message: Fix struct's test_to_json
  Summary: This test previously only checked that none of the comparisons crashed, not that they were true. In fact some of them were not true.
diff: @@ -318,7 +318,7 @@ mod tests {
  #[test]
  fn test_to_json() {
  - assert::pass(
  + assert::all_true(
  r#"
  struct(key = None).to_json() == '{"key":null}'
  struct(key = True).to_json() == '{"key":true}'
  @@ -330,9 +330,9 @@ struct(key = 'value\\').to_json() == '{"key":"value\\\\"}'
  struct(key = 'value/').to_json() == '{"key":"value/"}'
  struct(key = 'value\u0008').to_json() == '{"key":"value\\b"}'
  struct(key = 'value\u000C').to_json() == '{"key":"value\\f"}'
  -struct(key = 'value\\n').to_json() == '{"key":"value\\n"}'
  -struct(key = 'value\\r').to_json() == '{"key":"value\\r"}'
  -struct(key = 'value\\t').to_json() == '{"key":"value\\t"}'
  +struct(key = 'value\n').to_json() == '{"key":"value\\n"}'
  +struct(key = 'value\r').to_json() == '{"key":"value\\r"}'
  +struct(key = 'value\t').to_json() == '{"key":"value\\t"}'
  struct(foo = 42, bar = "some").to_json() == '{"foo":42,"bar":"some"}'
  struct(foo = struct(bar = "some")).to_json() == '{"foo":{"bar":"some"}}'
  struct(foo = ["bar/", "some"]).to_json() == '{"foo":["bar/","some"]}'
  