test: add comprehensive tests for export utilities

Add tests for exportToCSV, exportToJSON, and formatDateForExport
covering file download, date formatting, and edge cases.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

__tests__/utils/export.test.ts

@@ -0,0 +1,227 @@
+/**
+ * Tests for the export utility functions
+ * @jest-environment jsdom
+ */
+
+import { exportToCSV, exportToJSON, formatDateForExport } from '@/utils/export';
+
+describe('Export Utilities', () => {
+  // Mock DOM methods for file download
+  let mockClick: jest.Mock;
+  let mockLink: Partial<HTMLAnchorElement>;
+  const originalCreateObjectURL = URL.createObjectURL;
+  const originalRevokeObjectURL = URL.revokeObjectURL;
+
+  beforeAll(() => {
+    // Mock URL methods globally
+    URL.createObjectURL = jest.fn(() => 'blob:test-url');
+    URL.revokeObjectURL = jest.fn();
+  });
+
+  afterAll(() => {
+    URL.createObjectURL = originalCreateObjectURL;
+    URL.revokeObjectURL = originalRevokeObjectURL;
+  });
+
+  beforeEach(() => {
+    mockClick = jest.fn();
+    mockLink = {
+      href: '',
+      download: '',
+      style: { display: '' } as CSSStyleDeclaration,
+      click: mockClick,
+    };
+
+    jest.spyOn(document, 'createElement').mockReturnValue(mockLink as HTMLAnchorElement);
+    jest.spyOn(document.body, 'appendChild').mockImplementation(() => mockLink as Node);
+    jest.spyOn(document.body, 'removeChild').mockImplementation(() => mockLink as Node);
+  });
+
+  afterEach(() => {
+    jest.restoreAllMocks();
+  });
+
+  describe('exportToCSV', () => {
+    it('should create and download a CSV file', () => {
+      const data = [
+        ['Header1', 'Header2'],
+        ['Value1', 'Value2'],
+      ];
+
+      exportToCSV(data, 'test-file');
+
+      expect(document.createElement).toHaveBeenCalledWith('a');
+      expect(URL.createObjectURL).toHaveBeenCalled();
+      expect(document.body.appendChild).toHaveBeenCalled();
+      expect(mockClick).toHaveBeenCalled();
+      expect(document.body.removeChild).toHaveBeenCalled();
+      expect(URL.revokeObjectURL).toHaveBeenCalledWith('blob:test-url');
+    });
+
+    it('should include date in filename by default', () => {
+      const data = [['test']];
+      const today = new Date().toISOString().split('T')[0];
+
+      exportToCSV(data, 'test-file');
+
+      expect(mockLink.download).toContain('test-file');
+      expect(mockLink.download).toContain(today);
+      expect(mockLink.download).toContain('.csv');
+    });
+
+    it('should exclude date when includeDate is false', () => {
+      const data = [['test']];
+
+      exportToCSV(data, 'test-file', { includeDate: false });
+
+      expect(mockLink.download).toBe('test-file.csv');
+    });
+
+    it('should use custom separator', () => {
+      const data = [['A', 'B'], ['C', 'D']];
+
+      // We can't easily verify the content of the blob, but we can verify the function runs
+      expect(() => exportToCSV(data, 'test', { separator: ';' })).not.toThrow();
+      expect(mockClick).toHaveBeenCalled();
+    });
+
+    it('should handle null and undefined values', () => {
+      const data = [[null, undefined, 'value']];
+
+      expect(() => exportToCSV(data, 'test')).not.toThrow();
+      expect(mockClick).toHaveBeenCalled();
+    });
+
+    it('should escape values containing separator', () => {
+      const data = [['value,with,commas', 'normal']];
+
+      expect(() => exportToCSV(data, 'test')).not.toThrow();
+      expect(mockClick).toHaveBeenCalled();
+    });
+
+    it('should escape values containing quotes', () => {
+      const data = [['value"with"quotes', 'normal']];
+
+      expect(() => exportToCSV(data, 'test')).not.toThrow();
+      expect(mockClick).toHaveBeenCalled();
+    });
+
+    it('should escape values containing newlines', () => {
+      const data = [['value\nwith\nnewlines', 'normal']];
+
+      expect(() => exportToCSV(data, 'test')).not.toThrow();
+      expect(mockClick).toHaveBeenCalled();
+    });
+
+    it('should handle boolean values', () => {
+      const data = [[true, false]];
+
+      expect(() => exportToCSV(data, 'test')).not.toThrow();
+      expect(mockClick).toHaveBeenCalled();
+    });
+
+    it('should handle number values', () => {
+      const data = [[123, 456.78]];
+
+      expect(() => exportToCSV(data, 'test')).not.toThrow();
+      expect(mockClick).toHaveBeenCalled();
+    });
+
+    it('should set link style to hidden', () => {
+      const data = [['test']];
+
+      exportToCSV(data, 'test');
+
+      expect(mockLink.style?.display).toBe('none');
+    });
+  });
+
+  describe('exportToJSON', () => {
+    it('should create and download a JSON file', () => {
+      const data = { key: 'value', nested: { a: 1 } };
+
+      exportToJSON(data, 'test-file');
+
+      expect(document.createElement).toHaveBeenCalledWith('a');
+      expect(URL.createObjectURL).toHaveBeenCalled();
+      expect(document.body.appendChild).toHaveBeenCalled();
+      expect(mockClick).toHaveBeenCalled();
+      expect(document.body.removeChild).toHaveBeenCalled();
+      expect(URL.revokeObjectURL).toHaveBeenCalledWith('blob:test-url');
+    });
+
+    it('should include date in filename', () => {
+      const data = { test: true };
+      const today = new Date().toISOString().split('T')[0];
+
+      exportToJSON(data, 'test-file');
+
+      expect(mockLink.download).toContain('test-file');
+      expect(mockLink.download).toContain(today);
+      expect(mockLink.download).toContain('.json');
+    });
+
+    it('should handle arrays', () => {
+      const data = [1, 2, 3, { a: 'b' }];
+
+      expect(() => exportToJSON(data, 'test')).not.toThrow();
+      expect(mockClick).toHaveBeenCalled();
+    });
+
+    it('should handle nested objects', () => {
+      const data = {
+        level1: {
+          level2: {
+            level3: 'deep',
+          },
+        },
+      };
+
+      expect(() => exportToJSON(data, 'test')).not.toThrow();
+      expect(mockClick).toHaveBeenCalled();
+    });
+
+    it('should set link style to hidden', () => {
+      const data = { test: true };
+
+      exportToJSON(data, 'test');
+
+      expect(mockLink.style?.display).toBe('none');
+    });
+  });
+
+  describe('formatDateForExport', () => {
+    it('should format date string correctly', () => {
+      const result = formatDateForExport('2024-01-15T10:30:00Z');
+
+      // French format: DD/MM/YYYY HH:MM
+      expect(result).toMatch(/\d{2}\/\d{2}\/\d{4}/);
+    });
+
+    it('should format Date object correctly', () => {
+      const date = new Date('2024-01-15T10:30:00Z');
+      const result = formatDateForExport(date);
+
+      expect(result).toMatch(/\d{2}\/\d{2}\/\d{4}/);
+    });
+
+    it('should return empty string for null', () => {
+      expect(formatDateForExport(null)).toBe('');
+    });
+
+    it('should return empty string for undefined', () => {
+      expect(formatDateForExport(undefined)).toBe('');
+    });
+
+    it('should return empty string for empty string', () => {
+      expect(formatDateForExport('')).toBe('');
+    });
+
+    it('should include time in the format', () => {
+      const result = formatDateForExport('2024-01-15T10:30:00Z');
+
+      // Should contain time component
+      expect(result).toMatch(/\d{2}:\d{2}/);
+    });
+  });
+});