Build files before testing

package.json

@@ -101,7 +101,7 @@
     "test:prepare-ci": "npm-run-all --parallel --race test:registry test:build-ci",
     "test:acceptance": "npm run test:prepare-ci && wdio test/endtoend/wdio.remote.conf.js",
     "test:acceptance:local": "npm run test:build && wdio test/endtoend/wdio.local.conf.js",
-    "test:unit": "jest",
+    "test:unit": "npm run build:lib && jest",
     "test:companion": "cd ./packages/@uppy/companion && npm run test",
     "test:type": "tsc -p .",
     "test": "npm run lint && npm run test:unit && npm run test:type && npm run test:companion",