test: add tests for FocusContext

Introduce comprehensive test cases for FocusContext including focus setting, clearing, and context usage. Ensure correct behavior of focus manipulation and expected errors when used outside FocusProvider.

tests/context/FocusContext.test.tsx

@@ -0,0 +1,65 @@
+import React, { useRef } from 'react';
+import { render, fireEvent, screen } from '@testing-library/react';
+import '@testing-library/jest-dom';
+
+import { FocusProvider, useFocusContext } from '@/context/FocusContext';
+
+const TestComponent: React.FC = () => {
+    const { focusedElement, setFocusedElement, focusElement } = useFocusContext();
+    const inputRef1 = useRef<HTMLInputElement>(null);
+    const inputRef2 = useRef<HTMLInputElement>(null);
+
+    return (
+        <div>
+            <input ref={inputRef1} data-testid="test-input-1" />
+            <input ref={inputRef2} data-testid="test-input-2" />
+            <button onClick={() => focusElement(inputRef1.current!)}>Focus Input 1</button>
+            <button onClick={() => focusElement(inputRef2.current!)}>Focus Input 2</button>
+            <button onClick={() => setFocusedElement(null)}>Clear Focus</button>
+            <span data-testid="focused-element">{focusedElement ? focusedElement.tagName : 'None'}</span>
+        </div>
+    );
+};
+
+describe('FocusContext', () => {
+    it('provides context values to children', () => {
+        render(
+            <FocusProvider>
+                <TestComponent />
+            </FocusProvider>,
+        );
+
+        const input1 = screen.getByTestId('test-input-1') as HTMLInputElement;
+        const input2 = screen.getByTestId('test-input-2') as HTMLInputElement;
+        const focusButton1 = screen.getByText('Focus Input 1');
+        const focusButton2 = screen.getByText('Focus Input 2');
+        const focusedElementDisplay = screen.getByTestId('focused-element');
+
+        expect(focusedElementDisplay).toHaveTextContent('None');
+
+        fireEvent.click(focusButton1);
+        expect(document.activeElement).toBe(input1);
+        expect(focusedElementDisplay).toHaveTextContent('INPUT');
+
+        const blurSpy = jest.spyOn(input1, 'blur');
+
+        fireEvent.click(focusButton2);
+        expect(document.activeElement).toBe(input2);
+        expect(focusedElementDisplay).toHaveTextContent('INPUT');
+        expect(blurSpy).toHaveBeenCalled();
+
+        fireEvent.click(screen.getByText('Clear Focus'));
+        expect(focusedElementDisplay).toHaveTextContent('None');
+    });
+
+    it('throws an error if useFocusContext is used outside of FocusProvider', () => {
+        const renderWithoutProvider = () =>
+            render(
+                <div>
+                    <TestComponent />
+                </div>,
+            );
+
+        expect(renderWithoutProvider).toThrow('useFocusContext must be used within a FocusProvider');
+    });
+});