DATAES-994 Add setup for mutation testing.

Original PR: #568

TESTING.adoc

@@ -0,0 +1,41 @@
+= Testing
+
+== Unit tests
+
+Unit tests in the project are run with
+
+----
+./mvnw test
+----
+
+== Integration tests
+
+Integration tests are executed when
+----
+./mvnw verify
+----
+is run. There must be _docker_ running, as the integration tests use docker to start an Elasticsearch server.
+
+Integration tests are tests that have the Junit5 Tag `@Tag("integration-test")` on the test class. Normally this should not be set explicitly, but the annotation `@SpringIntegrationTest` should be used. This not only marks the test as integration test, but integrates an automatic setup of an Elasticsearch Testcontainer and integrate this with Spring, so
+that the required Beans can be automatically injected. Check _src/test/java/org/springframework/data/elasticsearch/JUnit5SampleRestClientBasedTests.java_ as a reference setup
+
+== Mutation testing
+
+The pom includes a plugin dependency to run mutation tests using [pitest](https://pitest.org/). These tests must be explicitly configured and run, they are not included in the normal build steps. Before pitest can run, a normal `./mvnw test` must be executed. The configuration excludes integration tests, only unit tests are considered.
+
+
+pitest can be run directly from the commandline
+----
+./mvnw org.pitest:pitest-maven:mutationCoverage
+----
+This will output an html report to _target/pit-reports/YYYYMMDDHHMI_.
+
+To speed-up repeated analysis of the same codebase set the withHistory parameter to true.
+----
+./mvnw -DwithHistory org.pitest:pitest-maven:mutationCoverage
+----
+
+The classes to test are defined either in the pom.xml or can be set on the commandline:
+----
+./mvnw -DwithHistory org.pitest:pitest-maven:mutationCoverage -DtargetClasses="org.springframework.data.elasticsearch.support.*"
+----

pom.xml

@@ -366,6 +366,26 @@
 					</execution>
 				</executions>
 			</plugin>
+			<plugin>
+				<groupId>org.pitest</groupId>
+				<artifactId>pitest-maven</artifactId>
+				<version>1.5.2</version>
+				<dependencies>
+					<dependency>
+						<groupId>org.pitest</groupId>
+						<artifactId>pitest-junit5-plugin</artifactId>
+						<version>0.12</version>
+					</dependency>
+				</dependencies>
+				<configuration>
+					<excludedGroups>integration-test</excludedGroups>
+					<targetClasses>
+						<param>org.springframework.data.elasticsearch.core.geo.*</param>
+					</targetClasses>
+					<excludedMethods>toString</excludedMethods>
+				</configuration>
+			</plugin>
+
 			<plugin>
 				<groupId>org.apache.maven.plugins</groupId>
 				<artifactId>maven-assembly-plugin</artifactId>

src/test/java/org/springframework/data/elasticsearch/core/geo/GeoPointUnitTests.java

@@ -0,0 +1,51 @@
+package org.springframework.data.elasticsearch.core.geo;
+
+import static org.assertj.core.api.Assertions.*;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.data.geo.Point;
+
+/**
+ * @author P.J. Meisch (pj.meisch@sothawo.com)
+ */
+class GeoPointUnitTests {
+
+	@Test
+	@DisplayName("should create From a Point")
+	void shouldCreateFromAPoint() {
+		Point point = new Point(8, 48);
+
+		GeoPoint geoPoint = GeoPoint.fromPoint(point);
+
+		assertThat(geoPoint).isEqualTo(new GeoPoint(48, 8));
+	}
+
+	@Test
+	@DisplayName("should convert to a Point")
+	void shouldConvertToAPoint() {
+
+		GeoPoint geoPoint = new GeoPoint(48, 8);
+
+		Point point = GeoPoint.toPoint(geoPoint);
+
+		assertThat(point).isEqualTo(new Point(8, 48));
+	}
+
+	@Test
+	@DisplayName("should not be equal to a Point")
+	void shouldNotBeEqualToAPoint() {
+
+		//noinspection AssertBetweenInconvertibleTypes
+		assertThat(new GeoPoint(48, 8)).isNotEqualTo(new Point(8, 48));
+	}
+
+	@Test
+	@DisplayName("should compare lat and lon values")
+	void shouldCompareLatAndLonValues() {
+
+		GeoPoint geoPoint = new GeoPoint(48, 8);
+
+		assertThat(geoPoint).isEqualTo(new GeoPoint(48, 8));
+	}
+}