1# Lexer tests
2
3The tests in this directory feed a known input `testdata/<name>.actual` into the parser for `<name>` and check
4that its output matches `<name>.exported`.
5
6It is also possible to perform several tests on a same parser `<name>`, by placing know inputs `*.actual` into a
7directory `testdata/<name>/`.
8
9## Running the tests
10
11Run the tests as normal:
12```go
13go test ./lexers
14```
15
16## Update existing tests
17When 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.
18
19To regenerate all tests, type in your terminal:
20
21```go
22RECORD=true go test ./lexers
23```
24
25This first sets the `RECORD` environment variable to `true`. Then it runs `go test` on the `./lexers` directory of the Chroma project.
26
27(That environment variable tells Chroma it needs to output test data. After running `go test ./lexers` you can remove or reset that variable.)
28
29### Windows users
30Windows users will find that the `RECORD=true go test ./lexers` command fails in both the standard command prompt terminal and in PowerShell.
31
32Instead we have to perform both steps separately:
33
34- Set the `RECORD` environment variable to `true`.
35 + In the regular command prompt window, the `set` command sets an environment variable for the current session: `set RECORD=true`. See [this page](https://superuser.com/questions/212150/how-to-set-env-variable-in-windows-cmd-line) for more.
36 + In PowerShell, you can use the `$env:RECORD = 'true'` command for that. See [this article](https://mcpmag.com/articles/2019/03/28/environment-variables-in-powershell.aspx) for more.
37 + You can also make a persistent environment variable by hand in the Windows computer settings. See [this article](https://www.computerhope.com/issues/ch000549.htm) for how.
38- When the environment variable is set, run `go tests ./lexers`.
39
40Chroma will now regenerate the test files and print its results to the console window.
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