[FSSDK-12295] client hook update

Author: junaed-optimizely

src/hooks/index.ts

@@ -14,4 +14,5 @@
  * limitations under the License.
  */
 
+export { useOptimizelyClient } from './useOptimizelyClient';
 export { useOptimizelyUserContext } from './useOptimizelyUserContext';

src/hooks/useOptimizelyClient.spec.tsx

@@ -0,0 +1,93 @@
+/**
+ * Copyright 2026, Optimizely
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { vi, describe, it, expect } from 'vitest';
+import React, { useRef } from 'react';
+import { render, screen, act } from '@testing-library/react';
+import { renderHook } from '@testing-library/react';
+import { useOptimizelyClient } from './useOptimizelyClient';
+import { OptimizelyProvider, ProviderStateStore, OptimizelyContext } from '../provider/index';
+import { createInstance, createStaticProjectConfigManager } from '../client/index';
+import type { OptimizelyContextValue } from '../provider/index';
+
+function createClient() {
+  return createInstance({
+    projectConfigManager: createStaticProjectConfigManager({ datafile: JSON.stringify({}) }),
+  });
+}
+
+function useRenderCount() {
+  const renderCount = useRef(0);
+  return ++renderCount.current;
+}
+
+describe('useOptimizelyClient', () => {
+  it('should throw when used outside of OptimizelyProvider', () => {
+    const consoleSpy = vi.spyOn(console, 'error').mockImplementation(() => {});
+
+    expect(() => {
+      renderHook(() => useOptimizelyClient());
+    }).toThrow('useOptimizelyClient must be used within an <OptimizelyProvider>');
+
+    consoleSpy.mockRestore();
+  });
+
+  it('should return the same client instance passed to OptimizelyProvider', () => {
+    const client = createClient();
+
+    const { result } = renderHook(() => useOptimizelyClient(), {
+      wrapper: ({ children }) => <OptimizelyProvider client={client}>{children}</OptimizelyProvider>,
+    });
+
+    expect(result.current).toBe(client);
+  });
+
+  it('should not re-render when store state changes', () => {
+    const client = createClient();
+    const store = new ProviderStateStore();
+
+    const contextValue: OptimizelyContextValue = { store, client };
+
+    let capturedRenderCount = 0;
+
+    function TestComponent() {
+      const hookClient = useOptimizelyClient();
+      const renderCount = useRenderCount();
+      capturedRenderCount = renderCount;
+      return <div data-testid="client">{hookClient ? 'has-client' : 'no-client'}</div>;
+    }
+
+    render(
+      <OptimizelyContext.Provider value={contextValue}>
+        <TestComponent />
+      </OptimizelyContext.Provider>
+    );
+
+    expect(screen.getByTestId('client').textContent).toBe('has-client');
+    const initialRenderCount = capturedRenderCount;
+
+    // Trigger store state changes that should NOT cause useOptimizelyClient to re-render
+    act(() => {
+      store.setClientReady(true);
+    });
+    expect(capturedRenderCount).toBe(initialRenderCount);
+
+    act(() => {
+      store.setError(new Error('test'));
+    });
+    expect(capturedRenderCount).toBe(initialRenderCount);
+  });
+});

src/hooks/useOptimizelyClient.ts

@@ -0,0 +1,32 @@
+/**
+ * Copyright 2026, Optimizely
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { useContext } from 'react';
+import { OptimizelyContext } from '../provider/index';
+import type { Client } from '@optimizely/optimizely-sdk';
+
+/**
+ * Returns the Optimizely client instance from the nearest `<OptimizelyProvider>`.
+ */
+export function useOptimizelyClient(): Client {
+  const context = useContext(OptimizelyContext);
+
+  if (!context) {
+    throw new Error('useOptimizelyClient must be used within an <OptimizelyProvider>');
+  }
+
+  return context.client;
+}