Build WebAssembly tests for the wasm32-wasip1 target and run them using wasmtime (#122)

[WASI](https://wasi.dev/) is now mature enough that we can build
binaries that target WebAssembly, and they will "just work" if run in a
WebAssembly runtime.

This means we can get rid of the
[increasingly-unmaintained](https://blog.rust-lang.org/inside-rust/2025/07/21/sunsetting-the-rustwasm-github-org/)
`wasm-pack` and `wasm-bindgen` machinery, and run tests the same way we
do for any other target, including doctests.

We *could* add a `.cargo/config.toml` to this repository that specifies
the rustflags and runner, but that would affect every package and cargo
command. Not sure if that's desirable.

Note that some of the doctests for `wasm32-wasip1` fail to compile,
probably due to #105:

<details>

<summary>Error messages</summary>

```
---- fearless_simd/src/macros.rs - macros::dispatch (line 34) stdout ----
error[E0599]: no variant or associated item named `Fallback` found for enum `Level` in the current scope
  --> fearless_simd/src/macros.rs:43:1
   |
12 | dispatch!(level, simd => sigmoid(simd, &[/*...*/], &mut [/*...*/]));
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ variant or associated item not found in `Level`
   |
   = note: this error originates in the macro `$crate::dispatch` which comes from the expansion of the macro `dispatch` (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0599`.
Couldn't compile the test.
---- fearless_simd/src/lib.rs - (line 23) stdout ----
error[E0599]: no variant or associated item named `Fallback` found for enum `Level` in the current scope
  --> fearless_simd/src/lib.rs:33:1
   |
13 | dispatch!(level, simd => sigmoid(simd, &[/*...*/], &mut [/*...*/]));
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ variant or associated item not found in `Level`
   |
   = note: this error originates in the macro `$crate::dispatch` which comes from the expansion of the macro `dispatch` (in Nightly builds, run with -Z macro-backtrace for more info)
```
</details>

I've `ignore`d those doctests for now.

Author: valadaptive

.github/workflows/ci.yml

@@ -241,22 +241,37 @@ jobs:
         uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{ env.RUST_STABLE_VER }}
-          targets: wasm32-unknown-unknown
+          targets: wasm32-unknown-unknown,wasm32-wasip1
 
       - name: restore cache
         uses: Swatinem/rust-cache@v2
         with:
           save-if: ${{ github.event_name != 'merge_group' }}
 
-      - name: install wasm-pack
+      - name: install cargo-nextest and wasmtime
         uses: taiki-e/install-action@v2
         with:
-          tool: wasm-pack
+          tool: cargo-nextest,wasmtime-cli
+
+      # We test using wasm32-wasip1, but want to make sure that wasm32-unknown-unknown still builds
+      - name: cargo build (wasm32-unknown-unknown)
+        run: |
+          cargo build --target wasm32-unknown-unknown \
+            --config 'target.wasm32-unknown-unknown.rustflags = "-Ctarget-feature=+simd128"'
+
+      - name: cargo nextest
+        run: |
+          cargo nextest run --workspace --locked --all-features --no-fail-fast --target wasm32-wasip1 \
+            --config 'target.wasm32-wasip1.rustflags = "-Ctarget-feature=+simd128"' \
+            --config 'target.wasm32-wasip1.runner = "wasmtime"'
+
+      - name: cargo test --doc
+        run: |
+          cargo test --doc --workspace --locked --all-features --no-fail-fast --target wasm32-wasip1 \
+            --config 'target.wasm32-wasip1.rustflags = "-Ctarget-feature=+simd128"' \
+            --config 'target.wasm32-wasip1.rustdocflags = "-Ctarget-feature=+simd128"' \
+            --config 'target.wasm32-wasip1.runner = "wasmtime"'
 
-      - name: Run fearless_simd_tests on Chrome
-        run: RUSTFLAGS=-Ctarget-feature=+simd128 wasm-pack test --headless --chrome
-        working-directory: fearless_simd_tests
-  
 
   check-msrv:
     name: cargo check (msrv)

Cargo.lock

@@ -31,7 +31,7 @@
 ///
 /// # Example
 ///
-/// ```
+/// ```rust
 /// use fearless_simd::{Level, Simd, dispatch};
 ///
 /// #[inline(always)]

fearless_simd/src/macros.rs

@@ -41,15 +41,14 @@ pub fn simd_test(_: TokenStream, item: TokenStream) -> TokenStream {
     #[cfg(not(any(target_arch = "x86", target_arch = "x86_64")))]
     let include_avx2 = false;
     // Note that we cannot feature-gate this with `target_arch`. If we run
-    // `wasm-pack test --headless --chrome`, then the `target_arch` will still be set to
+    // `cargo test --target wasm32-wasip1`, then the `target_arch` will still be set to
     // the operating system you are running on. Because of this, we instead add the `target_arch`
     // feature gate to the actual test.
     let include_wasm = !exclude_wasm(&input_fn_name.to_string());
 
     let fallback_snippet = if include_fallback {
         quote! {
             #[test]
-            #[cfg_attr(all(target_arch = "wasm32", target_feature = "simd128"), wasm_bindgen_test::wasm_bindgen_test)]
             fn #fallback_name() {
                 let fallback = fearless_simd::Fallback::new();
                 #input_fn_name(fallback);
@@ -101,7 +100,7 @@ pub fn simd_test(_: TokenStream, item: TokenStream) -> TokenStream {
     let wasm_snippet = if include_wasm {
         quote! {
             #[cfg(all(target_arch = "wasm32", target_feature = "simd128"))]
-            #[wasm_bindgen_test::wasm_bindgen_test]
+            #[test]
             fn #wasm_name() {
                 let wasm = unsafe { fearless_simd::wasm32::WasmSimd128::new_unchecked() };
                 #input_fn_name(wasm);

fearless_simd_dev_macros/src/lib.rs

@@ -20,7 +20,3 @@ workspace = true
 [dependencies]
 fearless_simd = { workspace = true, features = ["std"] }
 fearless_simd_dev_macros = { workspace = true }
-
-[target.'cfg(target_arch = "wasm32")'.dev-dependencies]
-wasm-bindgen-test = "0.3.50"
-wasm-bindgen = "0.2.100"

fearless_simd_tests/Cargo.toml

@@ -9,11 +9,23 @@ This is a development-only crate for testing `fearless_simd`.
 
 ### Testing WebAssembly +simd128
 
-Run browser tests with:
+To run the WebAssembly tests, first install a WebAssembly runtime such as [wasmtime](https://docs.wasmtime.dev/introduction.html):
 
 ```sh
-RUSTFLAGS=-Ctarget-feature=+simd128 wasm-pack test --headless --chrome
+cargo install --locked wasmtime-cli
 ```
 
-Currently these tests only enforce that WASM SIMD and the fallback scalar implementations match when
-run in the browser.
+Or [wasmi](https://github.com/wasmi-labs/wasmi):
+
+```sh
+cargo install --locked --features simd wasmi_cli
+```
+
+Run WebAssembly tests with:
+
+```sh
+cargo test --target wasm32-wasip1 \
+    --config 'target.wasm32-wasip1.rustflags = "-Ctarget-feature=+simd128"' \
+    --config 'target.wasm32-wasip1.rustdocflags = "-Ctarget-feature=+simd128"' \
+    --config 'target.wasm32-wasip1.runner = "wasmtime"' # or "wasmi_cli" if you installed that
+```

fearless_simd_tests/README.md

@@ -10,9 +10,6 @@
 use fearless_simd::*;
 use fearless_simd_dev_macros::simd_test;
 
-#[cfg(target_arch = "wasm32")]
-wasm_bindgen_test::wasm_bindgen_test_configure!(run_in_browser);
-
 mod harness;
 
 #[simd_test]