Initial impl of config state hydration

Author: Kevin Elko

packages/remote-config/src/api.ts

@@ -21,7 +21,7 @@ import {
   RemoteConfig,
   Value
 } from './public_types';
-import { RemoteConfigAbortSignal } from './client/remote_config_fetch_client';
+import { RemoteConfigAbortSignal, FetchResponse } from './client/remote_config_fetch_client';
 import { RC_COMPONENT_NAME } from './constants';
 import { ErrorCode, hasErrorCode } from './errors';
 import { RemoteConfig as RemoteConfigImpl } from './remote_config';
@@ -131,6 +131,23 @@ export async function fetchConfig(remoteConfig: RemoteConfig): Promise<void> {
   }
 }
 
+/**
+ * Manually hydrates the config state without making an async fetch request.
+ * @param remoteConfig - The {@link RemoteConfig} instance.
+ * @param fetchResponse - The fetchResponse containing the config values and eTag
+ *    with which to hydrate the internal state.
+ */
+export async function setRenderedConfig(remoteConfig: RemoteConfig, fetchResponse: FetchResponse) {
+  const rc = getModularInstance(remoteConfig) as RemoteConfigImpl;
+  await Promise.all([
+    rc._storage.setLastSuccessfulFetchResponse(fetchResponse),
+    rc._storage.setActiveConfigEtag(fetchResponse.eTag || ''),
+    rc._storageCache.setLastSuccessfulFetchTimestampMillis(Date.now()),
+    rc._storageCache.setLastFetchStatus('success'),
+    rc._storageCache.setActiveConfig(fetchResponse.config || {}),
+  ]);
+}
+
 /**
  * Gets all config.
  *

packages/remote-config/src/client/remote_config_fetch_client.ts

@@ -107,6 +107,7 @@ export interface FetchRequest {
  * <p>Modeled after the native {@link Response} interface, but simplified for Remote Config's
  * use case.
  */
+// TODO - should we move this public_types.ts?
 export interface FetchResponse {
   /**
    * The HTTP status, which is useful for differentiating success responses with data from