Test: Add env flag to allow skip production install (#12857)

jest.config.mjs

@@ -7,12 +7,17 @@ const isProduction = process.env.NODE_ENV === "production";
 const ENABLE_CODE_COVERAGE = Boolean(process.env.ENABLE_CODE_COVERAGE);
 const TEST_STANDALONE = Boolean(process.env.TEST_STANDALONE);
 const INSTALL_PACKAGE = Boolean(process.env.INSTALL_PACKAGE);
+// When debugging production test, this flag can skip installing package
+const SKIP_PRODUCTION_INSTALL = Boolean(process.env.SKIP_PRODUCTION_INSTALL);
 const SKIP_TESTS_WITH_NEW_SYNTAX = process.versions.node.startsWith("12.");
 
 let PRETTIER_DIR = isProduction
   ? path.join(PROJECT_ROOT, "dist")
   : PROJECT_ROOT;
-if (INSTALL_PACKAGE || (isProduction && !TEST_STANDALONE)) {
+if (
+  INSTALL_PACKAGE ||
+  (isProduction && !TEST_STANDALONE && !SKIP_PRODUCTION_INSTALL)
+) {
   PRETTIER_DIR = installPrettier(PRETTIER_DIR);
 }
 process.env.PRETTIER_DIR = PRETTIER_DIR;