fix(cli): Add delimiter before printing tool response in non-interactive mode (#11351)

packages/cli/src/nonInteractiveCli.test.ts

@@ -190,6 +190,9 @@ describe('runNonInteractive', () => {
     }
   }
 
+  const getWrittenOutput = () =>
+    processStdoutSpy.mock.calls.map((c) => c[0]).join('');
+
   it('should process input and write text output', async () => {
     const events: ServerGeminiStreamEvent[] = [
       { type: GeminiEventType.Content, value: 'Hello' },
@@ -215,9 +218,7 @@ describe('runNonInteractive', () => {
       expect.any(AbortSignal),
       'prompt-id-1',
     );
-    expect(processStdoutSpy).toHaveBeenCalledWith('Hello');
-    expect(processStdoutSpy).toHaveBeenCalledWith(' World');
-    expect(processStdoutSpy).toHaveBeenCalledWith('\n');
+    expect(getWrittenOutput()).toBe('Hello World\n');
     expect(mockShutdownTelemetry).toHaveBeenCalled();
   });
 
@@ -285,8 +286,77 @@ describe('runNonInteractive', () => {
       expect.any(AbortSignal),
       'prompt-id-2',
     );
-    expect(processStdoutSpy).toHaveBeenCalledWith('Final answer');
-    expect(processStdoutSpy).toHaveBeenCalledWith('\n');
+    expect(getWrittenOutput()).toBe('Final answer\n');
+  });
+
+  it('should write a single newline between sequential text outputs from the model', async () => {
+    // This test simulates a multi-turn conversation to ensure that a single newline
+    // is printed between each block of text output from the model.
+
+    // 1. Define the tool requests that the model will ask the CLI to run.
+    const toolCallEvent: ServerGeminiStreamEvent = {
+      type: GeminiEventType.ToolCallRequest,
+      value: {
+        callId: 'mock-tool',
+        name: 'mockTool',
+        args: {},
+        isClientInitiated: false,
+        prompt_id: 'prompt-id-multi',
+      },
+    };
+
+    // 2. Mock the execution of the tools. We just need them to succeed.
+    mockCoreExecuteToolCall.mockResolvedValue({
+      status: 'success',
+      request: toolCallEvent.value, // This is generic enough for both calls
+      tool: {} as AnyDeclarativeTool,
+      invocation: {} as AnyToolInvocation,
+      response: {
+        responseParts: [],
+        callId: 'mock-tool',
+      },
+    });
+
+    // 3. Define the sequence of events streamed from the mock model.
+    // Turn 1: Model outputs text, then requests a tool call.
+    const modelTurn1: ServerGeminiStreamEvent[] = [
+      { type: GeminiEventType.Content, value: 'Use mock tool' },
+      toolCallEvent,
+    ];
+    // Turn 2: Model outputs more text, then requests another tool call.
+    const modelTurn2: ServerGeminiStreamEvent[] = [
+      { type: GeminiEventType.Content, value: 'Use mock tool again' },
+      toolCallEvent,
+    ];
+    // Turn 3: Model outputs a final answer.
+    const modelTurn3: ServerGeminiStreamEvent[] = [
+      { type: GeminiEventType.Content, value: 'Finished.' },
+      {
+        type: GeminiEventType.Finished,
+        value: { reason: undefined, usageMetadata: { totalTokenCount: 10 } },
+      },
+    ];
+
+    mockGeminiClient.sendMessageStream
+      .mockReturnValueOnce(createStreamFromEvents(modelTurn1))
+      .mockReturnValueOnce(createStreamFromEvents(modelTurn2))
+      .mockReturnValueOnce(createStreamFromEvents(modelTurn3));
+
+    // 4. Run the command.
+    await runNonInteractive(
+      mockConfig,
+      mockSettings,
+      'Use mock tool multiple times',
+      'prompt-id-multi',
+    );
+
+    // 5. Verify the output.
+    // The rendered output should contain the text from each turn, separated by a
+    // single newline, with a final newline at the end.
+    expect(getWrittenOutput()).toMatchSnapshot();
+
+    // Also verify the tools were called as expected.
+    expect(mockCoreExecuteToolCall).toHaveBeenCalledTimes(2);
   });
 
   it('should handle error during tool execution and should send error back to the model', async () => {
@@ -369,7 +439,7 @@ describe('runNonInteractive', () => {
       expect.any(AbortSignal),
       'prompt-id-3',
     );
-    expect(processStdoutSpy).toHaveBeenCalledWith('Sorry, let me try again.');
+    expect(getWrittenOutput()).toBe('Sorry, let me try again.\n');
   });
 
   it('should exit with error if sendMessageStream throws initially', async () => {
@@ -444,9 +514,7 @@ describe('runNonInteractive', () => {
       'Error executing tool nonexistentTool: Tool "nonexistentTool" not found in registry.',
     );
     expect(mockGeminiClient.sendMessageStream).toHaveBeenCalledTimes(2);
-    expect(processStdoutSpy).toHaveBeenCalledWith(
-      "Sorry, I can't find that tool.",
-    );
+    expect(getWrittenOutput()).toBe("Sorry, I can't find that tool.\n");
   });
 
   it('should exit when max session turns are exceeded', async () => {
@@ -506,7 +574,7 @@ describe('runNonInteractive', () => {
     );
 
     // 6. Assert the final output is correct
-    expect(processStdoutSpy).toHaveBeenCalledWith('Summary complete.');
+    expect(getWrittenOutput()).toBe('Summary complete.\n');
   });
 
   it('should process input and write JSON output with stats', async () => {
@@ -850,7 +918,7 @@ describe('runNonInteractive', () => {
       'prompt-id-slash',
     );
 
-    expect(processStdoutSpy).toHaveBeenCalledWith('Response from command');
+    expect(getWrittenOutput()).toBe('Response from command\n');
   });
 
   it('should throw FatalInputError if a command requires confirmation', async () => {
@@ -905,7 +973,7 @@ describe('runNonInteractive', () => {
       'prompt-id-unknown',
     );
 
-    expect(processStdoutSpy).toHaveBeenCalledWith('Response to unknown');
+    expect(getWrittenOutput()).toBe('Response to unknown\n');
   });
 
   it('should throw for unhandled command result types', async () => {
@@ -962,7 +1030,7 @@ describe('runNonInteractive', () => {
 
     expect(mockAction).toHaveBeenCalledWith(expect.any(Object), 'arg1 arg2');
 
-    expect(processStdoutSpy).toHaveBeenCalledWith('Acknowledged');
+    expect(getWrittenOutput()).toBe('Acknowledged\n');
   });
 
   it('should instantiate CommandService with correct loaders for slash commands', async () => {
@@ -1073,7 +1141,7 @@ describe('runNonInteractive', () => {
       expect.objectContaining({ name: 'ShellTool' }),
       expect.any(AbortSignal),
     );
-    expect(processStdoutSpy).toHaveBeenCalledWith('file.txt');
+    expect(getWrittenOutput()).toBe('file.txt\n');
   });
 
   describe('CoreEvents Integration', () => {