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_
- [] PerformAction _not implemented yet_

### 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 params to invokations 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`