feat(calendar): Compute — build celebrations, apply precedence + transfer, cycles

Also: deterministic pick tiebreak by slug.

1 files changed, 39 insertions, 0 deletions

diff --git a/internal/calendar/calendar_test.go b/internal/calendar/calendar_test.go
new file mode 100644
index 0000000..909f1d8
--- /dev/null
+++ b/internal/calendar/calendar_test.go
@@ -0,0 +1,39 @@
+package calendar
+
+import (
+	"testing"
+)
+
+func universalTest() Layer {
+	return Layer{ID: "universal", Type: "universal", Cels: map[string]RawCelebration{
+		"assumption": {Fields: map[string]string{
+			"date": "08-15", "rank": "solemnity", "class": "bvm", "colour": "white",
+			"name.en": "Assumption of the BVM", "reading.gospel": "Lk 1:39-56",
+		}, Variants: map[string]map[string]string{}},
+		" st-monday-optional ": {Fields: map[string]string{}, Variants: map[string]map[string]string{}},
+	}}
+}
+
+func TestComputeSolemnityBeatsFeria(t *testing.T) {
+	got := Compute(d("2025-08-15"), DefaultSelection(), []Layer{universalTest()})
+	if got.Observed.Slug != "assumption" {
+		t.Fatalf("2025-08-15 observed = %q want assumption", got.Observed.Slug)
+	}
+	if got.Colour != White || got.Observed.Rank != RankSolemnity {
+		t.Errorf("assumption colour/rank wrong: %s / %v", got.Colour, got.Observed.Rank)
+	}
+	if len(got.Observed.Masses) == 0 || got.Observed.Masses[0].Readings[0].Part != "gospel" {
+		t.Errorf("proper reading not surfaced: %+v", got.Observed.Masses)
+	}
+}
+
+func TestComputeCycles(t *testing.T) {
+	// Advent 2024 opens liturgical year 2025 → Sunday cycle C, weekday cycle I.
+	got := Compute(d("2025-01-15"), DefaultSelection(), []Layer{universalTest()})
+	if got.SundayCycle != "C" {
+		t.Errorf("2024-25 Sunday cycle = %s want C", got.SundayCycle)
+	}
+	if got.WeekdayCycle != "I" {
+		t.Errorf("2025 weekday cycle = %s want I", got.WeekdayCycle)
+	}
+}