test: Add comprehensive test coverage for Reports components (#223)

* test: add comprehensive test coverage for Reports components

- Add ReportsView.test.tsx with 18 tests covering data calculation, date filtering, and edge cases
- Add ReportChart.test.tsx with 18 tests for rendering, chart elements, and export functionality
- Add report-download-utils.test.ts with 11 tests for CSV/PNG export utilities
- Achieve 100% coverage on ReportsView, ReportChart, and report-download-utils
- Improve tasks-utils coverage from 39.56% to 94.5%
- Increase overall Tasks directory coverage from 41.85% to 61.05%
- All 214 tests passing with no regressions

* test: remove duplicate test in ReportChart.test.tsx

Remove duplicate 're-enables button after export completes' test case

Author: Rustix69

frontend/src/components/HomeComponents/Tasks/__tests__/ReportChart.test.tsx

@@ -0,0 +1,209 @@
+import { render, screen, fireEvent, waitFor } from '@testing-library/react';
+import { ReportChart } from '../ReportChart';
+import * as downloadUtils from '../report-download-utils';
+
+jest.mock('recharts', () => ({
+  ResponsiveContainer: ({ children }: any) => (
+    <div data-testid="responsive-container">{children}</div>
+  ),
+  BarChart: ({ children, data }: any) => (
+    <div data-testid="bar-chart" data-chart-data={JSON.stringify(data)}>
+      {children}
+    </div>
+  ),
+  Bar: ({ dataKey, fill, name }: any) => (
+    <div data-testid={`bar-${dataKey}`} data-fill={fill} data-name={name} />
+  ),
+  XAxis: ({ dataKey }: any) => <div data-testid="x-axis" data-key={dataKey} />,
+  YAxis: () => <div data-testid="y-axis" />,
+  Tooltip: () => <div data-testid="tooltip" />,
+  Legend: () => <div data-testid="legend" />,
+  CartesianGrid: () => <div data-testid="cartesian-grid" />,
+}));
+
+jest.mock('../report-download-utils', () => ({
+  exportReportToCSV: jest.fn(),
+  exportChartToPNG: jest.fn().mockResolvedValue(undefined),
+}));
+
+describe('ReportChart', () => {
+  const mockData = [{ name: 'Today', completed: 5, ongoing: 3 }];
+
+  const defaultProps = {
+    data: mockData,
+    title: 'Daily Report',
+    chartId: 'daily-report-chart',
+  };
+
+  beforeEach(() => {
+    jest.clearAllMocks();
+  });
+
+  describe('Rendering', () => {
+    it('renders chart with title', () => {
+      render(<ReportChart {...defaultProps} />);
+      expect(screen.getByText('Daily Report')).toBeInTheDocument();
+    });
+
+    it('renders CSV export button', () => {
+      render(<ReportChart {...defaultProps} />);
+      const csvButton = screen.getByTitle('Download as CSV');
+      expect(csvButton).toBeInTheDocument();
+    });
+
+    it('renders PNG export button', () => {
+      render(<ReportChart {...defaultProps} />);
+      const pngButton = screen.getByTitle('Download as PNG');
+      expect(pngButton).toBeInTheDocument();
+    });
+
+    it('renders bar chart with data', () => {
+      render(<ReportChart {...defaultProps} />);
+      const barChart = screen.getByTestId('bar-chart');
+      expect(barChart).toBeInTheDocument();
+      expect(barChart.getAttribute('data-chart-data')).toBe(
+        JSON.stringify(mockData)
+      );
+    });
+
+    it('renders responsive container', () => {
+      render(<ReportChart {...defaultProps} />);
+      expect(screen.getByTestId('responsive-container')).toBeInTheDocument();
+    });
+  });
+
+  describe('Chart Elements', () => {
+    it('displays completed bar with correct color', () => {
+      render(<ReportChart {...defaultProps} />);
+      const completedBar = screen.getByTestId('bar-completed');
+      expect(completedBar).toHaveAttribute('data-fill', '#E776CB');
+      expect(completedBar).toHaveAttribute('data-name', 'Completed');
+    });
+
+    it('displays ongoing bar with correct color', () => {
+      render(<ReportChart {...defaultProps} />);
+      const ongoingBar = screen.getByTestId('bar-ongoing');
+      expect(ongoingBar).toHaveAttribute('data-fill', '#5FD9FA');
+      expect(ongoingBar).toHaveAttribute('data-name', 'Ongoing');
+    });
+
+    it('renders chart axes', () => {
+      render(<ReportChart {...defaultProps} />);
+      expect(screen.getByTestId('x-axis')).toBeInTheDocument();
+      expect(screen.getByTestId('y-axis')).toBeInTheDocument();
+    });
+
+    it('renders legend', () => {
+      render(<ReportChart {...defaultProps} />);
+      expect(screen.getByTestId('legend')).toBeInTheDocument();
+    });
+
+    it('renders tooltip', () => {
+      render(<ReportChart {...defaultProps} />);
+      expect(screen.getByTestId('tooltip')).toBeInTheDocument();
+    });
+
+    it('renders cartesian grid', () => {
+      render(<ReportChart {...defaultProps} />);
+      expect(screen.getByTestId('cartesian-grid')).toBeInTheDocument();
+    });
+  });
+
+  describe('CSV Export', () => {
+    it('triggers CSV export when button clicked', () => {
+      render(<ReportChart {...defaultProps} />);
+      const csvButton = screen.getByTitle('Download as CSV');
+
+      fireEvent.click(csvButton);
+
+      expect(downloadUtils.exportReportToCSV).toHaveBeenCalledWith(
+        mockData,
+        'Daily Report'
+      );
+    });
+
+    it('does not disable CSV button during PNG export', async () => {
+      (downloadUtils.exportChartToPNG as jest.Mock).mockImplementation(
+        () => new Promise((resolve) => setTimeout(resolve, 100))
+      );
+
+      render(<ReportChart {...defaultProps} />);
+      const pngButton = screen.getByTitle('Download as PNG');
+      const csvButton = screen.getByTitle('Download as CSV');
+
+      fireEvent.click(pngButton);
+
+      expect(csvButton).toBeDisabled();
+    });
+  });
+
+  describe('PNG Export', () => {
+    it('triggers PNG export when button clicked', async () => {
+      render(<ReportChart {...defaultProps} />);
+      const pngButton = screen.getByTitle('Download as PNG');
+
+      fireEvent.click(pngButton);
+
+      await waitFor(() => {
+        expect(downloadUtils.exportChartToPNG).toHaveBeenCalledWith(
+          'daily-report-chart',
+          'Daily Report'
+        );
+      });
+    });
+
+    it('shows loading spinner during export', async () => {
+      (downloadUtils.exportChartToPNG as jest.Mock).mockImplementation(
+        () => new Promise((resolve) => setTimeout(resolve, 100))
+      );
+
+      render(<ReportChart {...defaultProps} />);
+      const pngButton = screen.getByTitle('Download as PNG');
+
+      fireEvent.click(pngButton);
+
+      expect(pngButton).toBeDisabled();
+
+      await waitFor(() => {
+        expect(downloadUtils.exportChartToPNG).toHaveBeenCalled();
+      });
+    });
+
+    it('re-enables button after export completes', async () => {
+      render(<ReportChart {...defaultProps} />);
+      const pngButton = screen.getByTitle('Download as PNG');
+
+      fireEvent.click(pngButton);
+
+      await waitFor(() => {
+        expect(pngButton).not.toBeDisabled();
+      });
+    });
+  });
+
+  describe('Multiple Data Points', () => {
+    it('handles multiple data entries', () => {
+      const multiData = [
+        { name: 'Week 1', completed: 10, ongoing: 5 },
+        { name: 'Week 2', completed: 8, ongoing: 7 },
+        { name: 'Week 3', completed: 12, ongoing: 3 },
+      ];
+
+      render(<ReportChart {...defaultProps} data={multiData} />);
+
+      const barChart = screen.getByTestId('bar-chart');
+      expect(barChart.getAttribute('data-chart-data')).toBe(
+        JSON.stringify(multiData)
+      );
+    });
+
+    it('handles zero values', () => {
+      const zeroData = [{ name: 'Today', completed: 0, ongoing: 0 }];
+
+      render(<ReportChart {...defaultProps} data={zeroData} />);
+
+      const barChart = screen.getByTestId('bar-chart');
+      expect(barChart).toBeInTheDocument();
+    });
+  });
+});