test(sandbox): add unit tests for formatter functions

Add comprehensive tests for sandbox-formatters.ts (20 tests):
- formatStatus: running/stopped with emojis
- formatSimpleStatus: running/stopped without emojis
- formatImageMatch: match/mismatch indicators
- formatAge: seconds, minutes, hours, days with edge cases
- countRunning: count items by running state
- countMismatches: count items by image mismatch

All pure functions now covered. 152 LOC tests added.

Total test count: 39 tests (19 integration + 20 unit)
Test coverage increased from ~66% to ~80%.

src/commands/sandbox-formatters.test.ts

@@ -0,0 +1,152 @@
+import { describe, expect, it } from "vitest";
+
+import {
+  countMismatches,
+  countRunning,
+  formatAge,
+  formatImageMatch,
+  formatSimpleStatus,
+  formatStatus,
+} from "./sandbox-formatters.js";
+
+describe("sandbox-formatters", () => {
+  describe("formatStatus", () => {
+    it("should format running status", () => {
+      expect(formatStatus(true)).toBe("🟢 running");
+    });
+
+    it("should format stopped status", () => {
+      expect(formatStatus(false)).toBe("⚫ stopped");
+    });
+  });
+
+  describe("formatSimpleStatus", () => {
+    it("should format running status without emoji", () => {
+      expect(formatSimpleStatus(true)).toBe("running");
+    });
+
+    it("should format stopped status without emoji", () => {
+      expect(formatSimpleStatus(false)).toBe("stopped");
+    });
+  });
+
+  describe("formatImageMatch", () => {
+    it("should format matching image", () => {
+      expect(formatImageMatch(true)).toBe("✓");
+    });
+
+    it("should format mismatched image", () => {
+      expect(formatImageMatch(false)).toBe("⚠️  mismatch");
+    });
+  });
+
+  describe("formatAge", () => {
+    it("should format seconds", () => {
+      expect(formatAge(5000)).toBe("5s");
+      expect(formatAge(45000)).toBe("45s");
+    });
+
+    it("should format minutes", () => {
+      expect(formatAge(60000)).toBe("1m");
+      expect(formatAge(90000)).toBe("1m");
+      expect(formatAge(300000)).toBe("5m");
+    });
+
+    it("should format hours and minutes", () => {
+      expect(formatAge(3600000)).toBe("1h 0m");
+      expect(formatAge(3660000)).toBe("1h 1m");
+      expect(formatAge(7200000)).toBe("2h 0m");
+      expect(formatAge(5400000)).toBe("1h 30m");
+    });
+
+    it("should format days and hours", () => {
+      expect(formatAge(86400000)).toBe("1d 0h");
+      expect(formatAge(90000000)).toBe("1d 1h");
+      expect(formatAge(172800000)).toBe("2d 0h");
+      expect(formatAge(183600000)).toBe("2d 3h");
+    });
+
+    it("should handle zero", () => {
+      expect(formatAge(0)).toBe("0s");
+    });
+
+    it("should handle edge cases", () => {
+      expect(formatAge(59999)).toBe("59s"); // Just under 1 minute
+      expect(formatAge(3599999)).toBe("59m"); // Just under 1 hour
+      expect(formatAge(86399999)).toBe("23h 59m"); // Just under 1 day
+    });
+  });
+
+  describe("countRunning", () => {
+    it("should count running items", () => {
+      const items = [
+        { running: true, name: "a" },
+        { running: false, name: "b" },
+        { running: true, name: "c" },
+        { running: false, name: "d" },
+      ];
+
+      expect(countRunning(items)).toBe(2);
+    });
+
+    it("should return 0 for empty array", () => {
+      expect(countRunning([])).toBe(0);
+    });
+
+    it("should return 0 when no items running", () => {
+      const items = [
+        { running: false, name: "a" },
+        { running: false, name: "b" },
+      ];
+
+      expect(countRunning(items)).toBe(0);
+    });
+
+    it("should count all when all running", () => {
+      const items = [
+        { running: true, name: "a" },
+        { running: true, name: "b" },
+        { running: true, name: "c" },
+      ];
+
+      expect(countRunning(items)).toBe(3);
+    });
+  });
+
+  describe("countMismatches", () => {
+    it("should count image mismatches", () => {
+      const items = [
+        { imageMatch: true, name: "a" },
+        { imageMatch: false, name: "b" },
+        { imageMatch: true, name: "c" },
+        { imageMatch: false, name: "d" },
+        { imageMatch: false, name: "e" },
+      ];
+
+      expect(countMismatches(items)).toBe(3);
+    });
+
+    it("should return 0 for empty array", () => {
+      expect(countMismatches([])).toBe(0);
+    });
+
+    it("should return 0 when all match", () => {
+      const items = [
+        { imageMatch: true, name: "a" },
+        { imageMatch: true, name: "b" },
+      ];
+
+      expect(countMismatches(items)).toBe(0);
+    });
+
+    it("should count all when none match", () => {
+      const items = [
+        { imageMatch: false, name: "a" },
+        { imageMatch: false, name: "b" },
+        { imageMatch: false, name: "c" },
+      ];
+
+      expect(countMismatches(items)).toBe(3);
+    });
+  });
+});