v/vlib/v/tests/string_interpolation_custom_str_test.v

struct Foo {
	bar int
}

fn (f &Foo) str() string {
	return '${f.bar}'
}

struct Bar  {
	foo &Foo
}

fn test_interpolation_with_custom_ref_str() {
	foo := Foo{}
	bar := Bar { &foo }
	println(bar)
	assert '$bar'.contains('Bar{')
	assert '$bar'.contains('foo: &0')
	assert '$bar'.contains('}')
}