Fix to not filter out empty modules from the Feature Tree (#6224)

src/lib/operations.test.ts

@@ -27,12 +27,31 @@ function userCall(name: string): Operation {
     sourceRange: defaultSourceRange(),
   }
 }
+
 function userReturn(): Operation {
   return {
     type: 'GroupEnd',
   }
 }
 
+function moduleBegin(name: string): Operation {
+  return {
+    type: 'GroupBegin',
+    group: {
+      type: 'ModuleInstance',
+      name,
+      moduleId: 0,
+    },
+    sourceRange: defaultSourceRange(),
+  }
+}
+
+function moduleEnd(): Operation {
+  return {
+    type: 'GroupEnd',
+  }
+}
+
 describe('operations filtering', () => {
   it('drops stdlib operations inside a user-defined function call', async () => {
     const operations = [
@@ -65,6 +84,25 @@ describe('operations filtering', () => {
     const actual = filterOperations(operations)
     expect(actual).toEqual([stdlib('std1'), stdlib('std2'), stdlib('std3')])
   })
+  it('does not drop module instances that contain no operations', async () => {
+    const operations = [
+      stdlib('std1'),
+      moduleBegin('foo'),
+      moduleEnd(),
+      stdlib('std2'),
+      moduleBegin('bar'),
+      moduleEnd(),
+      stdlib('std3'),
+    ]
+    const actual = filterOperations(operations)
+    expect(actual).toEqual([
+      stdlib('std1'),
+      moduleBegin('foo'),
+      stdlib('std2'),
+      moduleBegin('bar'),
+      stdlib('std3'),
+    ])
+  })
   it('preserves user-defined function calls at the end of the list', async () => {
     const operations = [stdlib('std1'), userCall('foo')]
     const actual = filterOperations(operations)