1 files changed, 34 insertions, 0 deletions
diff --git a/internal/calendar/merge_test.go b/internal/calendar/merge_test.go
new file mode 100644
index 0000000..168c56f
--- /dev/null
+++ b/internal/calendar/merge_test.go
@@ -0,0 +1,34 @@
+package calendar
+
+import "testing"
+
+func raw(fields map[string]string) RawCelebration {
+	return RawCelebration{Fields: fields, Variants: map[string]map[string]string{}}
+}
+
+func TestMergeLayers(t *testing.T) {
+	base := Layer{ID: "universal", Cels: map[string]RawCelebration{
+		"assumption": raw(map[string]string{"rank": "solemnity", "colour": "white", "name.en": "Assumption"}),
+		"st-x":       raw(map[string]string{"rank": "optional", "date": "01-02"}),
+		"drop-me":    raw(map[string]string{"rank": "memorial", "date": "03-03"}),
+	}}
+	local := Layer{ID: "krakow", Cels: map[string]RawCelebration{
+		"st-x":    raw(map[string]string{"rank": "feast"}),                      // elevate; keep date
+		"drop-me": raw(map[string]string{"suppress": "true"}),                   // remove
+		"st-new":  raw(map[string]string{"rank": "solemnity", "date": "05-08"}), // add
+	}}
+	got := mergeLayers([]Layer{base, local})
+
+	if got["st-x"].Fields["rank"] != "feast" || got["st-x"].Fields["date"] != "01-02" {
+		t.Errorf("st-x merge = %+v", got["st-x"].Fields)
+	}
+	if _, ok := got["drop-me"]; ok {
+		t.Error("drop-me should be suppressed")
+	}
+	if got["st-new"].Fields["date"] != "05-08" {
+		t.Error("st-new should be added")
+	}
+	if got["assumption"].Fields["name.en"] != "Assumption" {
+		t.Error("untouched base entry lost")
+	}
+}