[SPARK-5313][Project Infra]: Create simple framework for highlighting changes introduced in a PR

Built a simple framework with a `dev/tests` directory to house all pull request related tests. I've moved the two original tests (`pr_merge_ability` and `pr_public_classes`) into the new `dev/tests` directory and tested to the best of my ability. At this point I need to test against Jenkins actually running the new `run-tests-jenkins` script to ensure things aren't broken down the path.

Author: Brennon York <brennon.york@capitalone.com>

Closes #5072 from brennonyork/SPARK-5313 and squashes the following commits:

8ae990c [Brennon York] added dev/run-tests back, removed echo
5db4ed4 [Brennon York] removed the git checkout
1b50050 [Brennon York] adding echos to see what jenkins is seeing
b823959 [Brennon York] removed run-tests to further test the public_classes pr test
2b9ce12 [Brennon York] added the dev/run-tests call back in
ffd49c0 [Brennon York] remove -c from bash as that was removing the trailing args
735d615 [Brennon York] removed the actual dev/run-tests command to further test jenkins
d579662 [Brennon York] Merge remote-tracking branch 'upstream/master' into SPARK-5313
aa48029 [Brennon York] removed echo lines for testing jenkins
24cd965 [Brennon York] added test output to check within jenkins to verify
3a38e73 [Brennon York] removed the temporary read
9c881ff [Brennon York] updated test suite
183b7ee [Brennon York] added documentation on how to create tests
0bc2efe [Brennon York] ensure each test starts on the current pr branch
1743378 [Brennon York] added tests in test suite
abd7430 [Brennon York] updated to include test suite

1 files changed, 39 insertions, 0 deletions

diff --git a/dev/tests/pr_merge_ability.sh b/dev/tests/pr_merge_ability.sh
new file mode 100755
index 0000000000..d9a347fe24
--- /dev/null
+++ b/dev/tests/pr_merge_ability.sh
@@ -0,0 +1,39 @@
+#!/usr/bin/env bash
+
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You 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.
+#
+
+#
+# This script follows the base format for testing pull requests against
+# another branch and returning results to be published. More details can be
+# found at dev/run-tests-jenkins.
+#
+# Arg1: The Github Pull Request Actual Commit
+#+ known as `ghprbActualCommit` in `run-tests-jenkins`
+# Arg2: The SHA1 hash
+#+ known as `sha1` in `run-tests-jenkins`
+#
+
+ghprbActualCommit="$1"
+sha1="$2"
+
+# check PR merge-ability
+if [ "${sha1}" == "${ghprbActualCommit}" ]; then
+  echo " * This patch **does not merge cleanly**."
+else
+  echo " * This patch merges cleanly."
+fi