The expected values for decimal numbers are formatted as 12.2 (which is correct, since that's what QuestDB itself expects), but the DummyHttpServer.PrintBuffer method uses a StringBuilder, which uses the current culture when appending formattable objects such as doubles.

Unfortunately, just changing the threads current culture to InvariantCulture doesn't work as there are some other tests that break in that case, notably the ∞ symbol becomes Infinity.

sv-SE is one of the locales/cultures that use , as decimal separator, if you want to reproduce.