diff --git a/extensions/google/realtime-voice-provider.test.ts b/extensions/google/realtime-voice-provider.test.ts
index afb88a2fe5f..491f82252c7 100644
--- a/extensions/google/realtime-voice-provider.test.ts
+++ b/extensions/google/realtime-voice-provider.test.ts
@@ -65,6 +65,26 @@ function sentAudio(index = 0): { data?: unknown; mimeType?: unknown } {
   return audio as { data?: unknown; mimeType?: unknown };
 }
 
+function requireFirstMockArg(mock: ReturnType<typeof vi.fn>, label: string): unknown {
+  const [call] = mock.mock.calls;
+  if (!call) {
+    throw new Error(`expected ${label}`);
+  }
+  return call[0];
+}
+
+function requireFirstError(mock: ReturnType<typeof vi.fn>): { message?: string } {
+  const error = requireFirstMockArg(mock, "Google Live error");
+  if (!error || typeof error !== "object" || Array.isArray(error)) {
+    throw new Error("expected Google Live error");
+  }
+  return error as { message?: string };
+}
+
+function requireFirstAudio(mock: ReturnType<typeof vi.fn>): unknown {
+  return requireFirstMockArg(mock, "Google Live audio");
+}
+
 describe("buildGoogleRealtimeVoiceProvider", () => {
   beforeEach(() => {
     envSnapshot = Object.fromEntries(ENV_KEYS.map((key) => [key, process.env[key]]));
@@ -320,7 +340,7 @@ describe("buildGoogleRealtimeVoiceProvider", () => {
     });
 
     expect(createTokenMock).toHaveBeenCalledTimes(1);
-    const tokenConfig = createTokenMock.mock.calls[0]?.[0] as {
+    const tokenConfig = requireFirstMockArg(createTokenMock, "Google Live auth token config") as {
       config?: {
         liveConnectConstraints?: {
           config?: {
@@ -445,7 +465,7 @@ describe("buildGoogleRealtimeVoiceProvider", () => {
       });
 
       expect(onClose).not.toHaveBeenCalled();
-      const error = onError.mock.calls[0]?.[0] as { message?: string };
+      const error = requireFirstError(onError);
       expect(error.message).toContain("reconnecting 1/3");
 
       await vi.advanceTimersByTimeAsync(250);
@@ -627,8 +647,9 @@ describe("buildGoogleRealtimeVoiceProvider", () => {
     });
 
     expect(onAudio).toHaveBeenCalledTimes(1);
-    expect(onAudio.mock.calls[0]?.[0]).toBeInstanceOf(Buffer);
-    expect(onAudio.mock.calls[0]?.[0]).toHaveLength(80);
+    const audio = requireFirstAudio(onAudio);
+    expect(audio).toBeInstanceOf(Buffer);
+    expect(audio).toHaveLength(80);
   });
 
   it("can keep Google PCM output as PCM16 24 kHz audio", async () => {
@@ -660,7 +681,7 @@ describe("buildGoogleRealtimeVoiceProvider", () => {
     });
 
     expect(onAudio).toHaveBeenCalledTimes(1);
-    expect(onAudio.mock.calls[0]?.[0]).toEqual(pcm24k);
+    expect(requireFirstAudio(onAudio)).toEqual(pcm24k);
   });
 
   it("does not forward Google thought text as assistant transcript", async () => {
@@ -788,7 +809,7 @@ describe("buildGoogleRealtimeVoiceProvider", () => {
     bridge.submitToolResult("missing-call", { result: "ok" });
 
     expect(session.sendToolResponse).not.toHaveBeenCalled();
-    const error = onError.mock.calls[0]?.[0] as { message?: string };
+    const error = requireFirstError(onError);
     expect(error.message).toBe(
       "Google Live function response is missing a matching function call for missing-call",
     );