add ava-script to support old node

Author: aminya

package.json

@@ -13,7 +13,7 @@
     "postbuild": "run-s bundle",
     "bundle": "node ./scripts/rollup-script.js",
     "test": "run-s test:ava test:puppeteer:basic test:puppeteer:webpack",
-    "test:ava": "cross-env TS_NODE_FILES=true ava",
+    "test:ava": "cross-env TS_NODE_FILES=true ./scripts/ava-script.js",
     "test:puppeteer:basic": "puppet-run --plugin=mocha --bundle=./test/workers/:/workers/ --serve=./bundle/worker.js:/worker.js ./test/*.chromium*.ts",
     "test:puppeteer:webpack": "puppet-run --serve ./test/webpack/dist/app.web/0.worker.js --serve ./test/webpack/dist/app.web/1.worker.js --plugin=mocha ./test/webpack/webpack.chromium.mocha.ts",
     "posttest": "tslint --project .",

scripts/ava-script.js

@@ -0,0 +1,9 @@
+const child_process = require('child_process');
+const path = require('path')
+
+if (parseFloat(process.version.match(/^v(\d+\.\d+)/)[1]) < 10) {
+  child_process.spawnSync(`npm install ava@^2`, {stdio: 'inherit'})
+  child_process.spawnSync(`node ${path.resolve('./node_modules/ava-old/cli.js')}`, {stdio: 'inherit'})
+} else {
+  child_process.spawnSync(`node ${path.resolve('./node_modules/ava/cli.js')}`, {stdio: 'inherit'})
+}