Update TESTING.adoc

Removed the section about mutation testing as this dependency has never really been used and was already removed

Author: sothawo

Diff for: TESTING.adoc

@@ -18,24 +18,3 @@ is run. There must be _docker_ running, as the integration tests use docker to s
 
 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
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-== 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.
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-
-pitest can be run directly from the commandline
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-./mvnw org.pitest:pitest-maven:mutationCoverage
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-This will output an html report to _target/pit-reports/YYYYMMDDHHMI_.
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-To speed-up repeated analysis of the same codebase set the withHistory parameter to true.
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-./mvnw -DwithHistory org.pitest:pitest-maven:mutationCoverage
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-
-The classes to test are defined either in the pom.xml or can be set on the commandline:
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-./mvnw -DwithHistory org.pitest:pitest-maven:mutationCoverage -DtargetClasses="org.springframework.data.elasticsearch.support.*"
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