Add 3-Day Outlook generation

internal/changes/three_day_test.go

@@ -0,0 +1,66 @@
+package changes
+
+import (
+	"testing"
+	"time"
+
+	"gitea.maximumdirect.net/eric/weatherreporter/internal/briefing"
+	"gitea.maximumdirect.net/eric/weatherreporter/internal/forecast"
+	"gitea.maximumdirect.net/eric/weatherreporter/internal/report"
+)
+
+func TestCompareThreeDayDetectsDayChanges(t *testing.T) {
+	previousTemp := 70.0
+	currentTemp := 78.0
+	previousPrecip := 20.0
+	currentPrecip := 70.0
+	previous := briefing.Package{
+		Metadata: briefing.Metadata{ReportID: report.ThreeDay},
+		ThreeDay: &briefing.ThreeDay{Days: []briefing.OutlookDay{{
+			Date:        "2026-05-29",
+			Temperature: forecast.Range{Max: &previousTemp},
+			MaxPrecipitationProbability: &forecast.TimedValue{
+				Value: previousPrecip,
+				Time:  time.Date(2026, 5, 29, 9, 0, 0, 0, time.UTC),
+			},
+		}}},
+	}
+	current := briefing.Package{
+		Metadata: briefing.Metadata{ReportID: report.ThreeDay},
+		ThreeDay: &briefing.ThreeDay{Days: []briefing.OutlookDay{{
+			Date:        "2026-05-29",
+			Temperature: forecast.Range{Max: &currentTemp},
+			MaxPrecipitationProbability: &forecast.TimedValue{
+				Value: currentPrecip,
+				Time:  time.Date(2026, 5, 29, 12, 0, 0, 0, time.UTC),
+			},
+			Dayparts: []forecast.DaypartSummary{{Indicators: forecast.Indicators{Thunder: true}}},
+		}}},
+	}
+
+	changes, err := CompareThreeDay(previous, current, Thresholds{
+		TemperatureDegrees:       5,
+		PrecipProbabilityPoints:  20,
+		PrecipTimingShiftMinutes: 120,
+	})
+	if err != nil {
+		t.Fatalf("CompareThreeDay() error = %v", err)
+	}
+
+	if len(changes) == 0 {
+		t.Fatal("changes length = 0, want detected 3-day changes")
+	}
+	var foundPrecip bool
+	var foundThunder bool
+	for _, change := range changes {
+		if change.Type == "outlook_precip_probability_change" {
+			foundPrecip = true
+		}
+		if change.Type == "outlook_thunder_risk_change" {
+			foundThunder = true
+		}
+	}
+	if !foundPrecip || !foundThunder {
+		t.Fatalf("changes = %#v, want precipitation and thunder changes", changes)
+	}
+}