From 245300ad92c3debbf4c79c702c52809ffff1f943 Mon Sep 17 00:00:00 2001
From: Liam Mitchell <liam.mitchell@mendix.com>
Date: Thu, 28 Aug 2025 13:58:50 +0200
Subject: [PATCH] fix: optional set calc

---
 workspaces/arborist/lib/optional-set.js  |  6 ++----
 workspaces/arborist/test/optional-set.js | 25 ++++++++++++------------
 2 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/workspaces/arborist/lib/optional-set.js b/workspaces/arborist/lib/optional-set.js
index 9f5184ea02442..76d557c0e52c5 100644
--- a/workspaces/arborist/lib/optional-set.js
+++ b/workspaces/arborist/lib/optional-set.js
@@ -29,10 +29,8 @@ const optionalSet = node => {
   }
 
   // now that we've hit the boundary, gather the rest of the nodes in
-  // the optional section.  that's the set of dependencies that are only
-  // depended upon by other nodes within the set, or optional dependencies
-  // from outside the set.
-  return gatherDepSet(set, edge => !edge.optional)
+  // the optional section that don't have dependents outside the set.
+  return gatherDepSet(set, edge => !set.has(edge.to))
 }
 
 module.exports = optionalSet
diff --git a/workspaces/arborist/test/optional-set.js b/workspaces/arborist/test/optional-set.js
index e639ea1450ef6..f28564554a71b 100644
--- a/workspaces/arborist/test/optional-set.js
+++ b/workspaces/arborist/test/optional-set.js
@@ -9,17 +9,18 @@ tree (PROD a, PROD c, OPT i)
 +-- a (OPT o)
 +-- b (PROD c)
 +-- c (OPT b)
-+-- o (PROD m)
-+-- m (PROD n)
++-- o (PROD m, OPT i)
++-- m (OPT n)
 +-- n ()
 +-- OPT i (PROD j)
 +-- j ()
 
 Gathering the optional set from:
-j: [i],
+j: [j, i],
 a: [],
-o: [m, n],
-b: []
+o: [o, m, n],
+m: [o, m, n],
+b: [b],
 */
 
 const tree = new Node({
@@ -38,8 +39,8 @@ const tree = new Node({
     ['a', [], ['o']],
     ['b', ['c'], []],
     ['c', [], ['b']],
-    ['o', ['m'], []],
-    ['m', ['n'], []],
+    ['o', ['m'], ['i']],
+    ['m', [], ['n']],
     ['n', [], []],
     ['i', ['j'], []],
     ['j', [], []],
@@ -83,11 +84,11 @@ t.equal(setO.has(nodeO), true, 'set o includes o')
 t.equal(setO.has(nodeM), true, 'set o includes m')
 t.equal(setO.has(nodeN), true, 'set o includes n')
 
-const setN = optionalSet(nodeO)
-t.equal(setN.size, 3, 'three nodes in n set')
-t.equal(setN.has(nodeO), true, 'set n includes o')
-t.equal(setN.has(nodeM), true, 'set n includes m')
-t.equal(setN.has(nodeN), true, 'set n includes n')
+const setM = optionalSet(nodeM)
+t.equal(setM.size, 3, 'three nodes in m set')
+t.equal(setM.has(nodeO), true, 'set m includes o')
+t.equal(setM.has(nodeM), true, 'set m includes m')
+t.equal(setM.has(nodeN), true, 'set m includes n')
 
 const setB = optionalSet(nodeB)
 t.equal(setB.size, 1, 'gathering from b is only b')