test(tracker-web): add unit tests for src/lib/utils.ts

- Add comprehensive tests for cn utility function
- Cover empty input, single/multiple classes, conflicting Tailwind classes
- Test conditional classes, arrays, objects, and complex mixed inputs
- 10 assertions total, exceeding minimum requirement of 4

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

dashboards/tracker-web/src/__tests__/utils.test.ts

@@ -0,0 +1,52 @@
+/**
+ * Tests for src/lib/utils.ts utility functions
+ */
+
+import { describe, it, expect } from 'vitest';
+import { cn } from '@/lib/utils';
+
+describe('cn utility function', () => {
+  it('should handle empty input', () => {
+    expect(cn()).toBe('');
+  });
+
+  it('should handle single class string', () => {
+    expect(cn('px-4')).toBe('px-4');
+  });
+
+  it('should handle multiple class strings', () => {
+    expect(cn('px-4', 'py-2', 'bg-blue-500')).toBe('px-4 py-2 bg-blue-500');
+  });
+
+  it('should merge conflicting Tailwind classes (last one wins)', () => {
+    expect(cn('px-4', 'px-2')).toBe('px-2');
+    expect(cn('bg-red-500', 'bg-blue-500')).toBe('bg-blue-500');
+  });
+
+  it('should handle conditional classes with null/undefined', () => {
+    expect(cn('px-4', null, 'py-2', undefined)).toBe('px-4 py-2');
+  });
+
+  it('should handle arrays of classes', () => {
+    expect(cn(['px-4', 'py-2'])).toBe('px-4 py-2');
+  });
+
+  it('should handle objects with boolean values', () => {
+    expect(cn({ 'px-4': true, 'py-2': false, 'bg-blue-500': true })).toBe('px-4 bg-blue-500');
+  });
+
+  it('should handle complex mixed inputs', () => {
+    expect(
+      cn('base-class', ['array-class'], { 'conditional-class': true, 'removed-class': false }, null)
+    ).toBe('base-class array-class conditional-class');
+  });
+
+  it('should handle empty arrays and objects', () => {
+    expect(cn([])).toBe('');
+    expect(cn({})).toBe('');
+  });
+
+  it('should handle conflicting classes in complex scenarios', () => {
+    expect(cn('text-sm', ['text-lg'], { 'text-xl': false })).toBe('text-lg');
+  });
+});