add tests_foo cross-realm type storage test

examples/gno.land/r/tests/interfaces.go

@@ -0,0 +1,28 @@
+package tests
+
+import (
+	"strconv"
+)
+
+type Stringer interface {
+	String() string
+}
+
+var stringers []Stringer
+
+func AddStringer(str Stringer) {
+	// NOTE: this is ridiculous, a slice that will become too long
+	// eventually.  Don't do this in production programs; use
+	// gno.land/p/avl or similar structures.
+	stringers = append(stringers, str)
+}
+
+func Render(path string) string {
+	res := ""
+	// NOTE: like the function above, this function too will eventually
+	// become too expensive to call.
+	for i, stringer := range stringers {
+		res += strconv.Itoa(i) + ": " + stringer.String() + "\n"
+	}
+	return res
+}

examples/gno.land/r/tests_foo/foo.go

@@ -0,0 +1,19 @@
+package tests_foo
+
+import (
+	"gno.land/r/tests"
+)
+
+// for testing gno.land/r/tests/interfaces.go
+
+type FooStringer struct {
+	FieldA string
+}
+
+func (fs *FooStringer) String() string {
+	return "&FooStringer{" + fs.FieldA + "}"
+}
+
+func AddFooStringer(fa string) {
+	tests.AddStringer(&FooStringer{fa})
+}