Validate precipitation probabilities and ice wording

internal/weatherdata/bundle.go

@@ -3,6 +3,7 @@ package weatherdata
 
 import (
 	"encoding/json"
+	"math"
 	"time"
 )
 
@@ -137,6 +138,12 @@ func (p ForecastPeriod) HasUsableTimeBounds() bool {
 	return !p.StartTime.IsZero() && !p.EndTime.IsZero() && p.EndTime.After(p.StartTime)
 }
 
+// HasValidPrecipitationProbability reports whether an optional probability is a finite percentage.
+func (p ForecastPeriod) HasValidPrecipitationProbability() bool {
+	value := p.ProbabilityOfPrecipitationPercent
+	return value == nil || !math.IsNaN(*value) && !math.IsInf(*value, 0) && *value >= 0 && *value <= 100
+}
+
 type AlertRun struct {
 	AsOf   *time.Time        `json:"asOf,omitempty"`
 	Alerts []json.RawMessage `json:"alerts,omitempty"`

internal/weatherdata/bundle_test.go

@@ -2,6 +2,7 @@ package weatherdata
 
 import (
 	"encoding/json"
+	"math"
 	"testing"
 	"time"
 )
@@ -93,6 +94,29 @@ func TestForecastPeriodHasUsableTimeBounds(t *testing.T) {
 	}
 }
 
+func TestForecastPeriodHasValidPrecipitationProbability(t *testing.T) {
+	for _, tt := range []struct {
+		name  string
+		value *float64
+		want  bool
+	}{
+		{name: "missing", want: true},
+		{name: "zero", value: ptrProbability(0), want: true},
+		{name: "one hundred", value: ptrProbability(100), want: true},
+		{name: "negative", value: ptrProbability(-0.1)},
+		{name: "above one hundred", value: ptrProbability(100.1)},
+		{name: "not a number", value: ptrProbability(math.NaN())},
+		{name: "infinite", value: ptrProbability(math.Inf(1))},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			period := ForecastPeriod{ProbabilityOfPrecipitationPercent: tt.value}
+			if got := period.HasValidPrecipitationProbability(); got != tt.want {
+				t.Fatalf("HasValidPrecipitationProbability() = %t, want %t", got, tt.want)
+			}
+		})
+	}
+}
+
 func mustParseBundleTime(value string) time.Time {
 	parsed, err := time.Parse(time.RFC3339, value)
 	if err != nil {
@@ -100,3 +124,7 @@ func mustParseBundleTime(value string) time.Time {
 	}
 	return parsed
 }
+
+func ptrProbability(value float64) *float64 {
+	return &value
+}