test(calendar): EF oracle vs missalemeum 2025-2026 (0 season mismatches)

temporalEF validated against Divinum Officium data. Season-mapping handles the
Whit octave (Paschaltide), the Christmas vigil (Advent), and the resumed
Epiphany Sundays (within Time after Pentecost).

1 files changed, 116 insertions, 0 deletions

diff --git a/internal/calendar/oracle_ef_test.go b/internal/calendar/oracle_ef_test.go
new file mode 100644
index 0000000..ce4badd
--- /dev/null
+++ b/internal/calendar/oracle_ef_test.go
@@ -0,0 +1,116 @@
+package calendar_test
+
+import (
+	"encoding/json"
+	"os"
+	"sort"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/lukaszkasprzak/lectio/internal/caldata"
+	"github.com/lukaszkasprzak/lectio/internal/calendar"
+)
+
+type efOracleDay struct {
+	Tempora string `json:"tempora"`
+	Title   string `json:"title"`
+	Rank    int    `json:"rank"`
+	Colour  string `json:"colour"`
+}
+
+// efSeasonFromString maps a missalemeum tempora/title phrase (for a day in the
+// given month) to lectio's EF season. Order matters. Two position-dependent
+// subtleties: the Whit-octave weekdays ("Monday after Pentecost") are still
+// Paschaltide, so only "Sunday after Pentecost" is Time after Pentecost; and the
+// resumed Sundays after Epiphany (celebrated in autumn) sit within Time after
+// Pentecost, so an "after Epiphany" phrase in the second half of the year maps
+// there, not to Time after Epiphany.
+func efSeasonFromString(s string, month int) calendar.Season {
+	s = strings.ToLower(s)
+	has := func(subs ...string) bool {
+		for _, sub := range subs {
+			if strings.Contains(s, sub) {
+				return true
+			}
+		}
+		return false
+	}
+	switch {
+	case has("vigil of christmas"): // last day of Advent
+		return calendar.Advent
+	case has("advent"):
+		return calendar.Advent
+	case has("sunday after pentecost"), has("trinity", "christ the king", "corpus christi"):
+		return calendar.TimeAfterPentecost
+	case has("after epiphany", "epiphany"):
+		if month >= 6 { // resumed Epiphany Sundays, celebrated within Time after Pentecost
+			return calendar.TimeAfterPentecost
+		}
+		return calendar.TimeAfterEpiphany
+	case has("passion", "palm", "holy week", "maundy", "good friday", "holy saturday"):
+		return calendar.Passiontide
+	case has("septuagesima", "sexagesima", "quinquagesima"):
+		return calendar.Septuagesima
+	case has("ash wednesday", "lent"):
+		return calendar.Lent
+	case has("pentecost", "ascension", "rogation", "after easter", "easter", "low sunday", "paschal", "whit"):
+		return calendar.Easter_ // incl. the Whit octave (Mon-Sat after Pentecost)
+	case has("christmas", "nativity", "circumcision", "holy name", "octave day of christ"):
+		return calendar.Christmas
+	default:
+		return "" // unknown phrase -> skip this day
+	}
+}
+
+// TestOracleEF diffs the EF engine against missalemeum (Divinum Officium data).
+// Season is asserted strictly (validates temporalEF); rank/colour are reported
+// informationally (partial 1962 sanctoral).
+func TestOracleEF(t *testing.T) {
+	raw, err := os.ReadFile("testdata/oracle-ef.json")
+	if err != nil {
+		t.Skip("EF oracle snapshot missing; run scripts/build-oracle-ef.sh")
+	}
+	var oracle map[string]efOracleDay
+	if err := json.Unmarshal(raw, &oracle); err != nil {
+		t.Fatal(err)
+	}
+	sel := calendar.DefaultSelection()
+	sel.Form = "old"
+	layers := []calendar.Layer{caldata.Tridentine()}
+
+	dates := make([]string, 0, len(oracle))
+	for d := range oracle {
+		dates = append(dates, d)
+	}
+	sort.Strings(dates)
+
+	var seasonMiss, skipped, total int
+	shown := 0
+	for _, date := range dates {
+		od := oracle[date]
+		src := od.Tempora
+		if src == "" {
+			src = od.Title
+		}
+		day, _ := time.Parse("2006-01-02", date)
+		want := efSeasonFromString(src, int(day.Month()))
+		if want == "" {
+			skipped++
+			continue
+		}
+		total++
+		got := calendar.Compute(day.UTC(), sel, layers)
+		if got.Season != want {
+			seasonMiss++
+			if shown < 25 {
+				t.Errorf("%s: EF season got %q want %q (from %q)", date, got.Season, want, src)
+				shown++
+			}
+		}
+	}
+	t.Logf("EF oracle: %d checked, %d skipped(unmapped), %d season mismatches", total, skipped, seasonMiss)
+	if seasonMiss > 0 {
+		t.Fatalf("%d/%d EF season mismatches vs missalemeum — temporalEF is wrong", seasonMiss, total)
+	}
+}