mirror of
https://github.com/swc-project/swc.git
synced 2024-11-24 18:28:13 +03:00
790a262c07
swc_babel_ast: - Rename as `swc_estree_ast`. swc_babel_compat: - Rename as `swc_estree_compat`. swc_babel_visit: - Rename as `swc_estree_visit`.
31 lines
1.4 KiB
Markdown
31 lines
1.4 KiB
Markdown
## How tests work
|
|
|
|
The babel-compat tests are mostly written as fixtures, similar to the [@babel/parser tests](https://github.com/babel/babel/tree/main/packages/babel-parser/test/fixtures). The `src/convert.rs` test runner looks in the `fixtures/` directory for input and expected output files. Input files are parsed into an SWC AST and converted to a Babel AST in Rust. Output files are parsed directly into a Babel AST. The two ASTs are then compared, with any differences causing the test to fail.
|
|
|
|
## How to write a test
|
|
|
|
**Step 1**: Create a new fixture dir and input file.
|
|
|
|
```bash
|
|
mkdir fixtures/my-test
|
|
echo "var a = true;" > fixtures/my-test/input.js
|
|
```
|
|
|
|
**Step 2**: Generate an output file with the expected Babel AST as JSON. There's a utility script available to help, but you can do this however you like.
|
|
|
|
```bash
|
|
# If using the babelgen.js utility, run `npm install` first to get @babel/parser dependency.
|
|
node babelgen.js fixtures/my-test/input.js > fixtures/my-test/output.json
|
|
```
|
|
|
|
**Step 3**: `cargo test` should now pick up your new test automatically.
|
|
|
|
> There's a small, insignificant different between the default Babel AST and the converted one causing my test to fail.
|
|
|
|
This happens a lot with `None` and `Some(false)`. You'll probably want to add a normalizer function to the Normalizer visitor in `src/normalize/mod.rs`.
|
|
|
|
## Other random utlities
|
|
|
|
- `swcgen.js`: Prints the SWC AST as JSON.
|
|
- `compare.sh`: prints the Babel and SWC ASTs side-by-side.
|