How to allow testing in both browser and Node.js?

[RReverser]

Summary

I have code that is only using standard JS APIs, and I want to ensure it works in both browser and Node.js environments.

If I use

wasm_bindgen_test_configure!(run_in_browser);

then running e.g. wasm-pack test --headless --chrome succeeds, but wasm-pack test --node fails with:

this test suite is only configured to run in a browser, but we're only testing node.js tests so skipping

If I comment out that wasm_bindgen_test_configure!(...) call, then instead wasm-pack test --node succeeds, but browser test command fails with:

This test suite is only configured to run in node.js, but we're only running
browser tests so skipping. If you'd like to run the tests in a browser
include this in your crate when testing:

    wasm_bindgen_test::wasm_bindgen_test_configure!(run_in_browser);

You'll likely want to put that in a `#[cfg(test)]` module or at the top of an
integration test.

Is there a way to allow either environment?

Additional Details

Looks like this behavior & flags were introduced in #1465 + rustwasm/wasm-pack#630, but I don't see a way to allow either environment.

[simlay]

I think maybe you can do this with feature flags which was recently added to wasm-pack test in rustwasm/wasm-pack/pull/851.

[Saruniks]

Adding to simlay comment:

Maybe as a somewhat of a workaround (from wasm-pack v0.10.0) could be done:

#[cfg(feature = "in_browser")]
wasm_bindgen_test_configure!(run_in_browser);

In Cargo.toml:

[features]
in_browser = []

And then

wasm-pack test --node
wasm-pack test --firefox --headless -- --features "in_browser"

[RReverser]

Sure, something like that is possible, but I don't want to add feature and recompile tests just to switch testing. wasm-pack already has switch for Node.js vs browser (--node vs others), why can't it use that info to run same test Wasm in different environments if it's environment-agnostic?

[chinedufn]

There's no way to allow both environments to run right now as far as I know, but I don't think that there's a reason that this can't be done.

Right now the test runner looks at a custom section in the wasm binary to decide whether to run it using Node or the browser

wasm-bindgen/crates/cli/src/bin/wasm-bindgen-test-runner/main.rs

Line 93 in 44d577f

let custom_section = wasm.customs.remove_raw("__wasm_bindgen_test_unstable");

wasm-bindgen/crates/test/src/lib.rs

Lines 18 to 36 in 44d577f

	/// A macro used to configured how this test is executed by the
	/// `wasm-bindgen-test-runner` harness.
	///
	/// This macro is invoked as:
	///
	/// ```ignore
	/// wasm_bindgen_test_configure!(foo bar baz);
	/// ```
	///
	/// where all of `foo`, `bar`, and `baz`, would be recognized options to this
	/// macro. The currently known options to this macro are:
	///
	/// * `run_in_browser` - requires that this test is run in a browser rather than
	/// node.js, which is the default for executing tests.
	///
	/// This macro may be invoked at most one time per test suite (an entire binary
	/// like `tests/foo.rs`, not per module)
	#[macro_export]
	macro_rules! wasm_bindgen_test_configure {

I think you could change things so that there is one custom section per target environment (node, browser, etc) then have the test runner look for each.

Then run all of the environments that are in the custom sections.

I haven't spent any time thinking about how to make that all into a good user experience and whatnot in terms of how errors are reported and whether or not tests run in parallel, etc..

But at a high level multiple target environments should be possible as far as I can tell.