user6118: I copied the plutus-starter template: https://github.com/input-output-hk/plutus-starter and created a file BasicPlutusTx.hs (and added it under exposed-modules in the .cabal file).
Then I started copying over all the code from the introductory tutorial: https://plutus.readthedocs.io/en/latest/plutus/tutorials/plutus-tx.html
which includes doctests. What do I need to add to the .cabal file to run these doctests?

user6044: To run doctest, you don't need to add that to your cabal file. You need to install the doctest executable, and then run cabal repl --with-ghc=doctest. See the doctest documentation.

6118: <p>I copied the plutus-starter template: <a href="https://github.com/input-output-hk/plutus-starter" rel="nofollow noreferrer">https://github.com/input-output-hk/plutus-starter</a> and created a file <code>BasicPlutusTx.hs</code> (and added it under <code>exposed-modules</code> in the <code>.cabal</code> file).</p>
<p>Then I started copying over all the code from the introductory tutorial: <a href="https://plutus.readthedocs.io/en/latest/plutus/tutorials/plutus-tx.html" rel="nofollow noreferrer">https://plutus.readthedocs.io/en/latest/plutus/tutorials/plutus-tx.html</a>
which includes doctests. What do I need to add to the <code>.cabal</code> file to run these doctests?</p>
 6044: <p>To run <code>doctest</code>, you don't need to add that to your cabal file. You need to install the <code>doctest</code> executable, and then run <code>cabal repl --with-ghc=doctest</code>. See the <a href="https://github.com/sol/doctest" rel="nofollow noreferrer">doctest documentation</a>.</p>
