How do you say is there a test today in Japanese?

Romaji: "Kyou WA tesuto ga arimasu ka"

Kanji/Hiragana: 今日はテストがありますか。

Is the correct way to say "Is there a test today?".

Kyou WA (今日[きょう] は）-As for today

Tesuto (テスト）-Test

Ga (が) this is a subject marker particle

arimasu (があります）- exists (for non living things)

Ka (か） - question marker particle

Your basically saying "As for today, does a test exist?"