From 559e9de3202d8133981a3db82429c81fc6ecbb65 Mon Sep 17 00:00:00 2001
From: "Robert (Bobby) Evans" <bobby@apache.org>
Date: Thu, 18 Jun 2020 10:38:28 -0500
Subject: [PATCH] Updated coverage docs

---
 build/coverage-report | 50 +++++++++++++++++++++++++++++++++++++++++++
 docs/dev/README.md    | 14 ++++++++++--
 2 files changed, 62 insertions(+), 2 deletions(-)
 create mode 100755 build/coverage-report

diff --git a/build/coverage-report b/build/coverage-report
new file mode 100755
index 00000000000..a8bf2653cbf
--- /dev/null
+++ b/build/coverage-report
@@ -0,0 +1,50 @@
+#!/bin/bash
+
+#
+# Copyright (c) 2020, NVIDIA CORPORATION. All rights reserved.
+#
+# 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
+JVER=${JACOCO_VERSION:-"0.8.5"}
+JDEST=${JACOCO_DEST:-"./target/jacococli.jar"}
+TMP_CLASS=${TEMP_CLASS_LOC:-"./target/jacoco_classes/"}
+HTML_LOC=${HTML_LOCATION:="./target/jacoco-report/"}
+DIST_JAR=${RAPIDS_DIST_JAR:-$(ls ./dist/target/rapids-4-spark_2.12-*.jar | grep -v test | xargs readlink -f)}
+SOURCE_DIRS=${SOURCE_DIRS:-"./sql-plugin/src/main/scala/:./sql-plugin/src/main/java/:./shuffle-plugin/src/main/scala/"}
+
+SOURCE_WITH_ARGS="--sourcefiles "$(echo $SOURCE_DIRS | sed -e 's/:/ --sourcefiles /g')
+
+# Clean up the classes so we can build the report cleanly
+rm -rf "$TMP_CLASS"
+mkdir -p "$TMP_CLASS"
+pushd "$TMP_CLASS"
+jar xf "$DIST_JAR"
+rm -rf com/nvidia/shaded/ org/openucx/
+popd
+
+if [ ! -f "$JDEST" ]; then
+  # get the jacoco jar
+  mvn dependency:get -DgroupId=org.jacoco -DartifactId=org.jacoco.cli -Dclassifier=nodeps -Dversion="$JVER" -Ddest="$JDEST"
+fi
+
+if [ "$#" != "0" ]; then
+  ARGS=$@
+else
+  ARGS=$(find . -name "jacoco.exec" -printf "%p ")
+fi
+# run the report
+java -jar "$JDEST" report --classfiles "$TMP_CLASS" --html "$HTML_LOC" $SOURCE_WITH_ARGS $ARGS
+
+echo "The report is at file://"$(readlink -f "$HTML_LOC"/index.html)
diff --git a/docs/dev/README.md b/docs/dev/README.md
index a7d01186d7a..b8ddfc80333 100644
--- a/docs/dev/README.md
+++ b/docs/dev/README.md
@@ -237,8 +237,18 @@ setting up the build for profiling and adding NVTX ranges.
 
 ## Code Coverage
 
-A code coverage report can be generated by running the follow command.
+We use [jacoco](https://www.jacoco.org/jacoco/trunk/doc/) for code coverage because it lets
+us gather code coverage for both Java and Scala.  It also lets us instrument shaded jars,
+and use tests that are written in pyspark.  We have had to jump through some hoops to make
+it work, which is partly why the tests are in the `test` and `integration_test` directories.
+
+The regular [jacoco maven plugin](https://www.jacoco.org/jacoco/trunk/doc/maven.html), however
+is not currently [able to support](https://github.com/jacoco/jacoco/issues/965) this type of
+setup. So if you want to generate a coverage report you need to do it manually.  Coverage is
+collected by default so first run the tests, and then generate the report, this should be run
+from the root project directory.  It will print out the URL of the report at the end. 
  
 ```bash
-mvn scoverage:report
+mvn clean verify
+./build/coverage-report
 ```
\ No newline at end of file