Improve test coverage for cli/src/ui/components (#13598)

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

@@ -0,0 +1,54 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { render } from '../../test-utils/render.js';
+import { ShowMoreLines } from './ShowMoreLines.js';
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { useOverflowState } from '../contexts/OverflowContext.js';
+import { useStreamingContext } from '../contexts/StreamingContext.js';
+import { StreamingState } from '../types.js';
+
+vi.mock('../contexts/OverflowContext.js');
+vi.mock('../contexts/StreamingContext.js');
+
+describe('ShowMoreLines', () => {
+  const mockUseOverflowState = vi.mocked(useOverflowState);
+  const mockUseStreamingContext = vi.mocked(useStreamingContext);
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it.each([
+    [new Set(), StreamingState.Idle, true], // No overflow
+    [new Set(['1']), StreamingState.Idle, false], // Not constraining height
+    [new Set(['1']), StreamingState.Responding, true], // Streaming
+  ])(
+    'renders nothing when: overflow=%s, streaming=%s, constrain=%s',
+    (overflowingIds, streamingState, constrainHeight) => {
+      mockUseOverflowState.mockReturnValue({ overflowingIds } as NonNullable<
+        ReturnType<typeof useOverflowState>
+      >);
+      mockUseStreamingContext.mockReturnValue(streamingState);
+      const { lastFrame } = render(
+        <ShowMoreLines constrainHeight={constrainHeight} />,
+      );
+      expect(lastFrame()).toBe('');
+    },
+  );
+
+  it.each([[StreamingState.Idle], [StreamingState.WaitingForConfirmation]])(
+    'renders message when overflowing and state is %s',
+    (streamingState) => {
+      mockUseOverflowState.mockReturnValue({
+        overflowingIds: new Set(['1']),
+      } as NonNullable<ReturnType<typeof useOverflowState>>);
+      mockUseStreamingContext.mockReturnValue(streamingState);
+      const { lastFrame } = render(<ShowMoreLines constrainHeight={true} />);
+      expect(lastFrame()).toContain('Press ctrl-s to show more lines');
+    },
+  );
+});