[SPARK-4123][Project Infra]: Show new dependencies added in pull requests

Starting work on this, but need to find a way to ensure that, after doing a checkout from `apache/master`, we can successfully return to the current checkout. I believe that `git rev-parse HEAD` will get me what I want, but pushing this PR up to test what the Jenkins boxes are seeing.

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

Closes #5093 from brennonyork/SPARK-4123 and squashes the following commits:

42e243e [Brennon York] moved starting test output to before pr tests, fixed indentation, changed mvn call to build/mvn
dadd941 [Brennon York] reverted assembly pom, put the regular test suite back in play
7aa1dee [Brennon York] set new dendencies into a <code> block, removed the bash debugging flag
0074566 [Brennon York] fixed minor echo issue with quotes
e229802 [Brennon York] updated to print the new dependency found
27bb9b5 [Brennon York] changed the assembly pom to test whether the pr test will pick up new deps
5375ad8 [Brennon York] git output to dev null
9bce980 [Brennon York] ensure both gate files exist
8f3c4b4 [Brennon York] updated to reflect the correct pushed in HEAD variable
2bc7b27 [Brennon York] added a pom gate check
a18db71 [Brennon York] full test of new deps script
ea170de [Brennon York] dont let mvn execute tests
f70d8cd [Brennon York] testing mvn with package
62ffd65 [Brennon York] updated dependency output message and changed compile to package given the jenkins failure output
04747e4 [Brennon York] adding simple mvn statement to see if command executes and prints compile output
87f9bea [Brennon York] added -x flag with bash to get insight into what is executing and what isnt
9e87208 [Brennon York] added set blocks to catch any non-zero exit codes and updated output
6b3042b [Brennon York] removed excess git checkout print statements
4077d46 [Brennon York] Merge remote-tracking branch 'upstream/master' into SPARK-4123
2bb5527 [Brennon York] added echo statement so jenkins logs which pr tests are running
d027f8f [Brennon York] proper piping of unnecessary stderr and stdout
6e2890d [Brennon York] updated test output newlines
d9f6f7f [Brennon York] removed echo
bad9a3a [Brennon York] added back the new deps test
e9e3ad1 [Brennon York] removed escapes for quotes
97e5cfb [Brennon York] commenting out new deps script
17379a5 [Brennon York] Merge remote-tracking branch 'upstream/master' into SPARK-4123
56f74a8 [Brennon York] updated the unop for ensuring a test is available
f2abc8c [Brennon York] removed the git checkout
6912584 [Brennon York] added this_mssg echo output
c610d42 [Brennon York] removed the error to dev/null
b98f78c [Brennon York] added the removed deps and echo output for jenkins testing
291a8fe [Brennon York] updated location of maven binary
126ce61 [Brennon York] removing new deps test to isolate why jenkins isn't posting messages
f8011d8 [Brennon York] minor updates and style changes
63a35c9 [Brennon York] updated new dependencies test
dae7ba8 [Brennon York] Capturing output directly from dependency builds
94d3547 [Brennon York] adding the new dependencies script into the test mix
2bca3c3 [Brennon York] added a git checkout 'git rev-parse HEAD' to the end of each pr test
ae83b90 [Brennon York] removed jenkins tests to grab some values from the jenkins box
4110993 [Brennon York] beginning work on pr test to add new dependencies

2 files changed, 140 insertions, 18 deletions

diff --git a/dev/run-tests-jenkins b/dev/run-tests-jenkins
index 3a937b637e..f10aa6b59e 100755
--- a/dev/run-tests-jenkins
+++ b/dev/run-tests-jenkins
@@ -55,13 +55,14 @@ TESTS_TIMEOUT="120m" # format: http://linux.die.net/man/1/timeout
 # To write a PR test:
 #+  * the file must reside within the dev/tests directory
 #+  * be an executable bash script
-#+  * accept two arguments on the command line, the first being the Github PR long commit
-#+    hash and the second the Github SHA1 hash
+#+  * accept three arguments on the command line, the first being the Github PR long commit
+#+    hash, the second the Github SHA1 hash, and the final the current PR hash
 #+  * and, lastly, return string output to be included in the pr message output that will
 #+    be posted to Github
 PR_TESTS=(
   "pr_merge_ability"
   "pr_public_classes"
+  "pr_new_dependencies"
 )
 
 function post_message () {
@@ -146,34 +147,38 @@ function send_archived_logs () {
   fi
 }
 
+# post start message
+{
+  start_message="\
+  [Test build ${BUILD_DISPLAY_NAME} has started](${BUILD_URL}consoleFull) for \
+  PR $ghprbPullId at commit [\`${SHORT_COMMIT_HASH}\`](${COMMIT_URL})."
+
+  post_message "$start_message"
+}
+
 # Environment variable to capture PR test output
 pr_message=""
+# Ensure we save off the current HEAD to revert to
+current_pr_head="`git rev-parse HEAD`"
 
 # Run pull request tests
 for t in "${PR_TESTS[@]}"; do
   this_test="${FWDIR}/dev/tests/${t}.sh"
-  # Ensure the test is a file and is executable
-  if [ -x "$this_test" ]; then
-    echo "ghprb: $ghprbActualCommit sha1: $sha1"
-    this_mssg="`bash \"${this_test}\" \"${ghprbActualCommit}\" \"${sha1}\" 2>/dev/null`"
+  # Ensure the test can be found and is a file
+  if [ -f "${this_test}" ]; then
+    echo "Running test: $t"
+    this_mssg="$(bash "${this_test}" "${ghprbActualCommit}" "${sha1}" "${current_pr_head}")"
     # Check if this is the merge test as we submit that note *before* and *after*
     # the tests run
     [ "$t" == "pr_merge_ability" ] && merge_note="${this_mssg}"
     pr_message="${pr_message}\n${this_mssg}"
+    # Ensure, after each test, that we're back on the current PR
+    git checkout -f "${current_pr_head}" &>/dev/null
+  else
+    echo "Cannot find test ${this_test}."
   fi
 done
 
-# post start message
-{
-  start_message="\
-  [Test build ${BUILD_DISPLAY_NAME} has started](${BUILD_URL}consoleFull) for \
-  PR $ghprbPullId at commit [\`${SHORT_COMMIT_HASH}\`](${COMMIT_URL})."
-
-  start_message="${start_message}\n${merge_note}"
-
-  post_message "$start_message"
-}
-
 # run tests
 {
   timeout "${TESTS_TIMEOUT}" ./dev/run-tests
@@ -222,7 +227,7 @@ done
   PR $ghprbPullId at commit [\`${SHORT_COMMIT_HASH}\`](${COMMIT_URL})."
 
   result_message="${result_message}\n${test_result_note}"
-  result_message="${result_message}\n${pr_message}"
+  result_message="${result_message}${pr_message}"
 
   post_message "$result_message"
 }
diff --git a/dev/tests/pr_new_dependencies.sh b/dev/tests/pr_new_dependencies.sh
new file mode 100755
index 0000000000..115a5cd135
--- /dev/null
+++ b/dev/tests/pr_new_dependencies.sh
@@ -0,0 +1,117 @@
+#!/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`
+# Arg3: Current PR Commit Hash
+#+ the PR hash for the current commit
+#
+
+ghprbActualCommit="$1"
+sha1="$2"
+current_pr_head="$3"
+
+MVN_BIN="build/mvn"
+CURR_CP_FILE="my-classpath.txt"
+MASTER_CP_FILE="master-classpath.txt"
+
+# First switch over to the master branch
+git checkout master &>/dev/null
+# Find and copy all pom.xml files into a *.gate file that we can check
+# against through various `git` changes
+find -name "pom.xml" -exec cp {} {}.gate \;
+# Switch back to the current PR
+git checkout "${current_pr_head}" &>/dev/null
+
+# Check if any *.pom files from the current branch are different from the master
+difference_q=""
+for p in $(find -name "pom.xml"); do
+  [[ -f "${p}" && -f "${p}.gate" ]] && \
+    difference_q="${difference_q}$(diff $p.gate $p)"
+done
+
+# If no pom files were changed we can easily say no new dependencies were added
+if [ -z "${difference_q}" ]; then
+  echo " * This patch does not change any dependencies."
+else
+  # Else we need to manually build spark to determine what, if any, dependencies
+  # were added into the Spark assembly jar
+  ${MVN_BIN} clean package dependency:build-classpath -DskipTests 2>/dev/null | \
+    sed -n -e '/Building Spark Project Assembly/,$p' | \
+    grep --context=1 -m 2 "Dependencies classpath:" | \
+    head -n 3 | \
+    tail -n 1 | \
+    tr ":" "\n" | \
+    rev | \
+    cut -d "/" -f 1 | \
+    rev | \
+    sort > ${CURR_CP_FILE}
+
+  # Checkout the master branch to compare against
+  git checkout master &>/dev/null
+
+  ${MVN_BIN} clean package dependency:build-classpath -DskipTests 2>/dev/null | \
+    sed -n -e '/Building Spark Project Assembly/,$p' | \
+    grep --context=1 -m 2 "Dependencies classpath:" | \
+    head -n 3 | \
+    tail -n 1 | \
+    tr ":" "\n" | \
+    rev | \
+    cut -d "/" -f 1 | \
+    rev | \
+    sort > ${MASTER_CP_FILE}
+
+  DIFF_RESULTS="`diff my-classpath.txt master-classpath.txt`"
+
+  if [ -z "${DIFF_RESULTS}" ]; then
+    echo " * This patch does not change any dependencies."
+  else
+    # Pretty print the new dependencies
+    added_deps=$(echo "${DIFF_RESULTS}" | grep "<" | cut -d' ' -f2 | awk '{print "   * \`"$1"\`"}')
+    removed_deps=$(echo "${DIFF_RESULTS}" | grep ">" | cut -d' ' -f2 | awk '{print "   * \`"$1"\`"}')
+    added_deps_text=" * This patch **adds the following new dependencies:**\n${added_deps}"
+    removed_deps_text=" * This patch **removes the following dependencies:**\n${removed_deps}"
+
+    # Construct the final returned message with proper 
+    return_mssg=""
+    [ -n "${added_deps}" ] && return_mssg="${added_deps_text}"
+    if [ -n "${removed_deps}" ]; then
+      if [ -n "${return_mssg}" ]; then
+        return_mssg="${return_mssg}\n${removed_deps_text}"
+      else
+        return_mssg="${removed_deps_text}"
+      fi
+    fi
+    echo "${return_mssg}"
+  fi
+  
+  # Remove the files we've left over
+  [ -f "${CURR_CP_FILE}" ] && rm -f "${CURR_CP_FILE}"
+  [ -f "${MASTER_CP_FILE}" ] && rm -f "${MASTER_CP_FILE}"
+
+  # Clean up our mess from the Maven builds just in case
+  ${MVN_BIN} clean &>/dev/null
+fi