Make rebuilding work for njs. (#14940)

Author: oliverchang

projects/njs/Dockerfile

@@ -21,4 +21,4 @@ RUN hg clone http://hg.nginx.org/njs
 RUN git clone --branch pcre2-10.39 https://github.com/PhilipHazel/pcre2 pcre2
 
 WORKDIR njs
-COPY build.sh $SRC/
+COPY build.sh run_tests.sh $SRC/

projects/njs/build.sh

@@ -31,8 +31,6 @@ sed -i "s/\$libS\$libR \(-lpcre2-8$\)/\$libS\$libR -Wl,-Bstatic \1 -Wl,-Bdynamic
 popd
 
 # build project
-rm -rf build
-
 ./configure
 make njs_fuzzer
 

projects/njs/run_tests.sh

@@ -0,0 +1,19 @@
+#!/bin/bash -eu
+# Copyright 2026 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+################################################################################
+
+make unit_test
+