Transition to wasm-bindgen-test/unstable-test-coverage

CHANGELOG.md

@@ -40,6 +40,12 @@
 * `console.*()` calls in tests are now always intercepted by default. To show them use `--nocapture`. When shown they are always printed in-place instead of after test results, analogous to `cargo test`.
   [#4356](https://github.com/rustwasm/wasm-bindgen/pull/4356)
 
+* Instrumentation is now disabled on internal functions with the `msrv` crate feature instead of `cfg(wasm_bindgen_unstable_test_coverage)`.
+  [#4369](https://github.com/rustwasm/wasm-bindgen/pull/4369)
+
+* Replaced `cfg(wasm_bindgen_unstable_test_coverage)` with crate feature `unstable-test-coverage` on `wasm-bindgen-test`.
+  [#4369](https://github.com/rustwasm/wasm-bindgen/pull/4369)
+
 ### Fixed
 
 - Fixed using [JavaScript keyword](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Lexical_grammar#keywords) as identifiers not being handled correctly.
@@ -67,6 +73,9 @@
 * Internal functions are now removed instead of invalidly imported if they are unused.
   [#4366](https://github.com/rustwasm/wasm-bindgen/pull/4366)
 
+* No coverage data is emitted when the module is not instrumented even if `unstable-test-coverage` is enabled.
+  [#4369](https://github.com/rustwasm/wasm-bindgen/pull/4369)
+
 --------------------------------------------------------------------------------
 
 ## [0.2.99](https://github.com/rustwasm/wasm-bindgen/compare/0.2.98...0.2.99)

Cargo.toml

@@ -33,7 +33,7 @@ std = []
 # The current rustc version is detected at compile-time, so enabling this
 # feature for older compilers will NOT result in a compilation error. Instead,
 # any unsupported language feature will not be used.
-msrv = ["rustversion"]
+msrv = ["rustversion", "wasm-bindgen-macro/msrv"]
 
 # Whether or not the `#[wasm_bindgen]` macro is strict and generates an error on
 # all unused attributes
@@ -67,15 +67,8 @@ wasm-bindgen-futures = { path = 'crates/futures' }
 wasm-bindgen-test-crate-a = { path = 'tests/crates/a' }
 wasm-bindgen-test-crate-b = { path = 'tests/crates/b' }
 
-[lints.rust]
-unexpected_cfgs = { level = "warn", check-cfg = ['cfg(wasm_bindgen_unstable_test_coverage)'] }
-
-[lints.clippy]
-large_enum_variant = "allow"
-new_without_default = "allow"
-overly_complex_bool_expr = "allow"
-too_many_arguments = "allow"
-type_complexity = "allow"
+[lints]
+workspace = true
 
 [workspace.lints.clippy]
 large_enum_variant = "allow"
@@ -135,6 +128,7 @@ resolver = "2"
 
 [patch.crates-io]
 js-sys = { path = 'crates/js-sys' }
+minicov = { git = 'https://github.com/daxpedda/minicov', branch = 'counters' }
 wasm-bindgen = { path = '.' }
 wasm-bindgen-futures = { path = 'crates/futures' }
 web-sys = { path = 'crates/web-sys' }

crates/backend/Cargo.toml

@@ -15,6 +15,7 @@ version = "0.2.99"
 
 [features]
 extra-traits = ["syn/extra-traits"]
+msrv = []
 
 [dependencies]
 bumpalo = "3.0.0"

crates/backend/src/codegen.rs

@@ -223,6 +223,7 @@ impl ToTokens for ast::Struct {
         let free_fn = Ident::new(&shared::free_function(&name_str), Span::call_site());
         let unwrap_fn = Ident::new(&shared::unwrap_function(&name_str), Span::call_site());
         let wasm_bindgen = &self.wasm_bindgen;
+        let coverage = coverage(wasm_bindgen);
         (quote! {
             #[automatically_derived]
             impl #wasm_bindgen::__rt::marker::SupportsConstructor for #name {}
@@ -301,9 +302,9 @@ impl ToTokens for ast::Struct {
             #[cfg(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "none")))]
             #[automatically_derived]
             const _: () = {
-                #wasm_bindgen::__wbindgen_coverage! {
                 #[no_mangle]
                 #[doc(hidden)]
+                #coverage
                 // `allow_delayed` is whether it's ok to not actually free the `ptr` immediately
                 // if it's still borrowed.
                 pub unsafe extern "C" fn #free_fn(ptr: u32, allow_delayed: u32) {
@@ -320,7 +321,6 @@ impl ToTokens for ast::Struct {
                         let _ = <#name as #wasm_bindgen::convert::FromWasmAbi>::from_abi(ptr);
                     }
                 }
-                }
             };
 
             #[automatically_derived]
@@ -496,13 +496,14 @@ impl ToTokens for ast::StructField {
         }
 
         let wasm_bindgen = &self.wasm_bindgen;
+        let coverage = coverage(wasm_bindgen);
 
         (quote! {
             #[automatically_derived]
             const _: () = {
-                #wasm_bindgen::__wbindgen_coverage! {
                 #[cfg_attr(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "none")), no_mangle)]
                 #[doc(hidden)]
+                #coverage
                 pub unsafe extern "C" fn #getter(js: u32)
                     -> #wasm_bindgen::convert::WasmRet<<#ty as #wasm_bindgen::convert::IntoWasmAbi>::Abi>
                 {
@@ -517,7 +518,6 @@ impl ToTokens for ast::StructField {
                     let val = #val;
                     <#ty as IntoWasmAbi>::into_abi(val).into()
                 }
-                }
             };
         })
         .to_tokens(tokens);
@@ -543,9 +543,9 @@ impl ToTokens for ast::StructField {
             #[cfg(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "none")))]
             #[automatically_derived]
             const _: () = {
-                #wasm_bindgen::__wbindgen_coverage! {
                 #[no_mangle]
                 #[doc(hidden)]
+                #coverage
                 pub unsafe extern "C" fn #setter(
                     js: u32,
                     #(#args,)*
@@ -559,7 +559,6 @@ impl ToTokens for ast::StructField {
                     let val = <#ty as FromWasmAbi>::from_abi(val);
                     (*js).borrow_mut().#rust_name = val;
                 }
-                }
             };
         })
         .to_tokens(tokens);
@@ -584,6 +583,7 @@ impl TryToTokens for ast::Export {
 
         let name = &self.rust_name;
         let wasm_bindgen = &self.wasm_bindgen;
+        let coverage = coverage(wasm_bindgen);
         let wasm_bindgen_futures = &self.wasm_bindgen_futures;
         let receiver = match self.method_self {
             Some(ast::MethodSelf::ByValue) => {
@@ -827,12 +827,12 @@ impl TryToTokens for ast::Export {
         (quote! {
             #[automatically_derived]
             const _: () = {
-                #wasm_bindgen::__wbindgen_coverage! {
                 #(#attrs)*
                 #[cfg_attr(
                     all(target_arch = "wasm32", any(target_os = "unknown", target_os = "none")),
                     export_name = #export_name,
                 )]
+                #coverage
                 pub unsafe extern "C" fn #generated_name(#(#args),*) -> #wasm_bindgen::convert::WasmRet<#projection::Abi> {
                     const _: () = {
                         #(#checks)*
@@ -841,7 +841,6 @@ impl TryToTokens for ast::Export {
                     let #ret = #call;
                     #convert_ret
                 }
-                }
             };
         })
         .to_tokens(into);
@@ -1870,21 +1869,21 @@ impl<T: ToTokens> ToTokens for Descriptor<'_, T> {
         let inner = &self.inner;
         let attrs = &self.attrs;
         let wasm_bindgen = &self.wasm_bindgen;
+        let coverage = coverage(wasm_bindgen);
         (quote! {
             #[cfg(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "none")))]
             #[automatically_derived]
             const _: () = {
-                #wasm_bindgen::__wbindgen_coverage! {
                 #(#attrs)*
                 #[no_mangle]
                 #[doc(hidden)]
+                #coverage
                 pub extern "C" fn #name() {
                     use #wasm_bindgen::describe::*;
                     // See definition of `link_mem_intrinsics` for what this is doing
                     #wasm_bindgen::__rt::link_mem_intrinsics();
                     #inner
                 }
-                }
             };
         })
         .to_tokens(tokens);
@@ -1969,3 +1968,15 @@ fn respan(input: TokenStream, span: &dyn ToTokens) -> TokenStream {
     }
     new_tokens.into_iter().collect()
 }
+
+#[cfg(feature = "msrv")]
+fn coverage(wasm_bindgen: &syn::Path) -> TokenStream {
+    quote! {
+        #[#wasm_bindgen::__rt::rustversion::attr(since(2024-12-18), coverage(off))]
+    }
+}
+
+#[cfg(not(feature = "msrv"))]
+fn coverage(_: &syn::Path) -> TokenStream {
+    TokenStream::new()
+}

crates/macro-support/Cargo.toml

@@ -15,6 +15,7 @@ version = "0.2.99"
 
 [features]
 extra-traits = ["syn/extra-traits"]
+msrv = ["wasm-bindgen-backend/msrv"]
 strict-macro = []
 
 [dependencies]

crates/macro/Cargo.toml

@@ -17,6 +17,7 @@ version = "0.2.99"
 proc-macro = true
 
 [features]
+msrv = ["wasm-bindgen-macro-support/msrv"]
 strict-macro = ["wasm-bindgen-macro-support/strict-macro"]
 xxx_debug_only_print_generated_code = []
 

crates/macro/ui-tests/wasm-bindgen.stderr

@@ -1,11 +1,25 @@
-error[E0433]: failed to resolve: could not find `__wbindgen_coverage` in `test`
+error[E0433]: failed to resolve: could not find `__rt` in `test`
   --> ui-tests/wasm-bindgen.rs:37:1
    |
 37 | #[wasm_bindgen(wasm_bindgen = test)]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ could not find `__wbindgen_coverage` in `test`
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ could not find `__rt` in `test`
    |
    = note: this error originates in the attribute macro `wasm_bindgen` (in Nightly builds, run with -Z macro-backtrace for more info)
 
+error[E0433]: failed to resolve: could not find `convert` in `test`
+  --> ui-tests/wasm-bindgen.rs:37:1
+   |
+37 | #[wasm_bindgen(wasm_bindgen = test)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ could not find `convert` in `test`
+   |
+   = note: this error originates in the attribute macro `wasm_bindgen` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider importing one of these items
+   |
+3  + use crate::extern_test::convert;
+   |
+3  + use wasm_bindgen::convert;
+   |
+
 error[E0425]: cannot find function `future_to_promise` in module `test`
   --> ui-tests/wasm-bindgen.rs:40:1
    |

crates/test-macro/Cargo.toml

@@ -12,6 +12,9 @@ version = "0.3.49"
 [lib]
 proc-macro = true
 
+[features]
+msrv = []
+
 [dependencies]
 proc-macro2 = "1.0"
 quote = "1.0"

crates/test-macro/src/lib.rs

@@ -93,17 +93,22 @@ pub fn wasm_bindgen_test(
     let ignore_name = if ignore.is_some() { "$" } else { "" };
 
     let wasm_bindgen_path = attributes.wasm_bindgen_path;
+    #[cfg(feature = "msrv")]
+    let coverage = quote! {
+        #[#wasm_bindgen_path::__rt::wasm_bindgen::__rt::rustversion::attr(since(2024-12-18), coverage(off))]
+    };
+    #[cfg(not(feature = "msrv"))]
+    let coverage = TokenStream::new();
     tokens.extend(
         quote! {
             const _: () = {
-                #wasm_bindgen_path::__rt::wasm_bindgen::__wbindgen_coverage! {
                 #[export_name = ::core::concat!("__wbgt_", #ignore_name, ::core::module_path!(), "::", ::core::stringify!(#ident))]
                 #[cfg(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "none")))]
+                #coverage
                 extern "C" fn __wbgt_test(cx: &#wasm_bindgen_path::__rt::Context) {
                     let test_name = ::core::concat!(::core::module_path!(), "::", ::core::stringify!(#ident));
                     #test_body
                 }
-                }
             };
         },
     );

crates/test/Cargo.toml

@@ -11,6 +11,7 @@ version = "0.3.49"
 
 [features]
 default = ["std"]
+msrv = ["wasm-bindgen/msrv", "wasm-bindgen-test-macro/msrv"]
 std = ["wasm-bindgen/std", "js-sys/std", "wasm-bindgen-futures/std"]
 
 [dependencies]
@@ -20,18 +21,11 @@ wasm-bindgen = { path = '../..', version = '=0.2.99', default-features = false }
 wasm-bindgen-futures = { path = '../futures', version = '=0.4.49', default-features = false }
 wasm-bindgen-test-macro = { path = '../test-macro', version = '=0.3.49' }
 
-[target.'cfg(all(target_arch = "wasm32", wasm_bindgen_unstable_test_coverage))'.dependencies]
-minicov = "0.3"
+[target.'cfg(target_arch = "wasm32")'.dependencies]
+unstable-test-coverage = { package = "minicov", version = "0.3", optional = true }
 
-[lints.rust]
-unexpected_cfgs = { level = "warn", check-cfg = ['cfg(wasm_bindgen_unstable_test_coverage)'] }
-
-[lints.clippy]
-large_enum_variant = "allow"
-new_without_default = "allow"
-overly_complex_bool_expr = "allow"
-too_many_arguments = "allow"
-type_complexity = "allow"
+[lints]
+workspace = true
 
 [lib]
 test = false

crates/test/src/coverage.rs

@@ -1,24 +1,24 @@
 use alloc::vec::Vec;
 use wasm_bindgen::prelude::wasm_bindgen;
 
-#[cfg(wasm_bindgen_unstable_test_coverage)]
+#[cfg(feature = "unstable-test-coverage")]
 #[wasm_bindgen]
 pub fn __wbgtest_cov_dump() -> Option<Vec<u8>> {
     let mut coverage = Vec::new();
-    // SAFETY: this function is not thread-safe, but our whole test runner is running single-threaded.
-    unsafe {
-        minicov::capture_coverage(&mut coverage).unwrap();
-    }
-    if coverage.is_empty() {
-        console_error!(
-            "Empty coverage data received. Make sure you compile the tests with
-        RUSTFLAGS=\"-Cinstrument-coverage -Zno-profile-runtime --emit=llvm-ir\"",
-        );
+
+    if unstable_test_coverage::counters() > 0 {
+        // SAFETY: this function is not thread-safe, but our whole test runner is running single-threaded.
+        unsafe {
+            unstable_test_coverage::capture_coverage(&mut coverage).unwrap();
+        }
+
+        Some(coverage)
+    } else {
+        None
     }
-    Some(coverage)
 }
 
-#[cfg(not(wasm_bindgen_unstable_test_coverage))]
+#[cfg(not(feature = "unstable-test-coverage"))]
 #[wasm_bindgen]
 pub fn __wbgtest_cov_dump() -> Option<Vec<u8>> {
     None

guide/src/wasm-bindgen-test/coverage.md

@@ -9,7 +9,7 @@ You can ask the runner to generate coverage data from functions marked as `#[was
 
 ## Enabling the feature
 
-To enable this feature, you need to enable `cfg(wasm_bindgen_unstable_test_coverage)`.
+To enable this feature, you need to enable the crate feature `unstable-test-coverage` on `wasm-bindgen-test`. Additionally its recommended to use the `msrv` crate feature on `wasm-bindgen-test` as well to disable profiling on internal functions, significantly improving the accuracy of the test coverage results.
 
 ## Generating the data
 
@@ -43,7 +43,7 @@ This adapts code taken from the [Rustc book], see that for more examples and gen
 ```sh
 # Run the tests:
 # `--tests` to not run documentation tests, which is currently not supported.
-RUSTFLAGS="-Cinstrument-coverage -Zno-profiler-runtime --emit=llvm-ir --cfg=wasm_bindgen_unstable_test_coverage" \
+RUSTFLAGS="-Cinstrument-coverage -Zno-profiler-runtime --emit=llvm-ir" \
 CARGO_TARGET_WASM32_UNKNOWN_UNKNOWN_RUNNER=wasm-bindgen-test-runner \
 cargo +nightly test --tests
 # Compile to object files:
@@ -54,7 +54,7 @@ crate_name=name_of_the_tested_crate_in_snake_case
 objects=()
 IFS=$'\n'
 for file in $(
-    RUSTFLAGS="-Cinstrument-coverage -Zno-profiler-runtime --emit=llvm-ir --cfg=wasm_bindgen_unstable_test_coverage" \
+    RUSTFLAGS="-Cinstrument-coverage -Zno-profiler-runtime --emit=llvm-ir" \
     cargo +nightly test --tests --no-run --message-format=json | \
     jq -r "select(.reason == \"compiler-artifact\") | (select(.target.kind == [\"test\"]) // select(.target.name == \"$crate_name\")) | .filenames[0]"
 )