabricatedSObjectNode {
         this.fieldName = fieldName;
         this.parent = parent;
     }
+
+    public sfab_ParentRelationshipNode(Schema.SObjectField field, sfab_FabricatedSObject parent) {
+        this(field.getDescribe().getRelationshipName(), parent);
+    }
 
     public Map<String, Object> serialize() {
         return new Map<String, Object> { fieldName => parent.serialize() };