Only run presubmit tests for projects containing changes.

.kokoro/presubmit.cfg

@@ -17,6 +17,6 @@
 # Tell the trampoline which build file to use.
 env_vars: {
     key: "TRAMPOLINE_BUILD_FILE"
-    value: "github/java-docs-samples/.kokoro/tests/run_tests.sh"
+    value: "github/java-docs-samples/.kokoro/tests/diff_tests.sh"
 }
 

.kokoro/tests/diff_tests.sh

@@ -0,0 +1,73 @@
+#!/bin/bash
+# Copyright 2017 Google Inc.
+#
+# 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.
+
+set -e -o pipefail
+shopt -s globstar
+# We spin up some subprocesses. Don't kill them on hangup
+trap '' HUP
+
+# Update gcloud and check version
+gcloud components update --quiet
+echo -e "\n ********** GCLOUD INFO *********** \n"
+gcloud -v
+echo -e "\n ********** MAVEN INFO  *********** \n"
+mvn -v
+echo -e "\n ********** GRADLE INFO *********** "
+gradle -v
+
+# Setup required enviormental variables
+export GOOGLE_APPLICATION_CREDENTIALS=${KOKORO_GFILE_DIR}/service-acct.json
+export GOOGLE_CLOUD_PROJECT=java-docs-samples-testing
+source ${KOKORO_GFILE_DIR}/aws-secrets.sh
+source ${KOKORO_GFILE_DIR}/dlp_secrets.txt
+# Activate service account
+gcloud auth activate-service-account\
+    --key-file=$GOOGLE_APPLICATION_CREDENTIALS \
+    --project=$GOOGLE_CLOUD_PROJECT
+
+echo -e "\n******************** CHECKING FOR AFFECTED FOLDERS ********************"
+# Diff to find out what has changed from master
+cd github/java-docs-samples
+find ./*/ -name pom.xml -print0 | sort -z | while read -d $'\0' file
+do
+    file=$(dirname "$file")
+    echo "------------------------------------------------------------"
+    echo "- checking $file"
+    echo "------------------------------------------------------------"
+
+
+    pushd "$file" > /dev/null
+    set +e
+    git diff --quiet master.. .
+    RTN=$?
+    set -e
+
+    # Check for changes to the current folder
+    if [ "$RTN" -eq 1 ]; then
+        echo -e "\n Change detected. Running tests. \n "
+        mvn -q --batch-mode --fail-at-end clean verify \
+           -Dfile.encoding="UTF-8" \
+           -Dorg.slf4j.simpleLogger.log.org.apache.maven.cli.transfer.Slf4jMavenTransferListener=warn \
+           -Dmaven.test.redirectTestOutputToFile=true \
+           -Dbigtable.projectID="${GOOGLE_CLOUD_PROJECT}" \
+           -Dbigtable.instanceID=instance
+        echo -e " Tests complete. \n"
+    else
+        echo -e "\n NO change found. \n"
+    fi
+
+    popd > /dev/null
+
+done