test : added unit tests for calculateCurrentStreak in leaderboard

test/leaderboard-streak.test.ts

@@ -0,0 +1,113 @@
+import { describe, it, expect } from 'vitest';
+
+function dateDiffDays(a: string, b: string): number {
+  return (new Date(b).getTime() - new Date(a).getTime()) / 86400000;
+}
+
+function toDateStr(date: Date): string {
+  return date.toISOString().slice(0, 10);
+}
+
+function calculateCurrentStreak(commitDates: string[]): number {
+  const days = Array.from(new Set(commitDates.map((date) => date.slice(0, 10)))).sort();
+  if (days.length === 0) {
+    return 0;
+  }
+
+  let runLength = 1;
+  const runs: { end: string; length: number }[] = [];
+  for (let i = 1; i < days.length; i += 1) {
+    if (dateDiffDays(days[i - 1], days[i]) === 1) {
+      runLength += 1;
+    } else {
+      runs.push({ end: days[i - 1], length: runLength });
+      runLength = 1;
+    }
+  }
+  runs.push({ end: days[days.length - 1], length: runLength });
+
+  const today = toDateStr(new Date());
+  const yesterday = toDateStr(new Date(Date.now() - 86400000));
+  const latest = runs[runs.length - 1];
+  return latest.end === today || latest.end === yesterday ? latest.length : 0;
+}
+
+describe('calculateCurrentStreak', () => {
+  it('returns 0 for empty dates array', () => {
+    expect(calculateCurrentStreak([])).toBe(0);
+  });
+
+  it('returns 1 for single contribution today', () => {
+    const today = toDateStr(new Date());
+    expect(calculateCurrentStreak([today])).toBe(1);
+  });
+
+  it('returns 1 for single contribution yesterday', () => {
+    const yesterday = toDateStr(new Date(Date.now() - 86400000));
+    expect(calculateCurrentStreak([yesterday])).toBe(1);
+  });
+
+  it('returns 0 if last contribution is before yesterday', () => {
+    const twoDaysAgo = toDateStr(new Date(Date.now() - 2 * 86400000));
+    const threeDaysAgo = toDateStr(new Date(Date.now() - 3 * 86400000));
+    expect(calculateCurrentStreak([threeDaysAgo, twoDaysAgo])).toBe(0);
+  });
+
+  it('returns correct streak count for consecutive days', () => {
+    const dates: string[] = [];
+    for (let i = 4; i >= 0; i--) {
+      dates.push(toDateStr(new Date(Date.now() - i * 86400000)));
+    }
+    expect(calculateCurrentStreak(dates)).toBe(5);
+  });
+
+  it('last contribution must be today or yesterday to have active streak', () => {
+    const threeDaysAgo = toDateStr(new Date(Date.now() - 3 * 86400000));
+    const fourDaysAgo = toDateStr(new Date(Date.now() - 4 * 86400000));
+    expect(calculateCurrentStreak([threeDaysAgo, fourDaysAgo])).toBe(0);
+  });
+
+  it('handles year boundary: Dec 31 to Jan 1 transition', () => {
+    expect(dateDiffDays('2023-12-31', '2024-01-01')).toBe(1);
+  });
+
+  it('ignores duplicate dates (same day multiple commits)', () => {
+    const today = toDateStr(new Date());
+    expect(calculateCurrentStreak([today, today, today])).toBe(1);
+  });
+
+  it('returns 0 when last run does not end today or yesterday', () => {
+    const dates = ['2024-07-01', '2024-07-02', '2024-07-03'];
+    expect(calculateCurrentStreak(dates)).toBe(0);
+  });
+});
+
+describe('dateDiffDays', () => {
+  it('returns 1 for consecutive days', () => {
+    expect(dateDiffDays('2024-07-01', '2024-07-02')).toBe(1);
+  });
+
+  it('returns -1 for reverse order', () => {
+    expect(dateDiffDays('2024-07-02', '2024-07-01')).toBe(-1);
+  });
+
+  it('returns 0 for same day', () => {
+    expect(dateDiffDays('2024-07-01', '2024-07-01')).toBe(0);
+  });
+
+  it('handles year boundary', () => {
+    expect(dateDiffDays('2023-12-31', '2024-01-01')).toBe(1);
+  });
+});
+
+describe('toDateStr', () => {
+  it('formats date as YYYY-MM-DD', () => {
+    const date = new Date('2024-07-03T12:00:00Z');
+    expect(toDateStr(date)).toBe('2024-07-03');
+  });
+
+  it('pads single-digit month and day', () => {
+    const date = new Date('2024-01-05T00:00:00Z');
+    expect(toDateStr(date)).toBe('2024-01-05');
+  });
+});

vitest.config.ts

@@ -0,0 +1,15 @@
+import { defineConfig } from "vitest/config";
+import path from "path";
+
+export default defineConfig({
+  test: {
+    include: ["test/**/*.test.ts"],
+    environment: "node",
+    globals: true,
+  },
+  resolve: {
+    alias: {
+      "@": path.resolve(__dirname, "./src"),
+    },
+  },
+});