For me, org.jenkins-ci.main:jenkins-test-harness:jar:2.1:test defined version 4.5 and a compile dependency was defining 4.2.x. Because compile dependencies get resolved first, 4.2.x was on the classpath and jenkins-test-harness could not find the class needed from 4.5. Solved it by excluding httpclient (and other artifacts in the org.apache.httpcomponents groupId) from the compile dependency.
Try running "mvn dependency:tree" to identify the problem location.
For me, org.jenkins-ci.main:jenkins-test-harness:jar:2.1:test defined version 4.5 and a compile dependency was defining 4.2.x. Because compile dependencies get resolved first, 4.2.x was on the classpath and jenkins-test-harness could not find the class needed from 4.5. Solved it by excluding httpclient (and other artifacts in the org.apache.httpcomponents groupId) from the compile dependency.
Try running "mvn dependency:tree" to identify the problem location.
http://jenkins-ci.361315.n4.nabble.com/InjectedTest-failures-due-to-class-not-found-td4787008.html