Change fetch implementation passing

frontend/test-client/src/agent/mock-agent.ts

@@ -25,14 +25,9 @@ export class MockAgent extends MockClient {
 	}
 
 	public async init(): Promise<void> {
-		await super.init();
+		await super.init(
-
+			// flaky fetch implementation to use during testing
-		assert(
+			async (
-			(await this.client.checkConnection()).isSuccessful,
-			"Connection check failed"
-		);
-
-		this.client.fetchImplementation = async (
 				input: string | URL | globalThis.Request,
 				init?: RequestInit
 			): Promise<Response> => {
@@ -40,7 +35,13 @@ export class MockAgent extends MockClient {
 				const response = await fetch(input, init);
 				await sleep(Math.random() * this.jitterScaleInSeconds * 1000);
 				return response;
-		};
+			}
+		);
+
+		assert(
+			(await this.client.checkConnection()).isSuccessful,
+			"Connection check failed"
+		);
 
 		this.client.logger.addOnMessageListener((logLine: LogLine) => {
 			const state = this.client.getSettings().isSyncEnabled

frontend/test-client/src/agent/mock-client.ts

@@ -16,11 +16,17 @@ export class MockClient implements FileSystemOperations {
 		protected readonly useSlowFileEvents: boolean
 	) {}
 
-	public async init(): Promise<void> {
+	public async init(
-		this.client = await SyncClient.create(this, {
+		fetchImplementation: typeof globalThis.fetch
+	): Promise<void> {
+		this.client = await SyncClient.create(
+			this,
+			{
 				load: async () => this.data,
 				save: async (data) => void (this.data = data)
-		});
+			},
+			fetchImplementation
+		);
 
 		await Promise.all(
 			Object.keys(this.initialSettings).map(async (key) => {