Fix Map#concat

philipp-spiess · philipp-spiess · commit d785d58eb776 · 2017-10-18T10:45:22.000+02:00
immutable-js#1373 made `Map#concat` an alias for `Map#merge` but defined the alias before `Map#merge` was defined, resulting in `Map#concat` being undefined. This fixes the issue and adds a regression test.
diff --git a/__tests__/Map.ts b/__tests__/Map.ts
@@ -129,6 +129,14 @@ describe('Map', () => {
     expect(m3.toObject()).toEqual({a: 'A', b: 'BB', c: 'C', wow: 'OO', d: 'DD'});
   });
 
+  it('concatenates two maps (alias for merge)', () => {
+    const m1 = Map({ a: 'A', b: 'B', c: 'C' });
+    const m2 = Map({ wow: 'OO', d: 'DD', b: 'BB' });
+    expect(m2.toObject()).toEqual({ wow: 'OO', d: 'DD', b: 'BB' });
+    const m3 = m1.concat(m2);
+    expect(m3.toObject()).toEqual({a: 'A', b: 'BB', c: 'C', wow: 'OO', d: 'DD'});
+  });
+
   it('accepts null as a key', () => {
     const m1 = Map<any, any>();
     const m2 = m1.set(null, 'null');
diff --git a/src/Map.js b/src/Map.js
@@ -170,7 +170,7 @@ export const MapPrototype = Map.prototype;
 MapPrototype[IS_MAP_SENTINEL] = true;
 MapPrototype[DELETE] = MapPrototype.remove;
 MapPrototype.removeAll = MapPrototype.deleteAll;
-MapPrototype.concat = MapPrototype.merge;
+MapPrototype.concat = merge;
 MapPrototype.setIn = setIn;
 MapPrototype.removeIn = MapPrototype.deleteIn = deleteIn;
 MapPrototype.update = update;
