wasmbrowsertest

Run Go wasm tests easily in your browser.

If you have a codebase targeting the wasm platform, chances are you would want to test your code in a browser. Currently, that process is a bit cumbersome:

The test needs to be compiled to a wasm file.
Then loaded into an HTML file along with the wasm_exec.js.
And finally, this needs to be served with a static file server and then loaded in the browser.

This tool automates all of that. So you just have to type GOOS=js GOARCH=wasm go test, and it automatically executes the tests inside a browser !

Quickstart

go install github.com/agnivade/wasmbrowsertest@latest. This will place the binary in $GOPATH/bin, or $GOBIN, if that has a different value.
Rename the binary to go_js_wasm_exec.
Add $GOBIN to $PATH if it is not already done.
Run tests as usual: GOOS=js GOARCH=wasm go test.
You can also take a cpu profile. Set the -cpuprofile flag for that.

Ok, but how does the magic work ?

go test allows invocation of a different binary to run a test. go help test has a line:

-exec xprog
	    Run the test binary using xprog. The behavior is the same as
	    in 'go run'. See 'go help run' for details.

And go help run says:

By default, 'go run' runs the compiled binary directly: 'a.out arguments...'.
If the -exec flag is given, 'go run' invokes the binary using xprog:
	'xprog a.out arguments...'.
If the -exec flag is not given, GOOS or GOARCH is different from the system
default, and a program named go_$GOOS_$GOARCH_exec can be found
on the current search path, 'go run' invokes the binary using that program,
for example 'go_nacl_386_exec a.out arguments...'. This allows execution of
cross-compiled programs when a simulator or other execution method is
available.

So essentially, there are 2 ways:

Either have a binary with the name of go_js_wasm_exec in your $PATH.
Or set the -exec flag in your tests.

Use whatever works for you.

How is a CPU profile taken ?

A CPU profile is run during the duration of the test, and then converted to the pprof format so that it can be natively analyzed with the Go toolchain.

Can I run something which is not a test ?

Yep. GOOS=js GOARCH=wasm go run main.go also works. If you want to actually see the application running in the browser, set the WASM_HEADLESS variable to off like so WASM_HEADLESS=off GOOS=js GOARCH=wasm go run main.go.

Can I use this inside Travis ?

Sure.

Add these lines to your .travis.yml

addons:
  chrome: stable

install:
- go install github.com/agnivade/wasmbrowsertest@latest
- mv $GOPATH/bin/wasmbrowsertest $GOPATH/bin/go_js_wasm_exec
- export PATH=$GOPATH/bin:$PATH

Now, just setting GOOS=js GOARCH=wasm will run your tests using wasmbrowsertest. For other CI environments, you have to do something similar.

Can I use this inside Github Action?

Sure.

Add these lines to your .github/workflows/ci.yml

PS: adjust the go version you need in go-version section

on: [push, pull_request]
name: Unit Test
jobs:
  test:
    strategy:
      matrix:
        go-version: [1.xx.x]
        os: [ubuntu-latest]
    runs-on: ${{ matrix.os }}
    steps:
    - name: Install Go
      uses: actions/setup-go@v2
      with:
        go-version: ${{ matrix.go-version }}
    - name: Install chrome
      uses: browser-actions/setup-chrome@latest
    - name: Install dep
      run: go install github.com/agnivade/wasmbrowsertest@latest
    - name: Setup wasmexec
      run: mv $(go env GOPATH)/bin/wasmbrowsertest $(go env GOPATH)/bin/go_js_wasm_exec
    - name: Checkout code
      uses: actions/checkout@v2

What sorts of browsers are supported ?

This tool uses the ChromeDP protocol to run the tests inside a Chrome browser. So Chrome or any blink-based browser will work.

Why not firefox ?

Great question. The initial idea was to use a Selenium API and drive any browser to run the tests. But unfortunately, geckodriver does not support the ability to capture console logs - mozilla/geckodriver#284. Hence, the shift to use the ChromeDP protocol circumvents the need to have any external driver binary and just have a browser installed in the machine.

realPy/wasmbrowsertest