add tests

apps/website/lib/display-objects/HealthMetricDisplay.ts

@@ -0,0 +1,61 @@
+/**
+ * Health Metric Display Object
+ *
+ * Provides formatting and display logic for health metrics.
+ * This display object isolates UI-specific formatting from business logic.
+ */
+
+export class HealthMetricDisplay {
+  static formatUptime(uptime?: number): string {
+    if (uptime === undefined || uptime === null) return 'N/A';
+    if (uptime < 0) return 'N/A';
+    
+    // Format as percentage with 2 decimal places
+    return `${uptime.toFixed(2)}%`;
+  }
+
+  static formatResponseTime(responseTime?: number): string {
+    if (responseTime === undefined || responseTime === null) return 'N/A';
+    if (responseTime < 0) return 'N/A';
+    
+    // Format as milliseconds with appropriate units
+    if (responseTime < 1000) {
+      return `${responseTime.toFixed(0)}ms`;
+    } else if (responseTime < 60000) {
+      return `${(responseTime / 1000).toFixed(2)}s`;
+    } else {
+      return `${(responseTime / 60000).toFixed(2)}m`;
+    }
+  }
+
+  static formatErrorRate(errorRate?: number): string {
+    if (errorRate === undefined || errorRate === null) return 'N/A';
+    if (errorRate < 0) return 'N/A';
+    
+    // Format as percentage with 2 decimal places
+    return `${errorRate.toFixed(2)}%`;
+  }
+
+  static formatTimestamp(timestamp: string): string {
+    const date = new Date(timestamp);
+    return date.toLocaleString('en-US', {
+      year: 'numeric',
+      month: 'short',
+      day: 'numeric',
+      hour: '2-digit',
+      minute: '2-digit',
+      second: '2-digit',
+    });
+  }
+
+  static formatSuccessRate(checksPassed?: number, checksFailed?: number): string {
+    const passed = checksPassed || 0;
+    const failed = checksFailed || 0;
+    const total = passed + failed;
+    
+    if (total === 0) return 'N/A';
+    
+    const successRate = (passed / total) * 100;
+    return `${successRate.toFixed(1)}%`;
+  }
+}