1 files changed, 20 insertions, 0 deletions
diff --git a/internal/calendar/computus_test.go b/internal/calendar/computus_test.go
new file mode 100644
index 0000000..c524093
--- /dev/null
+++ b/internal/calendar/computus_test.go
@@ -0,0 +1,20 @@
+package calendar
+
+import (
+	"testing"
+)
+
+func TestEasterKnownDates(t *testing.T) {
+	// Published Gregorian Easter Sundays.
+	cases := map[int]string{
+		2020: "2020-04-12", 2021: "2021-04-04", 2022: "2022-04-17",
+		2024: "2024-03-31", 2025: "2025-04-20", 2027: "2027-03-28",
+		2038: "2038-04-25", 2000: "2000-04-23",
+	}
+	for y, want := range cases {
+		got := Easter(y).Format("2006-01-02")
+		if got != want {
+			t.Errorf("Easter(%d) = %s, want %s", y, got, want)
+		}
+	}
+}