test(cli): add unit tests for /btw command functionality and components

packages/cli/src/ui/commands/btwCommand.test.ts

@@ -0,0 +1,38 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect } from 'vitest';
+import { btwCommand } from './btwCommand.js';
+import { CommandKind } from './types.js';
+import type { CommandContext } from './types.js';
+
+describe('btwCommand', () => {
+  it('has the correct metadata', () => {
+    expect(btwCommand.name).toBe('btw');
+    expect(btwCommand.kind).toBe(CommandKind.BUILT_IN);
+    expect(btwCommand.autoExecute).toBe(true);
+    expect(btwCommand.isSafeConcurrent).toBe(true);
+  });
+
+  it('returns an error message when args are empty', () => {
+    const context = {} as CommandContext;
+    const result = btwCommand.action!(context, '   ');
+    expect(result).toEqual({
+      type: 'message',
+      messageType: 'error',
+      content: 'Please provide a question, e.g. /btw what is this regex doing?',
+    });
+  });
+
+  it('returns a btw action when query is provided', () => {
+    const context = {} as CommandContext;
+    const result = btwCommand.action!(context, ' what is this regex doing? ');
+    expect(result).toEqual({
+      type: 'btw',
+      query: 'what is this regex doing?',
+    });
+  });
+});

packages/cli/src/ui/components/BtwDisplay.test.tsx

@@ -0,0 +1,88 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect } from 'vitest';
+import { renderWithProviders } from '../../test-utils/render.js';
+import { BtwDisplay } from './BtwDisplay.js';
+import { StreamingState } from '../types.js';
+import type { UIState } from '../contexts/UIStateContext.js';
+
+describe('BtwDisplay', () => {
+  const defaultMockUiState = {
+    renderMarkdown: true,
+  } as unknown as Partial<UIState>;
+
+  it('renders nothing when query is empty', async () => {
+    const { lastFrame, unmount } = await renderWithProviders(
+      <BtwDisplay
+        query=""
+        response=""
+        isStreaming={false}
+        error={null}
+        terminalWidth={100}
+      />,
+      { uiState: defaultMockUiState },
+    );
+    expect(lastFrame({ allowEmpty: true })).toBe('');
+    unmount();
+  });
+
+  it('renders query and response', async () => {
+    const { lastFrame, unmount } = await renderWithProviders(
+      <BtwDisplay
+        query="What is life?"
+        response="Life is 42."
+        isStreaming={false}
+        error={null}
+        terminalWidth={100}
+      />,
+      { uiState: defaultMockUiState },
+    );
+    const frame = lastFrame();
+    expect(frame).toContain('What is life?');
+    expect(frame).toContain('Life is 42.');
+    expect(frame).toContain('BY THE WAY');
+    unmount();
+  });
+
+  it('renders error message when error is provided', async () => {
+    const { lastFrame, unmount } = await renderWithProviders(
+      <BtwDisplay
+        query="What is life?"
+        response="Life is 42."
+        isStreaming={false}
+        error="An API error occurred."
+        terminalWidth={100}
+      />,
+      { uiState: defaultMockUiState },
+    );
+    const frame = lastFrame();
+    expect(frame).toContain('An API error occurred.');
+    expect(frame).not.toContain('Life is 42.');
+    unmount();
+  });
+
+  it('renders a spinner when streaming', async () => {
+    const { lastFrame, unmount } = await renderWithProviders(
+      <BtwDisplay
+        query="What is life?"
+        response="Life is 42."
+        isStreaming={true}
+        error={null}
+        terminalWidth={100}
+      />,
+      {
+        uiState: {
+          ...defaultMockUiState,
+          streamingState: StreamingState.Responding,
+        },
+      },
+    );
+    const frame = lastFrame();
+    expect(frame).toContain('⠋'); // Assuming standard spinner frame
+    unmount();
+  });
+});

packages/cli/src/ui/components/InputPrompt.test.tsx

@@ -5097,6 +5097,92 @@ describe('InputPrompt', () => {
       },
     );
   });
+
+  describe('Btw dismiss behavior', () => {
+    it('dismisses Btw on ESC key press', async () => {
+      const dismissBtw = vi.fn();
+      const { stdin, unmount } = await renderWithProviders(
+        <InputPrompt {...props} />,
+        {
+          uiState: {
+            btwState: {
+              isActive: true,
+              query: '',
+              response: '',
+              isStreaming: false,
+              error: null,
+            },
+          },
+          uiActions: { dismissBtw },
+        },
+      );
+
+      await act(async () => {
+        stdin.write('\x1B'); // ESC
+      });
+
+      await waitFor(() => {
+        expect(dismissBtw).toHaveBeenCalled();
+      });
+      unmount();
+    });
+
+    it('dismisses Btw on Enter key press', async () => {
+      const dismissBtw = vi.fn();
+      const { stdin, unmount } = await renderWithProviders(
+        <InputPrompt {...props} />,
+        {
+          uiState: {
+            btwState: {
+              isActive: true,
+              query: '',
+              response: '',
+              isStreaming: false,
+              error: null,
+            },
+          },
+          uiActions: { dismissBtw },
+        },
+      );
+
+      await act(async () => {
+        stdin.write('\r'); // Enter
+      });
+
+      await waitFor(() => {
+        expect(dismissBtw).toHaveBeenCalled();
+      });
+      unmount();
+    });
+
+    it('dismisses Btw on Space key press when buffer is empty', async () => {
+      const dismissBtw = vi.fn();
+      const { stdin, unmount } = await renderWithProviders(
+        <InputPrompt {...props} />,
+        {
+          uiState: {
+            btwState: {
+              isActive: true,
+              query: '',
+              response: '',
+              isStreaming: false,
+              error: null,
+            },
+          },
+          uiActions: { dismissBtw },
+        },
+      );
+
+      await act(async () => {
+        stdin.write(' '); // Space
+      });
+
+      await waitFor(() => {
+        expect(dismissBtw).toHaveBeenCalled();
+      });
+      unmount();
+    });
+  });
 });
 
 function clean(str: string | undefined): string {

packages/cli/src/ui/hooks/slashCommandProcessor.test.tsx

@@ -644,6 +644,31 @@ describe('useSlashCommandProcessor', () => {
 
       expect(mockSetQuittingMessages).toHaveBeenCalledWith(['bye']);
     });
+
+    it('should handle a "btw" action', async () => {
+      const btwAction = vi
+        .fn()
+        .mockResolvedValue({ type: 'btw', query: 'some query' });
+      const command = createTestCommand({
+        name: 'side_question',
+        action: btwAction,
+      });
+      const result = await setupProcessorHook({
+        builtinCommands: [command],
+      });
+
+      await waitFor(() => expect(result.current.slashCommands).toHaveLength(1));
+
+      let processedResult;
+      await act(async () => {
+        processedResult = await result.current.handleSlashCommand(
+          '/side_question some args',
+        );
+      });
+
+      expect(processedResult).toEqual({ type: 'btw', query: 'some query' });
+    });
+
     it('should handle "submit_prompt" action returned from a file-based command', async () => {
       const fileCommand = createTestCommand(
         {