1 files changed, 30 insertions, 0 deletions
diff --git a/internal/calendar/refine_test.go b/internal/calendar/refine_test.go
new file mode 100644
index 0000000..1f376c4
--- /dev/null
+++ b/internal/calendar/refine_test.go
@@ -0,0 +1,30 @@
+package calendar
+
+import "testing"
+
+func TestChristmasIsSolemnity(t *testing.T) {
+	got := Compute(d("2025-12-25"), DefaultSelection(), []Layer{universalTest()})
+	if got.Season != Christmas || got.Observed.Slug != "christmas" || got.Observed.Rank != RankSolemnity {
+		t.Errorf("2025-12-25 = %s/%s/%v, want christmas/solemnity", got.Season, got.Observed.Slug, got.Observed.Rank)
+	}
+}
+
+func TestFeastOfLordReplacesSunday(t *testing.T) {
+	// A feast of the Lord (band 5) must replace an Ordinary Sunday (band 6);
+	// a saint's feast (band 7) must not. 2025-08-10 is an Ordinary Sunday.
+	layer := Layer{ID: "universal", Cels: map[string]RawCelebration{
+		"transfiguration-test": {Fields: map[string]string{"date": "08-10", "rank": "feast", "class": "lord", "name.en": "L"}, Variants: map[string]map[string]string{}},
+	}}
+	got := Compute(d("2025-08-10"), DefaultSelection(), []Layer{layer})
+	if got.Observed.Slug != "transfiguration-test" {
+		t.Errorf("feast of the Lord did not replace the Sunday: observed %q", got.Observed.Slug)
+	}
+
+	saintLayer := Layer{ID: "universal", Cels: map[string]RawCelebration{
+		"a-saint": {Fields: map[string]string{"date": "08-10", "rank": "feast", "class": "saint", "name.en": "S"}, Variants: map[string]map[string]string{}},
+	}}
+	got2 := Compute(d("2025-08-10"), DefaultSelection(), []Layer{saintLayer})
+	if got2.Observed.Layer != "temporal" {
+		t.Errorf("a saint's feast must not replace the Sunday: observed %q", got2.Observed.Slug)
+	}
+}