chore: work with singular child type

src/convert/transformers/decomposedPermissionSetTransformer.ts

@@ -102,7 +102,7 @@ export class DecomposedPermissionSetTransformer extends BaseMetadataTransformer
     const preparedMetadata = composedMetadata
       .filter(hasChildTypeId)
       .map(addChildType)
-      .map((c) => toInfoContainer(mergeWith)(component)(c.childType)(c.tagValue as JsonMap))
+      .map((child) => toInfoContainer(mergeWith)(component)(child.childType)(child.tagValue as JsonMap))
       .filter(forceIgnoreAllowsComponent(forceIgnore));
 
     const writeInfosForChildren = combineChildWriteInfos(
@@ -249,8 +249,9 @@ const toInfoContainer =
   (parent: SourceComponent) =>
   (childType: MetadataType) =>
   (tagValue: JsonMap): InfoContainer => {
+    const tagEntry: JsonMap[] = Array.isArray(tagValue) ? tagValue : [tagValue];
     const entryName = childType.directoryName
-      ? ((tagValue as unknown as JsonMap[]).at(0)?.[childType.uniqueIdElement!] as string).split('.')[0]
+      ? (tagEntry.at(0)?.[childType.uniqueIdElement!] as string).split('.')[0]
       : parent.name;
     return {
       parentComponent: parent,

test/convert/transformers/decompoedPermissionSetTransformer.test.ts

@@ -13,6 +13,7 @@ import { presetMap } from '../../../src/registry/presets/presetMap';
 import { DecomposedPermissionSetTransformer } from '../../../src/convert/transformers/decomposedPermissionSetTransformer';
 import {
   MD_FORMAT_PS,
+  MD_FORMAT_PS_ONE_CHILD,
   ONLY_PS_PARENT,
   SOURCE_FORMAT_PS,
 } from '../../mock/type-constants/decomposedPermissionSetConstant';
@@ -36,6 +37,19 @@ describe('DecomposedPermissionSetTransformer', () => {
         expect(result[3].output).to.match(/objectSettings[\\/]Broker__c.objectSettings-meta.xml$/);
         expect(result[4].output).to.match(/myPS.permissionset-meta.xml$/);
       });
+
+      it('multiple children combined, and some written to individual files', async () => {
+        const component = MD_FORMAT_PS_ONE_CHILD;
+        const xf = new DecomposedPermissionSetTransformer(regAcc);
+        const result = await xf.toSourceFormat({ component });
+        expect(result).to.have.length(2);
+        result.map((l) => {
+          expect(l.output).to.include(join('main', 'default', 'permissionsets'));
+        });
+        expect(result[0].output).to.match(/objectSettings[\\/]Case.objectSettings-meta.xml$/);
+        expect(result[1].output).to.match(/myPS.permissionset-meta.xml$/);
+      });
+
       it('merge component in defaultDir', async () => {
         const component = MD_FORMAT_PS;
         const xf = new DecomposedPermissionSetTransformer(regAcc);

test/mock/type-constants/decomposedPermissionSetConstant.ts

@@ -186,6 +186,40 @@ export const MD_FORMAT_PS = new SourceComponent(
   ])
 );
 
+export const MD_FORMAT_PS_ONE_CHILD = new SourceComponent(
+  {
+    name: 'myPS',
+    type: permissionSet,
+    xml: join('permissionsets', MDAPI_XML_NAME),
+  },
+  new VirtualTreeContainer([
+    {
+      dirPath: 'permissionsets',
+      children: [
+        {
+          name: MDAPI_XML_NAME,
+          data: Buffer.from(`<?xml version="1.0" encoding="UTF-8" ?>
+<PermissionSet xmlns="http://soap.sforce.com/2006/04/metadata">
+    <description>This PS has only one object permission</description>
+    <hasActivationRequired>true</hasActivationRequired>
+    <label>test</label>
+    <license>testing</license>
+    <objectPermissions>
+        <allowCreate>false</allowCreate>
+        <allowDelete>false</allowDelete>
+        <allowEdit>false</allowEdit>
+        <allowRead>true</allowRead>
+        <modifyAllRecords>false</modifyAllRecords>
+        <object>Case</object>
+        <viewAllRecords>true</viewAllRecords>
+    </objectPermissions>
+</PermissionSet>`),
+        },
+      ],
+    },
+  ])
+);
+
 export const SOURCE_FORMAT_PS = new SourceComponent(
   {
     name: 'myPS',