fix month & year management

Author: jycouet

app/utils/download-anomalies.ts

@@ -49,14 +49,18 @@ function isDateAffected(
       return startWeek < anomaly.end.date && endWeek > anomaly.start.date
     }
     case 'monthly': {
-      const startMonth = anomaly.start.date.slice(0, 7) + '-01'
-      const endMonth = anomaly.end.date.slice(0, 7) + '-01'
-      return date >= startMonth && date <= endMonth
+      const monthStart = date
+      const monthStartDate = new Date(`${date}T00:00:00Z`)
+      const monthEndDate = new Date(monthStartDate)
+      monthEndDate.setUTCMonth(monthEndDate.getUTCMonth() + 1)
+      monthEndDate.setUTCDate(monthEndDate.getUTCDate() - 1)
+      const monthEnd = monthEndDate.toISOString().slice(0, 10)
+      return monthStart < anomaly.end.date && monthEnd > anomaly.start.date
     }
     case 'yearly': {
-      const startYear = anomaly.start.date.slice(0, 4) + '-01-01'
-      const endYear = anomaly.end.date.slice(0, 4) + '-01-01'
-      return date >= startYear && date <= endYear
+      const yearStart = date
+      const yearEnd = `${date.slice(0, 4)}-12-31`
+      return yearStart < anomaly.end.date && yearEnd > anomaly.start.date
     }
   }
 }

test/unit/app/utils/download-anomalies.spec.ts

@@ -1,6 +1,10 @@
 import { describe, expect, it } from 'vitest'
 import { applyBlocklistCorrection } from '../../../../app/utils/download-anomalies'
-import type { WeeklyDataPoint } from '../../../../app/types/chart'
+import type {
+  MonthlyDataPoint,
+  WeeklyDataPoint,
+  YearlyDataPoint,
+} from '../../../../app/types/chart'
 
 /** Helper to build a WeeklyDataPoint from a start date and value. */
 function week(weekStart: string, value: number): WeeklyDataPoint {
@@ -18,6 +22,22 @@ function week(weekStart: string, value: number): WeeklyDataPoint {
   }
 }
 
+function month(monthStr: string, value: number): MonthlyDataPoint {
+  return {
+    value,
+    month: monthStr,
+    timestamp: new Date(`${monthStr}-01T00:00:00Z`).getTime(),
+  }
+}
+
+function year(yearStr: string, value: number): YearlyDataPoint {
+  return {
+    value,
+    year: yearStr,
+    timestamp: new Date(`${yearStr}-01-01T00:00:00Z`).getTime(),
+  }
+}
+
 describe('applyBlocklistCorrection', () => {
   // Anomaly Nov 2022: start=2022-11-15, end=2022-11-30
   it('corrects weeks overlapping the anomaly', () => {
@@ -90,4 +110,74 @@ describe('applyBlocklistCorrection', () => {
     expect(result[1]!.hasAnomaly).toBe(true)
     expect(result[1]!.value).toBeLessThan(1_000_000)
   })
+
+  // Vite anomaly: start=2025-08-04, end=2025-09-08 (spans Aug-Sep)
+  it('does not over-correct a month that only touches the anomaly end boundary', () => {
+    const data = [
+      month('2025-07', 30_000_000),
+      month('2025-08', 100_000_000), // contains spike
+      month('2025-09', 100_000_000), // contains spike (Sep 1-7)
+      month('2025-10', 30_000_000), // after anomaly end — normal!
+    ]
+
+    const result = applyBlocklistCorrection({
+      data,
+      packageName: 'vite',
+      granularity: 'monthly',
+    }) as MonthlyDataPoint[]
+
+    expect(result[1]!.hasAnomaly).toBe(true)
+    expect(result[2]!.hasAnomaly).toBe(true)
+
+    // October must NOT be modified
+    expect(result[3]!.value).toBe(30_000_000)
+    expect(result[3]!.hasAnomaly).toBeUndefined()
+  })
+
+  it('does not over-correct a month that only touches the anomaly start boundary', () => {
+    const data = [
+      month('2025-07', 30_000_000), // before anomaly start — normal!
+      month('2025-08', 100_000_000), // contains spike
+      month('2025-09', 100_000_000), // contains spike
+      month('2025-10', 30_000_000),
+    ]
+
+    const result = applyBlocklistCorrection({
+      data,
+      packageName: 'vite',
+      granularity: 'monthly',
+    }) as MonthlyDataPoint[]
+
+    // July must NOT be modified
+    expect(result[0]!.value).toBe(30_000_000)
+    expect(result[0]!.hasAnomaly).toBeUndefined()
+
+    expect(result[1]!.hasAnomaly).toBe(true)
+    expect(result[2]!.hasAnomaly).toBe(true)
+  })
+
+  it('does not over-correct a year that only touches the anomaly boundary', () => {
+    const data = [
+      year('2024', 500_000_000),
+      year('2025', 2_000_000_000), // contains spike
+      year('2026', 500_000_000),
+    ]
+
+    const result = applyBlocklistCorrection({
+      data,
+      packageName: 'vite',
+      granularity: 'yearly',
+    }) as YearlyDataPoint[]
+
+    // 2024 must NOT be modified
+    expect(result[0]!.value).toBe(500_000_000)
+    expect(result[0]!.hasAnomaly).toBeUndefined()
+
+    // 2025 must be corrected
+    expect(result[1]!.hasAnomaly).toBe(true)
+
+    // 2026 must NOT be modified
+    expect(result[2]!.value).toBe(500_000_000)
+    expect(result[2]!.hasAnomaly).toBeUndefined()
+  })
 })