From 603ac71bb476605c0ea52f6d16eb3dfe638cd83e Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Fri, 13 Mar 2026 06:28:36 +0000
Subject: [PATCH] test: add tests for yearInReviewUtils functions

Co-authored-by: is0692vs <135803462+is0692vs@users.noreply.github.com>
---
 src/lib/__tests__/yearInReviewUtils.test.ts | 107 ++++++++++++++++++++
 1 file changed, 107 insertions(+)
 create mode 100644 src/lib/__tests__/yearInReviewUtils.test.ts

diff --git a/src/lib/__tests__/yearInReviewUtils.test.ts b/src/lib/__tests__/yearInReviewUtils.test.ts
new file mode 100644
index 0000000..7cd6f5e
--- /dev/null
+++ b/src/lib/__tests__/yearInReviewUtils.test.ts
@@ -0,0 +1,107 @@
+import { describe, it, expect } from "vitest";
+import {
+    buildHourlyHeatmapFromCommitDates,
+    getMostActiveHour,
+    getMostActiveDayFromCalendar
+} from "../yearInReviewUtils";
+
+describe("buildHourlyHeatmapFromCommitDates", () => {
+    it("returns a 7x24 heatmap of zeros for an empty array", () => {
+        const heatmap = buildHourlyHeatmapFromCommitDates([]);
+        expect(heatmap.length).toBe(7);
+        heatmap.forEach(day => {
+            expect(day.length).toBe(24);
+            day.forEach(hour => expect(hour).toBe(0));
+        });
+    });
+
+    it("ignores invalid date strings", () => {
+        const heatmap = buildHourlyHeatmapFromCommitDates(["invalid-date", "not-a-date"]);
+        heatmap.forEach(day => {
+            day.forEach(hour => expect(hour).toBe(0));
+        });
+    });
+
+    it("correctly counts commit dates into the right day and hour", () => {
+        // "2023-10-01T12:00:00Z" -> Sunday (0), 12th hour
+        // "2023-10-02T14:30:00Z" -> Monday (1), 14th hour
+        // "2023-10-02T14:45:00Z" -> Monday (1), 14th hour
+        // "2023-10-07T23:59:59Z" -> Saturday (6), 23rd hour
+        const commitDates = [
+            "2023-10-01T12:00:00Z",
+            "2023-10-02T14:30:00Z",
+            "2023-10-02T14:45:00Z",
+            "2023-10-07T23:59:59Z"
+        ];
+
+        const heatmap = buildHourlyHeatmapFromCommitDates(commitDates);
+
+        expect(heatmap[0][12]).toBe(1);
+        expect(heatmap[1][14]).toBe(2);
+        expect(heatmap[6][23]).toBe(1);
+
+        // Check that other arbitrary cells are 0
+        expect(heatmap[0][0]).toBe(0);
+        expect(heatmap[3][12]).toBe(0);
+    });
+});
+
+describe("getMostActiveHour", () => {
+    it("returns 0 for an all-zero heatmap", () => {
+        const heatmap = Array.from({ length: 7 }, () => Array.from({ length: 24 }, () => 0));
+        expect(getMostActiveHour(heatmap)).toBe(0);
+    });
+
+    it("returns the correct most active hour", () => {
+        const heatmap = Array.from({ length: 7 }, () => Array.from({ length: 24 }, () => 0));
+        heatmap[0][10] = 5; // Sunday 10am has 5
+        heatmap[1][10] = 3; // Monday 10am has 3 (Total for 10am: 8)
+
+        heatmap[2][15] = 10; // Tuesday 3pm has 10 (Total for 3pm: 10)
+
+        expect(getMostActiveHour(heatmap)).toBe(15);
+    });
+
+    it("returns the earliest hour in case of a tie", () => {
+        const heatmap = Array.from({ length: 7 }, () => Array.from({ length: 24 }, () => 0));
+        heatmap[0][5] = 10; // 5am has 10
+        heatmap[1][12] = 10; // 12pm has 10
+
+        // Since `if (total > maxCount)` is used, it should keep the first one it encounters (5am)
+        expect(getMostActiveHour(heatmap)).toBe(5);
+    });
+});
+
+describe("getMostActiveDayFromCalendar", () => {
+    it("returns 'Sunday' for an empty calendar", () => {
+        expect(getMostActiveDayFromCalendar([])).toBe("Sunday");
+    });
+
+    it("ignores entries with count <= 0", () => {
+        const calendar = [
+            { date: "2023-10-01", count: 0 }, // Sunday
+            { date: "2023-10-02", count: -5 }, // Monday
+            { date: "2023-10-03", count: 1 }   // Tuesday
+        ];
+        expect(getMostActiveDayFromCalendar(calendar)).toBe("Tuesday");
+    });
+
+    it("returns the most active day", () => {
+        const calendar = [
+            { date: "2023-10-01", count: 2 }, // Sunday
+            { date: "2023-10-02", count: 10 }, // Monday
+            { date: "2023-10-09", count: 5 }, // Another Monday (Total for Monday: 15)
+            { date: "2023-10-06", count: 14 } // Friday (Total for Friday: 14)
+        ];
+        expect(getMostActiveDayFromCalendar(calendar)).toBe("Monday");
+    });
+
+    it("returns the earliest day in the week in case of a tie", () => {
+        const calendar = [
+            { date: "2023-10-03", count: 10 }, // Tuesday
+            { date: "2023-10-05", count: 10 }  // Thursday
+        ];
+        // Since `if (totals[i] > totals[maxDay])` is used, the first max day (Tuesday) should be kept.
+        expect(getMostActiveDayFromCalendar(calendar)).toBe("Tuesday");
+    });
+});