Add script to run UMD tests

package.json

@@ -14,7 +14,7 @@
     "build": "run-p build:*:prod",
     "lint": "tslint src/*.ts test/*.ts",
     "test": "run-s clean test:commonjs",
-    "test:umd": "run-s substitute_umd_bundle run_mocha; npm run clean",
+    "test:umd": "./scripts/test_umd.sh",
     "test:coverage": "nyc npm run test --all",
     "update_contracts": "for i in ${npm_package_config_artifacts}; do copyfiles -u 4 ../contracts/build/contracts/$i.json ../0x.js/src/artifacts; done;",
     "testrpc": "testrpc -p 8545 --networkId 50 -m \"${npm_package_config_mnemonic}\"",

scripts/test_umd.sh

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+# This script runs umd tests and cleans up after them while preserving the `return_code` for CI
+# UMD tests should be only run after the commonjs build cause they reuse some of the commonjs build artefacts
+run-s substitute_umd_bundle run_mocha
+return_code=$?
+npm run clean
+exit $return_code