# Slint tests
This documents describe the testing infrastructure of Slint
## Syntax tests
The syntax tests are testing that the compiler show the right error messages in case of error.
The syntax tests are located in `slint_compiler/tests/syntax/` and it is driven by the
[`syntax_tests.rs`](../slint_compiler/tests/syntax_tests.rs) file. More info in the comments of that file.
In summary, each .slint files have comments with `^error` like so:
```ingore
foo bar
// ^error{parse error}
```
Meaning that there must be an error on the line above at the location pointed by the caret.
Ideally, each error message must be tested like so.
The syntax test can be run alone with
```sh
cargo test --test syntax_tests
```
## Driver tests
These tests make sure that feature in .slint behave as expected.
All the .slint files in the sub directories are going to be test by the drivers with the different
language frontends.
The `.slint` code contains a comment with some block of code which is extracted by the relevant driver.
### Interpreter test
The interpreter test is the faster test to compile and run. It test the compiler and the eval feature
as run by the viewer or such. It can be run like so:
```
cargo test -p test-driver-interpreter --
```
You can add an argument to test only for particular tests.
If there is a property `test` in the last component of the file, the test will make sure this
property equal to bool.
example:
```slint
Foo := Rectangle {
// test would fail if that property was false
property <bool> test: 1 + 1 == 2;
}
```
### Rust driver
The rust driver will compile each snippet of code and put it in a `slint!` macro in its own module
In addition, if there are ```` ```rust ```` blocks in a comment, they are extracted into a `#[test]`
function in the same module. This is usefull to test the rust api.
This is all compiled in a while program, so the `SLINT_TEST_FILTER` environment variable can be
set while building to only build the test that matches the filter.
Example: to test all the layout test:
```
SLINT_TEST_FILTER=layout cargo test -p test-driver-rust
```
Instead of putting everything in a slint! macro, it is possible to tell the driver to do the
compilation in the build.rs, with the builod-time feature:
```
SLINT_TEST_FILTER=layout cargo test -p test-driver-rust --features build-time
```
### C++ driver
The C++ test driver will take each .slint and generate a .h for it. It will also generate a .cpp that
includes it, and add the ```` ```cpp ```` block in the main function.
Each program is compiled separately. And then run.
Some macro like `assert_eq` are defined to look similar to the rust equivalent.
```
cargo test -p test-driver-cpp --
```
Note that there are also C++ unit tests that can be run by CMake
### Node driver
This is used to test the NodeJS API. It takes the ```` ```js ```` blocks in comment and make .js file
with it that loads the .slint and runs node with it.
Each test is run in a different node process.
You need to build the node integration before running the tests, even if the change was on the compiler
```
cargo build -p slint-node && cargo test -p test-driver-nodejs
```
## Doctests
```
cargo test -p doctests
```
The doctests extracts the ```` ```slint ```` from the files in the docs folder and make sure that
the snippets can be build without errors