typst/tests/README.md

Tests

Directory structure

Top level directory structure:

• src: Testing code.
• suite: Input files. Mostly organized in parallel to the code. Each file can contain multiple tests, each of which is a section of Typst code following --- {name} ---.
• ref: References which the output is compared with to determine whether a test passed or failed.
• store: Store for PNG, PDF, and SVG output files produced by the tests.

Running the tests

Running all tests (including unit tests):

cargo test --workspace

Running just the integration tests (the tests in this directory):

cargo test --workspace --test tests

The repository includes the alias cargo testit to make this less verbose. In the examples below, we will use this alias.

Running all tests with the given name pattern. You can use regular expressions.

cargo testit math            # The name has "math" anywhere
cargo testit math page       # The name has "math" or "page" anywhere
cargo testit "^math" "^page" # The name begins with "math" or "page"
cargo testit "^(math|page)"  # Same as above.

Running all tests discovered under given paths:

cargo testit -p tests/suite/math/attach.typ
cargo testit -p tests/suite/model -p tests/suite/text

Running tests that begin with issue under a given path:

cargo testit "^issue" -p tests/suite/model

Running a test with the exact test name math-attach-mixed.

cargo testit --exact math-attach-mixed

You may find more options in the help message:

cargo testit --help

To make the integration tests go faster they don't generate PDFs or SVGs by default. Pass the --pdf or --svg flag to generate those. Mind that PDFs and SVGs are not tested automatically at the moment, so you should always check the output manually when making changes.

cargo testit --pdf

Writing tests

The syntax for an individual test is --- {name} {attr}* --- followed by some Typst code that should be tested. The name must be globally unique in the test suite, so that tests can be easily migrated across files. A test name can be followed by space-separated attributes. For instance, --- my-test html --- adds the html modifier to my-test, instructing the test runner to also test HTML output. The following attributes are currently defined:

• render: Tests paged output against a reference image (the default, only needs to be specified when html is also specified to enable both at the same)
• html: Tests HTML output against a reference HTML file. Disables the render default.
• large: Permits a reference image size exceeding 20 KiB. Should be used sparingly.

There are, broadly speaking, three kinds of tests:

• Tests that just ensure that the code runs successfully: Those typically make use of test or assert.eq (both are very similar, test is just shorter) to ensure certain properties hold when executing the Typst code.

• Tests that ensure the code emits particular diagnostic messages: Those have inline annotations like // Error: 2-7 thing was wrong. An annotation can start with either "Error", "Warning", or "Hint". The range designates the code span the diagnostic message refers to in the first non-comment line below. If the code span is in a line further below, you can write ranges like 3:2-3:7 to indicate the 2-7 column in the 3rd non-comment line.

• Tests that ensure certain output is produced:

  • Visual output: By default, the compiler produces paged output, renders it with the typst-render crate, and compares it against a reference image stored in the repository. The test runner automatically detects whether a test has visual output and requires a reference image in this case.

    To prevent bloat, it is important that the test images are kept as small as possible. To that effect, the test runner enforces a maximum size of 20 KiB. If you're updating a test and hit reference output size exceeds, see the section on "Updating reference images" below. If truly necessary, the size limit can be lifted by adding a large attribute after the test name, but this should be the case very rarely.

  • HTML output: When a test has the html attribute, the compiler produces HTML output and compares it against a reference file stored in the repository. By default, this enables testing of paged output, but you can test both at once by passing both render and html as attributes.

If you have the choice between writing a test using assertions or using reference images, prefer assertions. This makes the test easier to understand in isolation and prevents bloat due to images.

Updating reference images

If you created a new test or fixed a bug in an existing test, you may need to update the reference output used for comparison. For this, you can use the --update flag:

cargo testit --exact my-test-name --update

For visual tests, this will generally generate compressed reference images (to remain within the size limit).

If you use the VS Code test helper extension (see the tools folder), you can alternatively use the save button to update the reference output.