fix: Support seq-of-maps merge key values (#321)

Fixes #320

Author: jjkavalam

src/nodes/addPairToJSMap.ts

@@ -16,6 +16,7 @@ export function addPairToJSMap(
   { key, value }: Pair
 ) {
   if (ctx && ctx.doc.schema.merge && isMergeKey(key)) {
+    value = isAlias(value) ? value.resolve(ctx.doc) : value
     if (isSeq(value)) for (const it of value.items) mergeToJSMap(ctx, map, it)
     else if (Array.isArray(value))
       for (const it of value) mergeToJSMap(ctx, map, it)

tests/doc/anchors.js

@@ -225,6 +225,16 @@ describe('merge <<', () => {
     ])
   })
 
+  test('alias is associated with a sequence', () => {
+    const res = YAML.parse(
+      '- &items [{ a: A }, { b: B }]\n- { <<: *items, c: C }',
+      {
+        merge: true
+      }
+    )
+    expect(res[1]).toEqual({ a: 'A', b: 'B', c: 'C' })
+  })
+
   describe('non-alias merges', () => {
     test('single map', () => {
       const res = YAML.parse('{ <<: { a: A }, b: B }', { merge: true })