Docker will checkout PR if being run during PR CI

docker/Dockerfile

@@ -70,11 +70,20 @@ ENV sp_ROOT=/comsoftware/nceplibs
 ENV w3emc_ROOT=/comsoftware/nceplibs
 
 # Obtain CCPP SCM source code, build code, and download static data
-RUN cd /comsoftware \
-  && git clone --recursive -b main https://github.com/NCAR/ccpp-scm \
-  && mkdir /comsoftware/ccpp-scm/scm/bin
-
-RUN cd /comsoftware/ccpp-scm/scm/bin \
+RUN if [ -z "$PR_NUMBER" ]; then \
+        cd /comsoftware \
+        && git clone --recursive -b main https://github.com/NCAR/ccpp-scm; \
+    else \
+        cd /comsoftware \
+        && git clone https://github.com/NCAR/ccpp-scm \
+        && cd ccpp-scm \
+        && git checkout origin pull/${PR_NUMBER}/head:test_pr \
+        && git checkout test_pr \
+        && git submodule update --init --recursive; \
+    fi
+
+RUN mkdir /comsoftware/ccpp-scm/scm/bin \
+  && cd /comsoftware/ccpp-scm/scm/bin \
   && cmake ../src \
   && make -j