sjwiesman commented on a change in pull request #8437: [FLINK-12508] Expand
Testing Documentation
URL: https://github.com/apache/flink/pull/8437#discussion_r283952634
##########
File path: docs/dev/stream/testing.md
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@@ -23,138 +23,387 @@ specific language governing permissions and limitations
under the License.
-->
-This page briefly discusses how to test a Flink application in your IDE or a
local environment.
+Testing is an integral part of every software development process. As such
Apache Flink comes with tooling to test your Apache Flink application code on
different levels of the testing pyramid.
* This will be replaced by the TOC
{:toc}
-## Unit testing
+## Testing User-Defined Functions
-Usually, one can assume that Flink produces correct results outside of a
user-defined `Function`. Therefore, it is recommended to test `Function`
classes that contain the main business logic with unit tests as much as
possible.
+Usually, one can assume that Flink produces correct results outside of a
user-defined function. Therefore, it is recommended to test these classes that
contain the main business logic with unit tests as much as possible.
-For example if one implements the following `ReduceFunction`:
+### Unit Testing Stateless, Timeless UDFs
+
+
+For example, let's take the following stateless `MapFunction`.
<div class="codetabs" markdown="1">
<div data-lang="java" markdown="1">
{% highlight java %}
-public class SumReduce implements ReduceFunction<Long> {
+public class IncrementMapFunction implements MapFunction<Long, Long> {
@Override
- public Long reduce(Long value1, Long value2) throws Exception {
- return value1 + value2;
+ public Long map(Long record) throws Exception {
+ return record +1 ;
}
}
{% endhighlight %}
</div>
<div data-lang="scala" markdown="1">
{% highlight scala %}
-class SumReduce extends ReduceFunction[Long] {
+class IncrementMapFunction extends MapFunction[Long, Long] {
- override def reduce(value1: java.lang.Long, value2: java.lang.Long):
java.lang.Long = {
- value1 + value2
+ override def map(record: java.lang.Long): java.lang.Long = {
Review comment:
Scala has its own primitive types that auto coerces to the correct java
boxed or unboxed primitive.
```suggestion
override def map(record: Long): Long = {
```
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