chroma/lexers/README.md

Chroma lexers

All lexers in Chroma should now be defined in XML unless they require custom code.

Lexer tests

The tests in this directory feed a known input testdata/<name>.actual into the parser for <name> and check that its output matches <name>.expected.

It is also possible to perform several tests on a same parser <name>, by placing know inputs *.actual into a directory testdata/<name>/.

Running the tests

Run the tests as normal:

go test ./lexers

Update existing tests

When you add a new test data file (*.actual), you need to regenerate all tests. That's how Chroma creates the *.expected test file based on the corresponding lexer.

To regenerate all tests, type in your terminal:

RECORD=true go test ./lexers

This first sets the RECORD environment variable to true. Then it runs go test on the ./lexers directory of the Chroma project.

(That environment variable tells Chroma it needs to output test data. After running go test ./lexers you can remove or reset that variable.)

Windows users

Windows users will find that the RECORD=true go test ./lexers command fails in both the standard command prompt terminal and in PowerShell.

Instead we have to perform both steps separately:

• Set the RECORD environment variable to true.
  • In the regular command prompt window, the set command sets an environment variable for the current session: set RECORD=true. See this page for more.
  • In PowerShell, you can use the $env:RECORD = 'true' command for that. See this article for more.
  • You can also make a persistent environment variable by hand in the Windows computer settings. See this article for how.
• When the environment variable is set, run go test ./lexers.

Chroma will now regenerate the test files and print its results to the console window.