feat: Add "Compare with Friend" side-by-side GitHub stats view

src/__tests__/comparison.test.js

@@ -0,0 +1,113 @@
+import { describe, it, expect } from "vitest";
+
+const determineWinner = (aVal, bVal, lowerIsBetter) => {
+  if (aVal === bVal) return "tie";
+  if (lowerIsBetter) return aVal < bVal ? "left" : "right";
+  return aVal > bVal ? "left" : "right";
+};
+
+const getWinnerScore = (user) => {
+  return (user?.points?.gitRankPoints || 0) * 0.5 +
+         (user?.points?.totalPoints || 0) * 0.3 +
+         (user?.githubStats?.commits || 0) * 0.1 +
+         (user?.streak || 0) * 0.1;
+};
+
+const countUnlockedBadges = (user) => {
+  if (!user) return 0;
+  const gitRankPoints = user.points?.gitRankPoints || 0;
+  const streak = user.streak || 0;
+  const codingVersePoints = user.points?.codingVersePoints || 0;
+  const referralPoints = user.points?.referralPoints || 0;
+
+  let count = 1;
+  if (gitRankPoints >= 100) count++;
+  if (streak >= 10) count++;
+  if (codingVersePoints >= 100) count++;
+  if (referralPoints >= 1000) count++;
+  return count;
+};
+
+describe("Comparison Winner Logic", () => {
+  it("higher value wins when lowerIsBetter is false", () => {
+    expect(determineWinner(100, 50, false)).toBe("left");
+    expect(determineWinner(50, 100, false)).toBe("right");
+  });
+
+  it("lower value wins when lowerIsBetter is true", () => {
+    expect(determineWinner(5, 10, true)).toBe("left");
+    expect(determineWinner(10, 5, true)).toBe("right");
+  });
+
+  it("returns tie for equal values", () => {
+    expect(determineWinner(100, 100, false)).toBe("tie");
+    expect(determineWinner(5, 5, true)).toBe("tie");
+  });
+
+  it("calculates overall winner score correctly", () => {
+    const user = {
+      points: { gitRankPoints: 100, totalPoints: 200 },
+      githubStats: { commits: 50 },
+      streak: 10,
+    };
+    expect(getWinnerScore(user)).toBe(116);
+  });
+
+  it("handles missing data gracefully", () => {
+    expect(getWinnerScore({})).toBe(0);
+    expect(determineWinner(0, 0, false)).toBe("tie");
+  });
+});
+
+describe("Badge Counting", () => {
+  it("always counts Pioneer badge", () => {
+    expect(countUnlockedBadges({})).toBe(1);
+  });
+
+  it("counts all unlocked badges", () => {
+    const user = {
+      points: { gitRankPoints: 150, totalPoints: 500, codingVersePoints: 200, referralPoints: 2000 },
+      streak: 15,
+    };
+    expect(countUnlockedBadges(user)).toBe(5);
+  });
+
+  it("counts partial badges", () => {
+    const user = {
+      points: { gitRankPoints: 50, totalPoints: 100, codingVersePoints: 50, referralPoints: 500 },
+      streak: 5,
+    };
+    expect(countUnlockedBadges(user)).toBe(1);
+  });
+});
+
+describe("localStorage Persistence", () => {
+  beforeEach(() => {
+    localStorage.clear();
+  });
+
+  it("stores and retrieves recent comparisons", () => {
+    const STORAGE_KEY = "rankerhub_recent_comparisons";
+    const data = [
+      { username: "alice", name: "Alice", avatar: "https://example.com/a.png" },
+      { username: "bob", name: "Bob", avatar: "https://example.com/b.png" },
+    ];
+    localStorage.setItem(STORAGE_KEY, JSON.stringify(data));
+    const retrieved = JSON.parse(localStorage.getItem(STORAGE_KEY));
+    expect(retrieved).toHaveLength(2);
+    expect(retrieved[0].username).toBe("alice");
+  });
+
+  it("respects max 5 entries", () => {
+    const STORAGE_KEY = "rankerhub_recent_comparisons";
+    const data = Array.from({ length: 7 }, (_, i) => ({
+      username: `user${i}`,
+      name: `User ${i}`,
+      avatar: "",
+    }));
+    const trimmed = data.slice(0, 5);
+    localStorage.setItem(STORAGE_KEY, JSON.stringify(trimmed));
+    const retrieved = JSON.parse(localStorage.getItem(STORAGE_KEY));
+    expect(retrieved).toHaveLength(5);
+  });
+});