Add tc39/test262 tests in k6 (#1747)

.github/workflows/tc39.yml

@@ -0,0 +1,32 @@
+name: TC39
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - master
+    tags:
+      - v*
+  pull_request:
+      paths:
+          - 'js/**'
+
+defaults:
+  run:
+    shell: bash
+
+jobs:
+  tc39:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+      - name: Install Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: 1.15.x
+      - name: Run tests
+        run: |
+          set -x
+          cd js/tc39
+          sh checkout.sh
+          go test -timeout 1h

.gitignore

@@ -2,13 +2,13 @@
 /k6.exe
 /dist
 /pkg-build
+/js/tc39/TestTC39
 
 .vscode
 *.sublime-workspace
 *.log
 *.syso
 .idea
-
 *.DS_Store
 
 /versioninfo.json

js/tc39/README.md

@@ -0,0 +1,34 @@
+# This a WIP 
+
+The point of this module is to test k6 goja+babel+core.js combo against the tc39 test suite.
+
+Ways to use it:
+1. run ./checkout.sh to checkout the last commit sha of [test262](https://github.com/tc39/test262)
+   that was tested with
+2. Run `go test &> out.log`
+
+If there are failures there will be a JSON with what failed.
+The full list of failing tests is in `breaking_test_errors.json` in order to regenerate it (in case
+of changes) it needs to become an empty JSON object `{}` and then the test should be rerun and the
+new json should be put there.
+
+TODO:
+1. ~Enable more test currently only es5 and es6 tests are enabled but babel supports some ES2016 and
+   ES2017~ 
+2. disable tests that we know won't work and .. don't care
+3. Make this faster and better 
+4. ~Move it to inside k6~
+
+
+This is obviously a modified version of [the code in the goja
+repo](https://github.com/dop251/goja/blob/master/tc39_test.go)
+
+
+# Reasons for recording breaking_test_errors.json
+
+Unfortunately k6 doesn't pass all the test that are currently defined as "interesting" and probably
+won't even more. Goja decided to just not run the ones that it knows it fails currently, but this
+means that if they stop failing, someone needs to go re-enable these tests. This also means that, if the
+previous breakage was something a user can work around in a certain way, it now might be something
+else that the user can't workaround or have another problem. For this reasons I decided that
+actually recording what breaks and checking that it doesn't change is a better idea.

js/tc39/checkout.sh

@@ -0,0 +1,9 @@
+#!/bin/sh
+sha=72154b17fc99a26e79b2586960f059360d4ce43d # this is just the commit it was last tested with
+mkdir -p ./TestTC39/test262
+cd ./TestTC39/test262
+git init
+git remote add origin https://github.com/tc39/test262.git
+git fetch origin --depth=1 "${sha}"
+git reset --hard "${sha}"
+cd -

js/tc39/tc39_norace_test.go

@@ -0,0 +1,16 @@
+// +build !race
+// Heavily influenced by the fantastic work by @dop251 for https://github.com/dop251/goja
+
+package tc39
+
+import "testing"
+
+func (ctx *tc39TestCtx) runTest(name string, f func(t *testing.T)) {
+	ctx.t.Run(name, func(t *testing.T) {
+		// t.Parallel()
+		f(t)
+	})
+}
+
+func (ctx *tc39TestCtx) flush() {
+}

js/tc39/tc39_race_test.go

@@ -0,0 +1,32 @@
+// +build race
+// Heavily influenced by the fantastic work by @dop251 for https://github.com/dop251/goja
+
+package tc39
+
+import (
+	"testing"
+)
+
+const (
+	tc39MaxTestGroupSize = 1000 // to prevent race detector complaining about too many goroutines
+)
+
+func (ctx *tc39TestCtx) runTest(name string, f func(t *testing.T)) {
+	ctx.testQueue = append(ctx.testQueue, tc39Test{name: name, f: f})
+	if len(ctx.testQueue) >= tc39MaxTestGroupSize {
+		ctx.flush()
+	}
+}
+
+func (ctx *tc39TestCtx) flush() {
+	ctx.t.Run("tc39", func(t *testing.T) {
+		for _, tc := range ctx.testQueue {
+			tc := tc
+			t.Run(tc.name, func(t *testing.T) {
+				t.Parallel()
+				tc.f(t)
+			})
+		}
+	})
+	ctx.testQueue = ctx.testQueue[:0]
+}