wasmer/spectests/README.md

This directory contains tests for the core WebAssembly semantics, as described in [Semantics.md](https://github.com/WebAssembly/design/blob/master/Semantics.md) and specified by the [spec interpreter](https://github.com/WebAssembly/spec/blob/master/interpreter/spec).

This files should be a direct copy of the original [WebAssembly spec tests](https://github.com/WebAssembly/spec/tree/master/test/core).

Tests are written in the [S-Expression script format](https://github.com/WebAssembly/spec/blob/master/interpreter/README.md#s-expression-syntax) defined by the interpreter.

## Autogenerated Rust test cases

This files will serve as base for autogenerating Rust testcases
when `WASM_GENERATE_SPECTESTS=1 cargo build` is executed
([src/build_spectests.rs](https://github.com/WAFoundation/wasmer/blob/master/src/build_spectests.rs)).

The result autogenerated spectests live in the [src/spectests](https://github.com/WAFoundation/wasmer/tree/master/src/spectests)
directory.

The spectests are slightly modified from the source.
This are the current things that are skipped as they are not yet supported:

## Testcases

Currently supported command assertions:

- [x] Module _mostly implemented_ (it should support named modules `(module $Xx)`).
- [x] AssertReturn _mostly implemented_ (it should support calls to named modules `(invoke $Xx "call")`).
- [ ] AssertReturnCanonicalNan _not implemented yet_
- [ ] AssertReturnArithmeticNan _not implemented yet_
- [ ] AssertTrap _not implemented yet_
- [x] AssertInvalid _Fully implemented_ (it should not require to do validation separate from compilation)
- [x] AssertMalformed _Fully implemented_
- [ ] AssertUninstantiable _not implemented yet_
- [ ] AssertExhaustion _not implemented yet_
- [ ] Register _not implemented yet_
- [x] PerformAction _partially implemented, only function invokations for now_

### Covered spectests

This spectests are currently covered:

- address.wast ✅
- align.wast ✅
- binary.wast
- block.wast ✅
- br.wast ✅
- br_if.wast ✅
- br_table.wast ✅
- break-drop.wast ✅
- call.wast ✅
- call_indirect.wast ✅
- comments.wast
- const.wast ✅
- conversions.wast ✅
- custom.wast
- data.wast ✅
- elem.wast
- endianness.wast ✅
- exports.wast ✅
- f32.wast ✅
- f32_bitwise.wast ✅
- f32_cmp.wast ✅
- f64.wast ✅
- f64_bitwise.wast ✅
- f64_cmp.wast ✅
- fac.wast
- float_exprs.wast
- float_literals.wast ✅
- float_memory.wast
- float_misc.wast
- forward.wast
- func.wast
- func_ptrs.wast ✅
- get_local.wast ✅
- globals.wast ✅
- i32.wast ✅
- i64.wast ✅
- if.wast ✅
- imports.wast
- inline-module.wast
- int_exprs.wast
- int_literals.wast
- labels.wast ✅
- left-to-right.wast ✅
- linking.wast
- loop.wast ✅
- memory.wast ✅
- memory_grow.wast
- memory_redundancy.wast ✅
- memory_trap.wast
- names.wast ✅
- nop.wast
- return.wast ✅
- select.wast ✅
- set_local.wast ✅
- skip-stack-guard-page.wast
- stack.wast
- start.wast
- store_retval.wast
- switch.wast ✅
- tee_local.wast ✅
- token.wast
- traps.wast
- type.wast ✅
- typecheck.wast
- unreachable.wast
- unreached-invalid.wast
- unwind.wast
- utf8-custom-section-id.wast
- utf8-import-field.wast
- utf8-import-module.wast
- utf8-invalid-encoding.wast

### Specific non-supported cases

There are some cases that we decided to skip for now to fasten the time to release:

- `SKIP_NAN_BITS`: Cases like invokations with params such as: `(f32.const nan:0x200000)` are currently not well supported in tests. Files modified:
  - `conversions.wast`
- `SKIP_MEMORY_GROW`: When accessing to the context memories multiple times, the mutable access to a memory index raises an error. For this reason we decied to skip the tests (for now) until this issue is resolved. Files modified:
  - `block.wast`
  - `call_indirect.wast`
  - `call.wast`
  - `globals.wast`
  - `loop.wast`
  - `if.wast`
- `SKIP_MUTABLE_GLOBALS`: Right now the WASM parser can't validate a module with imported/exported mut globals. We decided to skip the tests until Cranelift and wasmparser can handle this (original spec proposal: https://github.com/WebAssembly/mutable-global). Files modified:
  - `globals.wast`