AGENTS.md

1### Instructions
2 
3- You can run execution tests by doing ./scripts/exec.sh to see if your changes are working.
4- If an execution test fails, you are wrong.
5- Always run execution tests after making changes.
6- You can run fixture tests by doing ./scripts/test.sh, and you can do UPDATE=1 ./scripts/test.sh to update fixtures.
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8### Minifier Semantic Assumptions
9 
10The ECMAScript minifier may rely on the documented assumptions from the SWC
11minification guide:
12 
13- Calls to primitive coercion helpers such as `toString` and `valueOf` are
14  side-effect free, and built-in object implementations have not been
15  overridden.
16- `undefined`, `NaN`, and `Infinity` have not been externally redefined.
17- `arguments.callee`, `arguments.caller`, and `Function.prototype.caller` are
18  not used.
19- Code does not depend on the exact contents of `Function.prototype.toString()`
20  or `Error.prototype.stack`.
21- Getting or setting properties on a plain object does not trigger side effects
22  through `watch`, `Proxy`, or similar mechanisms.
23- Object properties can be added, removed, and modified unless the change is
24  intentionally handling frozen, sealed, non-extensible, or descriptor-locked
25  objects.
26- `document.all` is treated as not `null`.
27- Assigning properties to classes is assumed to be side-effect free and
28  non-throwing.
29- Accessing declared top-level identifiers is assumed to be side-effect free.
30- TDZ violations are not preserved.
31- Arithmetic expressions are treated as side-effect free, including runtime
32  exceptions such as mixing `bigint` and `number`.
33 
34If a minifier change relies on an assumption beyond this list, update the
35public minification documentation or leave an explicit code comment describing
36the narrower local invariant.
37 
38### Fixture Test Addition Guide
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40- Preferred fixture roots in this crate: tests/fixture, tests/mangle, tests/pass-1, tests/pass-default, tests/full, tests/projects, benches/full.
41- Do not add new regression coverage to tests/terser. Use SWC-owned fixtures such as tests/fixture/issues instead.
42- Update generated fixture outputs with: UPDATE=1 cargo test -p swc_ecma_minifier.
43- Verify without UPDATE before finishing: cargo test -p swc_ecma_minifier.
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