groupware: finalize JMAP events integration test, with multiple changes to the model to conform with draft-ietf-calext-jscalendarbis-10 and fields that are currently not implemented in Stalwart

pkg/structs/structs.go

@@ -224,3 +224,19 @@ func AnyItem[K comparable, V any](m map[K]V, predicate func(K, V) bool) bool {
 	}
 	return false
 }
+
+func Concat[E any](arys ...[]E) []E {
+	l := 0
+	for _, ary := range arys {
+		l += len(ary)
+	}
+	r := make([]E, l)
+
+	i := 0
+	for _, ary := range arys {
+		if ary != nil {
+			i += copy(r[i:], ary)
+		}
+	}
+	return r
+}

pkg/structs/structs_test.go

@@ -164,3 +164,10 @@ func TestAnyItem(t *testing.T) {
 	assert.False(t, AnyItem(map[string]bool{"a": true, "b": false}, never))
 	assert.False(t, AnyItem(nil, never))
 }
+
+func TestConcat(t *testing.T) {
+	assert.Equal(t, []string{"a", "b", "c", "d", "e", "f"}, Concat([]string{"a", "b"}, []string{"c"}, []string{"d", "e", "f"}))
+	assert.Equal(t, []string{"a"}, Concat([]string{"a"}))
+	assert.Equal(t, []string{"a"}, Concat([]string{}, nil, []string{"a"}))
+	assert.Equal(t, []string{}, Concat[string]())
+}