add flush to remote connection

.changeset/sour-timers-fail.md

@@ -0,0 +1,5 @@
+---
+'@remote-dom/core': minor
+---
+
+add flush method to BatchingRemoteConnection

packages/core/source/elements/connection.ts

@@ -25,20 +25,24 @@ export class BatchingRemoteConnection {
   }
 
   mutate(records: any[]) {
-    let queued = this.#queued;
+    this.#queued ??= [];
+    this.#queued.push(...records);
 
-    if (queued) {
-      queued.push(...records);
+    this.#batch(() => {
+      if (this.#queued) {
+        this.#connection.mutate(this.#queued);
+        this.#queued = undefined;
+      }
+    });
+  }
+
+  flush() {
+    if (!this.#queued) {
       return;
     }
 
-    queued = [...records];
-    this.#queued = queued;
-
-    this.#batch(() => {
-      this.#connection.mutate(queued);
-      this.#queued = undefined;
-    });
+    this.#connection.mutate(this.#queued);
+    this.#queued = undefined;
   }
 }
 

packages/core/source/elements/tests/connection.test.ts

@@ -0,0 +1,64 @@
+import '../../polyfill.ts';
+
+import {describe, expect, it, vi, type MockedObject} from 'vitest';
+
+import {BatchingRemoteConnection, RemoteConnection} from '../../elements';
+
+describe('BatchingRemoteConnection', () => {
+  it('batches mutations', async () => {
+    const connection = createRemoteConnectionSpy();
+    const batchingConnection = new BatchingRemoteConnection(connection);
+
+    batchingConnection.mutate([1, 2, 3]);
+    batchingConnection.mutate([4, 5, 6]);
+
+    expect(connection.mutate).not.toHaveBeenCalled();
+
+    await waitOneTick();
+
+    expect(connection.mutate).toHaveBeenCalledTimes(1);
+    expect(connection.mutate).toHaveBeenCalledWith([1, 2, 3, 4, 5, 6]);
+
+    batchingConnection.mutate([7, 8, 9]);
+
+    expect(connection.mutate).toHaveBeenCalledTimes(1);
+
+    await waitOneTick();
+
+    expect(connection.mutate).toHaveBeenCalledTimes(2);
+    expect(connection.mutate).toHaveBeenCalledWith([7, 8, 9]);
+  });
+
+  it('flushes mutations', async () => {
+    const connection = createRemoteConnectionSpy();
+    const batchingConnection = new BatchingRemoteConnection(connection);
+
+    batchingConnection.mutate([1, 2, 3]);
+    batchingConnection.flush();
+
+    expect(connection.mutate).toHaveBeenCalledOnce();
+    expect(connection.mutate).toHaveBeenCalledWith([1, 2, 3]);
+
+    await waitOneTick();
+
+    // ensure it wasn't called again
+    expect(connection.mutate).toHaveBeenCalledOnce();
+    batchingConnection.mutate([4, 5, 6]);
+
+    await waitOneTick();
+
+    expect(connection.mutate).toHaveBeenCalledTimes(2);
+    expect(connection.mutate).toHaveBeenCalledWith([4, 5, 6]);
+  });
+});
+
+async function waitOneTick() {
+  await new Promise((resolve) => setTimeout(resolve, 0));
+}
+
+function createRemoteConnectionSpy(): MockedObject<RemoteConnection> {
+  return {
+    mutate: vi.fn(),
+    call: vi.fn(),
+  };
+}