Add Tomorrow generated text contract

internal/generatedtext/tomorrow.go

@@ -0,0 +1,62 @@
+package generatedtext
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"strings"
+)
+
+type Tomorrow struct {
+	Summary             string   `json:"summary"`
+	ForecastDiscussion  []string `json:"forecast_discussion"`
+	PrecipitationTiming string   `json:"precipitation_timing,omitempty"`
+	Confidence          string   `json:"confidence,omitempty"`
+}
+
+func ValidateTomorrow(data []byte) (Tomorrow, []byte, error) {
+	decoder := json.NewDecoder(bytes.NewReader(data))
+	decoder.DisallowUnknownFields()
+
+	var value Tomorrow
+	if err := decoder.Decode(&value); err != nil {
+		return Tomorrow{}, nil, fmt.Errorf("decode tomorrow generated text: %w", err)
+	}
+	var extra any
+	if err := decoder.Decode(&extra); err != nil {
+		if err != io.EOF {
+			return Tomorrow{}, nil, fmt.Errorf("decode tomorrow generated text: %w", err)
+		}
+	} else {
+		return Tomorrow{}, nil, fmt.Errorf("decode tomorrow generated text: multiple JSON values")
+	}
+
+	value.Summary = strings.TrimSpace(value.Summary)
+	value.PrecipitationTiming = strings.TrimSpace(value.PrecipitationTiming)
+	value.Confidence = strings.TrimSpace(value.Confidence)
+	value.ForecastDiscussion = trimNonEmpty(value.ForecastDiscussion)
+	if value.Summary == "" {
+		return Tomorrow{}, nil, fmt.Errorf("tomorrow generated text summary is required")
+	}
+	if len(value.ForecastDiscussion) == 0 {
+		return Tomorrow{}, nil, fmt.Errorf("tomorrow generated text forecast discussion is required")
+	}
+
+	normalized, err := json.Marshal(value)
+	if err != nil {
+		return Tomorrow{}, nil, fmt.Errorf("normalize tomorrow generated text: %w", err)
+	}
+	return value, normalized, nil
+}
+
+func trimNonEmpty(values []string) []string {
+	out := make([]string, 0, len(values))
+	for _, value := range values {
+		trimmed := strings.TrimSpace(value)
+		if trimmed != "" {
+			out = append(out, trimmed)
+		}
+	}
+	return out
+}

internal/generatedtext/tomorrow_test.go

@@ -0,0 +1,111 @@
+package generatedtext
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestValidateTomorrowNormalizesJSON(t *testing.T) {
+	value, normalized, err := ValidateTomorrow([]byte(`{
+		"summary": " Storms become more likely tomorrow. ",
+		"forecast_discussion": [
+			"  A front will keep showers in the forecast. ",
+			"",
+			"  Temperatures stay seasonable by afternoon. "
+		],
+		"precipitation_timing": " Rain is most likely before sunrise. ",
+		"confidence": " Medium "
+	}`))
+	if err != nil {
+		t.Fatalf("ValidateTomorrow() error = %v", err)
+	}
+	if value.Summary != "Storms become more likely tomorrow." {
+		t.Fatalf("Summary = %q, want trimmed summary", value.Summary)
+	}
+	if strings.Join(value.ForecastDiscussion, "|") != "A front will keep showers in the forecast.|Temperatures stay seasonable by afternoon." {
+		t.Fatalf("ForecastDiscussion = %#v, want trimmed non-empty paragraphs", value.ForecastDiscussion)
+	}
+	if value.PrecipitationTiming != "Rain is most likely before sunrise." {
+		t.Fatalf("PrecipitationTiming = %q, want trimmed precipitation timing", value.PrecipitationTiming)
+	}
+	want := `{"summary":"Storms become more likely tomorrow.","forecast_discussion":["A front will keep showers in the forecast.","Temperatures stay seasonable by afternoon."],"precipitation_timing":"Rain is most likely before sunrise.","confidence":"Medium"}`
+	if string(normalized) != want {
+		t.Fatalf("normalized = %s, want %s", normalized, want)
+	}
+}
+
+func TestValidateTomorrowOmitsEmptyOptionalFields(t *testing.T) {
+	_, normalized, err := ValidateTomorrow([]byte(`{
+		"summary": "Storms become more likely tomorrow.",
+		"forecast_discussion": ["A front will keep showers in the forecast."],
+		"precipitation_timing": "   ",
+		"confidence": "   "
+	}`))
+	if err != nil {
+		t.Fatalf("ValidateTomorrow() error = %v", err)
+	}
+	want := `{"summary":"Storms become more likely tomorrow.","forecast_discussion":["A front will keep showers in the forecast."]}`
+	if string(normalized) != want {
+		t.Fatalf("normalized = %s, want %s", normalized, want)
+	}
+}
+
+func TestValidateTomorrowRejectsInvalidInput(t *testing.T) {
+	tests := []struct {
+		name string
+		in   string
+		want string
+	}{
+		{
+			name: "malformed",
+			in:   `{`,
+			want: "decode tomorrow generated text",
+		},
+		{
+			name: "unknown field",
+			in:   `{"summary":"Storms become more likely tomorrow.","forecast_discussion":["A front will keep showers in the forecast."],"extra":"value"}`,
+			want: `unknown field "extra"`,
+		},
+		{
+			name: "missing summary",
+			in:   `{"forecast_discussion":["A front will keep showers in the forecast."]}`,
+			want: "summary is required",
+		},
+		{
+			name: "blank summary",
+			in:   `{"summary":"  ","forecast_discussion":["A front will keep showers in the forecast."]}`,
+			want: "summary is required",
+		},
+		{
+			name: "missing forecast discussion",
+			in:   `{"summary":"Storms become more likely tomorrow."}`,
+			want: "forecast discussion is required",
+		},
+		{
+			name: "blank forecast discussion",
+			in:   `{"summary":"Storms become more likely tomorrow.","forecast_discussion":["  ",""]}`,
+			want: "forecast discussion is required",
+		},
+		{
+			name: "forecast discussion wrong type",
+			in:   `{"summary":"Storms become more likely tomorrow.","forecast_discussion":"A front will keep showers in the forecast."}`,
+			want: "cannot unmarshal string",
+		},
+		{
+			name: "multiple values",
+			in:   `{"summary":"Storms become more likely tomorrow.","forecast_discussion":["A front will keep showers in the forecast."]} {}`,
+			want: "multiple JSON values",
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			_, _, err := ValidateTomorrow([]byte(test.in))
+			if err == nil {
+				t.Fatal("ValidateTomorrow() error = nil, want error")
+			}
+			if !strings.Contains(err.Error(), test.want) {
+				t.Fatalf("ValidateTomorrow() error = %v, want %q", err, test.want)
+			}
+		})
+	}
+}